Caution: JLC's .5oz inner layer may have caused issues for me.

[Rat_Patrol]

I'm going to leave my original post, but I'm going to edit with this:
Upon thinking about responses in this thread, I'm running under the assumption that JLC's 0.5oz inner layer is highly likely to have been causing my issues. While I am not positive, other than manufacturer of the PCBs, this is the only difference between my JLC orders and orders from other vendors. PCBs from JLC had a failure rate that I did not experience with other PCB vendors that use thicker inner copper.

I would also like to issue a formal apology to JLC. While I'm not sure that the copper thickness difference was causing my issues, I'll give them the benefit of the doubt as I've not had issues with their PCBs when I order small 2 sided boards. Hey JLC: thicker inner copper layer option would be nice!

Consider this a caution about making sure your design will fully function with 0.5oz inner copper if you use JLC for your PCBs.



Original post:

Over 3 orders, I'm having up to a 50% failure rate of their PCBs.

I have a 150x200mm 4 layer board that I was running some short production runs of. Think less than 100 boards.

For some reason, which I thought was on my end for over 3 weeks, the micro would keep rebooting randomly. I could not figure it out. I replaced and re-replaced every component on that board by hand over multiple of these faulty boards to no avail. I checked everything I could think of. I've spent more time staring at the scope than I have in a long time. Last thing I figured it could be was the PCB. In these 3 orders (2 small, 1 larger order of the same gerber files), I would just set aside the non-working PCBs for later diagnosis and re-work. Well, the last 3 weeks I have spent going over these boards, trying to figure it out as they were stacking up.

The boards that worked just worked fine. I thoroughly stress test the boards before shipping, and not one has come back for warranty. So when they work, they seem to work fine.

I got some fresh PCBs in from PCBWay (same gerbers), a company which I had used for years (more expensive than JLC), and they are so far working perfectly with zero issues at all; not one failed board. I'm not sure what is intermittently wrong with those JLC boards, but I'm done wasting time and money with JLC, at least for complicated boards.

[mikeselectricstuff]

Unless you can pin to down to an actual measurable PCB fault, I think it may be premature to blame the PCB, as it could be something like a marginal component tolerance or over-sensitivity to something which could come back to bite you later.
Random reboots don't sound like much a PCB issue to me.

[Mangozac]

I'm surprised by this because I use JLC for production and I know another local company who uses them for complex 4 layer boards. Neither of us have ever had an issue with production boards.

Do you order with random test or 100% test? I choose this based on the board complexity.

[lutkeveld]

I had that too with JLC, it was related to a via annular ring that was below their tolerance.

Nevertheless, they should have caught it in either the ordering process or during quality check.

Are you sure your design complies with their tolerances?

[Rat_Patrol]

I had that too with JLC, it was related to a via annular ring that was below their tolerance.

Nevertheless, they should have caught it in either the ordering process or during quality check.

Are you sure your design complies with their tolerances?

As far as I know my design was good for their tolerances.

ETA: Though I would suspect something like the problem you pinned down.

Frankly, I'm not interested trying to "fix" the issue with JLC anymore if PCBWay can give make me boards that work.

[NivagSwerdna]

How are you generating your Gerbers?  Which EDA tool? Which version?

[Rat_Patrol]

How are you generating your Gerbers?  Which EDA tool? Which version?

Interestingly, this board is from Sprint Layout.

PCB way has no issues with the gerbers.

[48X24X48X]

I had that too with JLC, it was related to a via annular ring that was below their tolerance.

Nevertheless, they should have caught it in either the ordering process or during quality check.

Are you sure your design complies with their tolerances?

As far as I know my design was good for their tolerances.

ETA: Though I would suspect something like the problem you pinned down.

Frankly, I'm not interested trying to "fix" the issue with JLC anymore if PCBWay can give make me boards that work.

They won't fix things when there's issues. Period.
I recently have a batch of 100 pieces of production board. On the board there are JST 2.5mm through hole connectors that I have used many times in other design and were produced by them. The pins can go through the pad holes all these times as I followed JST recommended size regardless whether they are prototype or production boards made by JLC. But, to my horror after mounting all boards with the SMD parts, I found out these through hole is having a hard time getting the pins in. They argued that these are "production boards", you must adjust the hole size. I said all my previous batches of the board work out just fine with the same footprint for both prototype and production boards, why it is any different this time around? They just don't want to take any responsibility or even giving any sort of apologies. I had a $12 module mounted on every piece of the board and had to sand down the pins in order to complete the work. My bad for not checking before doing the SMD assembly. But, like the few review I have read on PCBshopper.com, "when things go right, everything is rosy with them but when things go bad, they won't even bother to take their responsibility". That sums up JLCPCB.

[thm_w]

They won't fix things when there's issues. Period.
I recently have a batch of 100 pieces of production board. On the board there are JST 2.5mm through hole connectors that I have used many times in other design and were produced by them. The pins can go through the pad holes all these times as I followed JST recommended size regardless whether they are prototype or production boards made by JLC. But, to my horror after mounting all boards with the SMD parts, I found out these through hole is having a hard time getting the pins in. They argued that these are "production boards", you must adjust the hole size. I said all my previous batches of the board work out just fine with the same footprint for both prototype and production boards, why it is any different this time around? They just don't want to take any responsibility or even giving any sort of apologies. I had a $12 module mounted on every piece of the board and had to sand down the pins in order to complete the work. My bad for not checking before doing the SMD assembly. But, like the few review I have read on PCBshopper.com, "when things go right, everything is rosy with them but when things go bad, they won't even bother to take their responsibility". That sums up JLCPCB.

What hole size, for reference?
Maybe they adjusted it down or up to meet the drills they happen to use. But I'm surprised if its that far off.

[48X24X48X]

They won't fix things when there's issues. Period.
I recently have a batch of 100 pieces of production board. On the board there are JST 2.5mm through hole connectors that I have used many times in other design and were produced by them. The pins can go through the pad holes all these times as I followed JST recommended size regardless whether they are prototype or production boards made by JLC. But, to my horror after mounting all boards with the SMD parts, I found out these through hole is having a hard time getting the pins in. They argued that these are "production boards", you must adjust the hole size. I said all my previous batches of the board work out just fine with the same footprint for both prototype and production boards, why it is any different this time around? They just don't want to take any responsibility or even giving any sort of apologies. I had a $12 module mounted on every piece of the board and had to sand down the pins in order to complete the work. My bad for not checking before doing the SMD assembly. But, like the few review I have read on PCBshopper.com, "when things go right, everything is rosy with them but when things go bad, they won't even bother to take their responsibility". That sums up JLCPCB.

What hole size, for reference?
Maybe they adjusted it down or up to meet the drills they happen to use. But I'm surprised if its that far off.

It is 0.9 mm as recommended by JST on the XH series connector (for 3 pins and above). It just doesn't line up with all the bullshit they gave because I had production runs with them using the same exact footprint.

[wraper]

It is 0.9 mm as recommended by JST on the XH series connector (for 3 pins and above). It just doesn't line up with all the bullshit they gave because I had production runs with them using the same exact footprint.

But did you measure actual diameter?
EDIT: datasheet shows 0.9mm +0.1/- 0. So tolerance does not allow to go below 0.9mm which certainly can and most likely will happen due to tolerances. You should expect there will be 0.9mm drill and plating thickness, so by default you should expect something like 0.86mm for 1oz copper, and that is already out of spec. So regardless of how badly they made PCB, it's your fault as well.

[48X24X48X]

But they need to have consistency as well. It worked well for many batches of boards before that. All made by them. That needs explanation but they kept quiet and not referring at all to those orders when queried despite me giving them all the order numbers. This is for me, the "art of Tai Chi" by irresponsible manufacturer. I have had boards redo by PCBCart, JSDPCB whenever there's a mistake.

[wraper]

But they need to have consistency as well. It worked well for many batches of boards before that. All made by them. That needs explanation but they kept quiet and not referring at all to those orders when queried despite me giving them all the order numbers. This is for me, the "art of Tai Chi" by irresponsible manufacturer. I have had boards redo by PCBCart, JSDPCB whenever there's a mistake.

There is a such thing as tolerances. If you made a marginal design, don't blame the manufacturer when you received a batch unsuitable for you but within provided manufacturer tolerances. Even if previous batches were fine. I guess your complaint was like: "it was fine before, so it must be your fault", so they told you to sod off. While proper complaint should be: "hole diameter is 0.8mm, which it's out of spec of your published +/-0.xx mm tolerance".

[Mangozac]

EDIT: datasheet shows 0.9mm +0.1/- 0. So tolerance does not allow to go below 0.9mm which certainly can and most likely will happen due to tolerances. You should expect there will be 0.9mm drill and plating thickness, so by default you should expect something like 0.86mm for 1oz copper, and that is already out of spec.

Plated through hole size is the finished hole, so after plating. Still, there is no tolerance allowed for so does have the potential to be an issue.

[wraper]

Hole size Tolerance (Plated)   +0.13mm/-0.08mm   e.g. for the 1.00mm Plated hole, the finished hole size between 0.92mm to 1.13mm is acceptable.

https://jlcpcb.com/capabilities/Capabilities

[48X24X48X]

But their explanation was: "for production batch we don't do adjustment/compensation, for prototypes, we will do adjustment". So, they do play around with the holes diameter. My guess is as a large panel consist of probably other designs, they probably want to save some drills sizes and rounded mine. I will be more careful on the holes sizes after this with all PCB manufacturer.

[wraper]

EDIT: datasheet shows 0.9mm +0.1/- 0. So tolerance does not allow to go below 0.9mm which certainly can and most likely will happen due to tolerances. You should expect there will be 0.9mm drill and plating thickness, so by default you should expect something like 0.86mm for 1oz copper, and that is already out of spec.

Plated through hole size is the finished hole, so after plating. Still, there is no tolerance allowed for so does have the potential to be an issue.

But you should consider they likely have drills with something like 0.05 mm or even 0.1mm step. So expecting they will use 0.93mm drill for 0.9mm plated hole is quite optimistic.

[Mangozac]

But you should consider they likely have drills with something like 0.05 mm or even 0.1mm step. So expecting they will use 0.93mm drill for 0.9mm plated hole is quite optimistic.

Yes that's right - as you said he hasn't allowed for any hole size tolerance. I was just pointing out that you don't have to make further allowances for the plating, as this is included in their drill size selection tolerance.

[phil from seattle]

It is 0.9 mm as recommended by JST on the XH series connector (for 3 pins and above). It just doesn't line up with all the bullshit they gave because I had production runs with them using the same exact footprint.

But did you measure actual diameter?
EDIT: datasheet shows 0.9mm +0.1/- 0. So tolerance does not allow to go below 0.9mm which certainly can and most likely will happen due to tolerances. You should expect there will be 0.9mm drill and plating thickness, so by default you should expect something like 0.86mm for 1oz copper, and that is already out of spec. So regardless of how badly they made PCB, it's your fault as well.

My experinces with JLCPBC showed that they have a pretty heavy hand with through hole plating. I generally oversize my through holes by 10-15% just to be sure.  Other manufacturers are a little more sparing on TH plating. I'm not going to defend them but they are relatively predictable for me.  I can live with their shortcomings.

[jmelson]

Over 3 orders, I'm having up to a 50% failure rate of their PCBs.

First thing, before stuffing the board, put it under a microscope or strong magnifier, and look for the probe marks on the pads.  The flying probe tester leaves a TINY dimple in the center of each pad when it tests the board.  If you don't see probe marks, the board was NOT TESTED!  Yes they can have some horribly bored girl looking for obvious shorts and opens, but a bored human will certainly miss a few.  Flying probe testers are not perfect, but they reduce failures to the PPM level.

I have had excellent luck with PCBway, well it isn't actually luck, they do the testing.

Jon

[Mangozac]

First thing, before stuffing the board, put it under a microscope or strong magnifier, and look for the probe marks on the pads.  The flying probe tester leaves a TINY dimple in the center of each pad when it tests the board.  If you don't see probe marks, the board was NOT TESTED!

As I said above though, you have to pay extra for it (as an option) if you want 100% test. Otherwise they will just do random test of a few panels in the batch.

[JLCPCB Official]

Over 3 orders, I'm having up to a 50% failure rate of their PCBs.

I have a 150x200mm 4 layer board that I was running some short production runs of. Think less than 100 boards.

For some reason, which I thought was on my end for over 3 weeks, the micro would keep rebooting randomly. I could not figure it out. I replaced and re-replaced every component on that board by hand over multiple of these faulty boards to no avail. I checked everything I could think of. I've spent more time staring at the scope than I have in a long time. Last thing I figured it could be was the PCB. In these 3 orders (2 small, 1 larger order of the same gerber files), I would just set aside the non-working PCBs for later diagnosis and re-work. Well, the last 3 weeks I have spent going over these boards, trying to figure it out as they were stacking up.

The boards that worked just worked fine. I thoroughly stress test the boards before shipping, and not one has come back for warranty. So when they work, they seem to work fine.

I got some fresh PCBs in from PCBWay (same gerbers), a company which I had used for years (more expensive than JLC), and they are so far working perfectly with zero issues at all; not one failed board. I'm not sure what is intermittently wrong with those JLC boards, but I'm done wasting time and money with JLC, at least for complicated boards.

Dear sir, could you provide your order number to me. There must be some misunderstanding. JLCPCB is the biggest PCB prototype company. We are confident of quality control.

The fact:
-By 2020, we have 6 factories, all the production line with advanced equipment;
-File Review Before Production
-Multiple testing before shipping
-Strict management of factory staff and  office staff
-High-quality raw material
....
in those ways, JLCPCB can make the quality complaint rate to be 0.25%(In the 20,000 orders, there is less than 50 orders with quality complaints). We want to know the specific reason for your order problem, we promise if we make a mistake, you will be definitely compensated. Similarly, we hope to get a fair and open evaluation.

Please provide me your order number, or leave your contact, we will find out the real situation as soon as possible. This is what a responsible PCB company needs to do.

Thanks for all the attention.

[Mecanix]

This is what a responsible PCB company needs to do.

Thanks for all the attention.

Agree. Tell'm, JLC!
Disclaimer: I've ordered hundreds of pcbs from your fab house, 2L & 4L in al colors and shapes and none (literally none) came in bad. Always within tol.

[Ice-Tea]

Seems to me you're blaming (and shaming) JLC without any actual evidence.

In addition, you seem to discard the possibility there might be a problem in your gerbers or design based on the assumption JLC is to blame. That's a dangerous approach. I personally would not be shipping products unless I knew *exactly* what the issue was. If JLC didn't flag a problem with your design, perhaps you should run it through some other vendors online verification to see if they catch anything. Or double check your design rules and DRC.

Just moving on is asking for trouble IMHO.

[mikeselectricstuff]

Seems to me you're blaming (and shaming) JLC without any actual evidence.
 I personally would not be shipping products unless I knew *exactly* what the issue was.

This, x1000

[EEVblog]

Unless you can pin to down to an actual measurable PCB fault, I think it may be premature to blame the PCB, as it could be something like a marginal component tolerance or over-sensitivity to something which could come back to bite you later.
Random reboots don't sound like much a PCB issue to me.

Yep.
It would have to be something really exotic like a thermal issue causing a problem with a marginal hairline via or track connection or something.
You can safely bet money it's not the PCB at fault.
What are your design rules?

[mikeselectricstuff]

For a problem like random reboots, my bet would be something like marginal capacitance on a crystal oscillator or similarly sensitive node, maybe coupled with excessive track length which is slightly affected by variations between PCBs - e.g. lamination differences affecting capacitance.
Could even be something as basic as a floating input pin.

[thinkfat]

I can easily imagine a crystal oscillator with the external load caps just on the edge. On some boards, with some capacitors, it will oscillate stably, on others only sometimes. Stuff like that will drive you crazy, especially since it's hard to observe.

[Siwastaja]

Oh, again this, "I don't know what I'm doing but need a scapegoat quickly to get out of the trouble I'm in, so let's blame the most improbable factor just 'cause I feel like doing that, with absolutely no proof, not even circumstantial".

Similar to blaming compiler for weird, hard-to-find bugs by default. There are people who do that.

Get the grip and continue investigating. Need more hours staring at scope. Such is this business. That's why we are paid for it.

You need to actually reproduce a scope trace showing difference in signal levels in the supposedly same net to prove this. Solder the "probe" wires to the tracks directly to eliminate bad measurement connections. Also solder to tracks (scrape off some soldermask), not component pads, to bypass possible poor component pin solder joints.

[Rat_Patrol]

Seems to me you're blaming (and shaming) JLC without any actual evidence.

In addition, you seem to discard the possibility there might be a problem in your gerbers or design based on the assumption JLC is to blame. That's a dangerous approach. I personally would not be shipping products unless I knew *exactly* what the issue was. If JLC didn't flag a problem with your design, perhaps you should run it through some other vendors online verification to see if they catch anything. Or double check your design rules and DRC.

Just moving on is asking for trouble IMHO.

My order from PCBWay with the same gerber files sent are coming out just fine. I just put in a larger order from a vendor in South Korea, they didn't contact me yet about any issues with the gerbers.

Maybe there is something in my specs that doesn't get along with JLC that I missed, but as I said: I'm not interested in perusing this further when other fab houses can seemingly do what I need done without issue. If my gerbers were not within the capabilities of JLC, I would have hoped they would have let me know and not put out sub-standard parts.

For me, I don't have interest in "fixing" the issue since other PCB shops seemingly don't have an issue.

I still may use JLC for simpler 2 sided PCB prototypes, but no longer for my 4 layer boards.

[wraper]

Maybe there is something in my specs that doesn't get along with JLC that I missed, but as I said: I'm not interested in perusing this further when other fab houses can seemingly do what I need done without issue.

You refuse to understand there may be a problem with your design which makes it marginally stable. And PCB itself may have no issues.

[Rat_Patrol]

For a problem like random reboots, my bet would be something like marginal capacitance on a crystal oscillator or similarly sensitive node, maybe coupled with excessive track length which is slightly affected by variations between PCBs - e.g. lamination differences affecting capacitance.
Could even be something as basic as a floating input pin.

I actually thought that too. I was hell bent it had something to do with the crystal. I adjusted the crystal caps up and down pretty far (to the extreme points where the micro would not boot) and never found a value that fixed it.

Maybe it was something in my specs that didn't get along with JLC's tolerances, but I was never given any warnings of the sort when I made the orders.

[Microdoser]

you seem to discard the possibility there might be a problem in your gerbers or design

I recently had an issue where later designs of a board, one where I used discrete components instead of a daughterboard, did not work. It was a PCB to switch between other components using I2C. I checked with my scope and signals were getting through. For previous designs, I had shortened the cables and fitted my own 2.54mm Molex connector on the ends. Lately, I had decided to use the standard supplied cable even though it was a little too long because I didn't want to take my time up just crimping cables. None of the boards worked at all. I wondered whether I had made the right design for the discrete components, whether the extra length on the cable was affecting the signals or something else. I tried various values for pull-up resistors and some other changes but to no avail. I even considered manufacturing errors but there were no shorts and all signal paths were good. On the plus side, after many hours staring at a scope, I now have very good signal integrity

It took me a little while (too long) to realise that I had made two mistakes. One, I had swapped SDA and SCL on the board design, but the second mistake was I had done the same with the cables I had adjusted...

There was much self-chastisement and gnashing of teeth.

What are your design rules?

Personally, I make sure all my boards use the design rules supplied by JLCPCB for exactly this reason. I also make sure that if there are any holes for pins that they are oversized by the manufacturing tolerances plus a very little bit.

Maybe it was something in my specs that didn't get along with JLC's tolerances, but I was never given any warnings of the sort when I made the orders.

Well, unless you supply your specs to JLCPCB and ask them to check your specs against their tolerances (and pay them to do so) then, of course, they won't warn you about a problem they can't possibly predict.

They will just make the boards according to your gerbers, to within their stated tolerances, and any design problems that arise are beyond their control.

Of course, if the boards you received are out of their stated tolerances then you have a good case for getting a refund or replacement.

Are the boards you received out of their tolerance ranges?

[Rat_Patrol]

Maybe there is something in my specs that doesn't get along with JLC that I missed, but as I said: I'm not interested in perusing this further when other fab houses can seemingly do what I need done without issue.

You refuse to understand there might be a problem with your design which makes it marginally stable. And PCB itself may have no issues.

All my boards are tested at temps of -20c and +75c, put on a vibration table, and get at least 2 hours of operation before they ship. Only my orders from JLC were failing at such a rate.

[Rat_Patrol]

Thinking about some of the replies in this thread, I have a thought: copper thickness.

JLC's inner copper thickness is fixed at 0.5oz, where I always order 1.5oz from other vendors.

I wonder if that isn't the issue?

There are a few signal traces that unfortunately had to run on an inner layer.

Thoughts?

The boards that fail would boot up, but fail after running for about 5 minutes once they started "working". If I let them sit idle (without being hooked up to the test bench, just powered up the unit), they would run over-night without the rebooting issue.

[lutkeveld]

If you order with the same gerber, but different manufacturing options, its not really a fair comparison.
There might be something critical in your design that doesnt work on 0.5oz, but works on 1.5oz.

Before making this claim, its good to do a fair side by side comparison, with the same gerbers and ordering options.

[coppice]

For a problem like random reboots, my bet would be something like marginal capacitance on a crystal oscillator or similarly sensitive node, maybe coupled with excessive track length which is slightly affected by variations between PCBs - e.g. lamination differences affecting capacitance.
Could even be something as basic as a floating input pin.

Another common one is power is going through a really thin trace somewhere. Its so easy to miss a power trace that was treated like a signal trace during layout. It happens quite often, and boards get into production like that. One batch of boards may have traces a little on the fat side, and the resistance of the thin trace is not a killer. On the next batch the traces may be a little on the thin side, and the resistance causes quirks during moments of high current draw.

[mikeselectricstuff]

Thinking about some of the replies in this thread, I have a thought: copper thickness.

JLC's inner copper thickness is fixed at 0.5oz, where I always order 1.5oz from other vendors.

I wonder if that isn't the issue?

There are a few signal traces that unfortunately had to run on an inner layer.

Thoughts?

Plausible if something is already very marginal - decoupling etc. on a power supply.
Copper thickness on signal traces is highly unlikely to be an issue unless frequencies (or timing dependencies) are well into the several 100s of MHz range

The boards that fail would boot up, but fail after running for about 5 minutes once they started "working". If I let them sit idle (without being hooked up to the test bench, just powered up the unit), they would run over-night without the rebooting issue.

You need to understand exactly what "fail" means - you should be adding some debug instrumentation to the software to see if there is a particular place they are stopping to get a better idea of exactly what is failing.
Also try replacing the firmware with something very simple to narrow down the hardware that may be involved, though marginan failures can often be dependent on many interacting factors, so a better approach may be to cut out parts one by one to see if there is a point at which there is an obvious difference in behaviour.

[mkstevo]

I can only say I've had very good, consistent results with JLCPCB. I've ordered hundreds of boards from them. Some have been unusually shaped, some four layer, mostly two layer.

Of all the many boards we've had, one batch were manufactured "incorrectly". The problem boards had four plated holes in the corners for mounting screws. I decided on a whim to have these holes plating shaped octagonally, rather than circular. When delivered the octagonal holes had been partially rotated by about 30 degrees. This wouldn't have been a problem but for the fact that the shape for the copper planes on the top and bottom of the PCB had not been rotated to match. Thus the points of the hole plating lined up perfectly with the flat sections on top and bottom copper planes. This allowed the points to connect to both top and bottom copper layers, with the through hole plating connecting top to bottom. Top copper plane? 5V. Bottom copper plane? 0V. Thus my 5V and 0V were shorted together. Oops!

JLCPCB remanufactured the PCBs for free after I raised an issue, not before I had changed the hole shape to circular and they were of course perfect. Never used octagonal holes again. I did notice that all octagonal holes had the copper portion rotated by the same amount. In Eagle (version 7 at least) the pads for resistors and capacitors are octagonal and all these pads had been rotated but there was enough clearance between these and the ground planes for it not to be an issue. Just looked at some of the more recent boards I had delivered and they don't have any of the pads rotated.

[drussell]

Seems to me you're blaming (and shaming) JLC without any actual evidence.

In addition, you seem to discard the possibility there might be a problem in your gerbers or design based on the assumption JLC is to blame. That's a dangerous approach. I personally would not be shipping products unless I knew *exactly* what the issue was. If JLC didn't flag a problem with your design, perhaps you should run it through some other vendors online verification to see if they catch anything. Or double check your design rules and DRC.

Just moving on is asking for trouble IMHO.

My order from PCBWay with the same gerber files sent are coming out just fine. I just put in a larger order from a vendor in South Korea, they didn't contact me yet about any issues with the gerbers.

Maybe there is something in my specs that doesn't get along with JLC that I missed, but as I said: I'm not interested in perusing this further when other fab houses can seemingly do what I need done without issue. If my gerbers were not within the capabilities of JLC, I would have hoped they would have let me know and not put out sub-standard parts.

For me, I don't have interest in "fixing" the issue since other PCB shops seemingly don't have an issue.

Let me get this straight...  You have found an issue with a recent production run your product where using one particular PCB production run variant seems to show intermittent stability issues in the finished units.

Yet, instead of figuring out where the actual problem lies, which could quite possibly be something very marginal or outright defective in your original design that could well make the end products vulnerable to operational stability issues, you're seemingly content to just blame it on a "bad" PCB instead of realizing that something in your design is likely on the verge of totally failing to run properly all the time?!!   

Gee, I hope I never buy one of your gizmos...

[Ice-Tea]

Thinking about some of the replies in this thread, I have a thought: copper thickness.

JLC's inner copper thickness is fixed at 0.5oz, where I always order 1.5oz from other vendors.

I wonder if that isn't the issue?

There are a few signal traces that unfortunately had to run on an inner layer.

Thoughts?

The boards that fail would boot up, but fail after running for about 5 minutes once they started "working". If I let them sit idle (without being hooked up to the test bench, just powered up the unit), they would run over-night without the rebooting issue.

Check your power delivery.

- Fails on 0.5oz, works on 1.5oz
- Only fails when heavily loaded

Points, at least for me, to insufficiently wide power traces or planes/traces necked down by rows of vias or something. Let me also restate that it points to a marginal design. If tomorrow another supplier has a -10% tolerance on the copper thickness or on the copper width of the power trace or... you may well find yourself in trouble again. You need to understand why it works on a 1.5oz board and not on 0.5oz.

If you don't figure it out, it will remain a project that works by luck rather than by design.

[floobydust]

I had similar issues as OP with a Canadian fab- not JLC. Batch of 250 boards and about 25 had problems. Circuits didn't work or intermittent problems when flexed.
Traced it down to micro-shorts mostly between the ground-pour and adjacent traces, or between traces. PCB testing does not give 100% coverage, "flying lead" is just what you think.

When I dug in, there were tiny specs of copper here and there, I think from dust or lint at the photo-lithography stage. Etching was fine. I can't remember if the tiny specs were plated up.
The engineer who did the PCB layout did have tight spacing with the ground-pour ~0.2mm which aggravated the issue. (I can't find the pour-trace clearance spec for JLCPCB).

My conclusion was the PCB facility simply wasn't clean enough or had a dust problem that day.
I was quite pissed off after all the drama, it's always very painful dealing with PCB fab problems. But the board house gave me a credit towards the next order to make up for it.

Whether it's the PCB design or JLC, at least give them a chance instead of outright bashing them.

[Rat_Patrol]

Thinking about some of the replies in this thread, I have a thought: copper thickness.

JLC's inner copper thickness is fixed at 0.5oz, where I always order 1.5oz from other vendors.

I wonder if that isn't the issue?

There are a few signal traces that unfortunately had to run on an inner layer.

Thoughts?

The boards that fail would boot up, but fail after running for about 5 minutes once they started "working". If I let them sit idle (without being hooked up to the test bench, just powered up the unit), they would run over-night without the rebooting issue.

Check your power delivery.

- Fails on 0.5oz, works on 1.5oz
- Only fails when heavily loaded

Points, at least for me, to insufficiently wide power traces or planes/traces necked down by rows of vias or something. Let me also restate that it points to a marginal design. If tomorrow another supplier has a -10% tolerance on the copper thickness or on the copper width of the power trace or... you may well find yourself in trouble again. You need to understand why it works on a 1.5oz board and not on 0.5oz.

If you don't figure it out, it will remain a project that works by luck rather than by design.

Yup, I'll look it over and run some calculations. See what I can see. Maybe I can find something that works fine at 1oz and up but is sketchy at 0.50z pour.

When doing diagnostics, I had kept a scope on the power rail cap while I was going through this, and the 5v plane never moved when the micro would re-boot. I even kept the scope on the power pins for the micro, "perfect" 5 volts at all times (voltage deviated between 4.98 and 4.95v) while the micro would re-boot.

[langwadt]

Thinking about some of the replies in this thread, I have a thought: copper thickness.

JLC's inner copper thickness is fixed at 0.5oz, where I always order 1.5oz from other vendors.

I wonder if that isn't the issue?

There are a few signal traces that unfortunately had to run on an inner layer.

Thoughts?

The boards that fail would boot up, but fail after running for about 5 minutes once they started "working". If I let them sit idle (without being hooked up to the test bench, just powered up the unit), they would run over-night without the rebooting issue.

Check your power delivery.

- Fails on 0.5oz, works on 1.5oz
- Only fails when heavily loaded

Points, at least for me, to insufficiently wide power traces or planes/traces necked down by rows of vias or something. Let me also restate that it points to a marginal design. If tomorrow another supplier has a -10% tolerance on the copper thickness or on the copper width of the power trace or... you may well find yourself in trouble again. You need to understand why it works on a 1.5oz board and not on 0.5oz.

If you don't figure it out, it will remain a project that works by luck rather than by design.

Yup, I'll look it over and run some calculations. See what I can see. Maybe I can find something that works fine at 1oz and up but is sketchy at 0.50z pour.

When doing diagnostics, I had kept a scope on the power rail cap while I was going through this, and the 5v plane never moved when the micro would re-boot. I even kept the scope on the power pins for the micro, "perfect" 5 volts at all times (voltage deviated between 4.98 and 4.95v) while the micro would re-boot.

did you measure the ground at the micro?

[Rat_Patrol]

Seems to me you're blaming (and shaming) JLC without any actual evidence.

In addition, you seem to discard the possibility there might be a problem in your gerbers or design based on the assumption JLC is to blame. That's a dangerous approach. I personally would not be shipping products unless I knew *exactly* what the issue was. If JLC didn't flag a problem with your design, perhaps you should run it through some other vendors online verification to see if they catch anything. Or double check your design rules and DRC.

Just moving on is asking for trouble IMHO.

My order from PCBWay with the same gerber files sent are coming out just fine. I just put in a larger order from a vendor in South Korea, they didn't contact me yet about any issues with the gerbers.

Maybe there is something in my specs that doesn't get along with JLC that I missed, but as I said: I'm not interested in perusing this further when other fab houses can seemingly do what I need done without issue. If my gerbers were not within the capabilities of JLC, I would have hoped they would have let me know and not put out sub-standard parts.

For me, I don't have interest in "fixing" the issue since other PCB shops seemingly don't have an issue.

Let me get this straight...  You have found an issue with a recent production run your product where using one particular PCB production run variant seems to show intermittent stability issues in the finished units.

Yet, instead of figuring out where the actual problem lies, which could quite possibly be something very marginal or outright defective in your original design that could well make the end products vulnerable to operational stability issues, you're seemingly content to just blame it on a "bad" PCB instead of realizing that something in your design is likely on the verge of totally failing to run properly all the time?!!   

Gee, I hope I never buy one of your gizmos...

My boards are put through extremely rigorous testing prior to shipment, including extreme temps and vibration, along with a couple hours of running.
Even with the testing, all boards from JLC have been tagged with "replace upon warranty instead of repair" in my notes (all boards are serialized and tracked with build info/notes) in case any ever come back, which very seldom happens.

[Rat_Patrol]

Thinking about some of the replies in this thread, I have a thought: copper thickness.

JLC's inner copper thickness is fixed at 0.5oz, where I always order 1.5oz from other vendors.

I wonder if that isn't the issue?

There are a few signal traces that unfortunately had to run on an inner layer.

Thoughts?

The boards that fail would boot up, but fail after running for about 5 minutes once they started "working". If I let them sit idle (without being hooked up to the test bench, just powered up the unit), they would run over-night without the rebooting issue.

Check your power delivery.

- Fails on 0.5oz, works on 1.5oz
- Only fails when heavily loaded

Points, at least for me, to insufficiently wide power traces or planes/traces necked down by rows of vias or something. Let me also restate that it points to a marginal design. If tomorrow another supplier has a -10% tolerance on the copper thickness or on the copper width of the power trace or... you may well find yourself in trouble again. You need to understand why it works on a 1.5oz board and not on 0.5oz.

If you don't figure it out, it will remain a project that works by luck rather than by design.

Yup, I'll look it over and run some calculations. See what I can see. Maybe I can find something that works fine at 1oz and up but is sketchy at 0.50z pour.

When doing diagnostics, I had kept a scope on the power rail cap while I was going through this, and the 5v plane never moved when the micro would re-boot. I even kept the scope on the power pins for the micro, "perfect" 5 volts at all times (voltage deviated between 4.98 and 4.95v) while the micro would re-boot.

did you measure the ground at the micro?

Excellent point, no I didn't. I have a ground access pin that I used for the scope probe. That said, there is a LOT of ground access. From calculations I just ran, I have enough ground capacity for the internal ground plane for 2.25 amps. The system can only produce 1 amp of power for the +5v ground plane.

Just ran the calculations for 0.50z internal pour to the +5v plane, and the connections have enough capacity for 1.25 amps with a voltage drop of .019v. Not sure that is the issue there either.

I'm wondering if there was enough copper on some vital via? I am running vias at the minimum for JLC.

[langwadt]

Thinking about some of the replies in this thread, I have a thought: copper thickness.

JLC's inner copper thickness is fixed at 0.5oz, where I always order 1.5oz from other vendors.

I wonder if that isn't the issue?

There are a few signal traces that unfortunately had to run on an inner layer.

Thoughts?

The boards that fail would boot up, but fail after running for about 5 minutes once they started "working". If I let them sit idle (without being hooked up to the test bench, just powered up the unit), they would run over-night without the rebooting issue.

Check your power delivery.

- Fails on 0.5oz, works on 1.5oz
- Only fails when heavily loaded

Points, at least for me, to insufficiently wide power traces or planes/traces necked down by rows of vias or something. Let me also restate that it points to a marginal design. If tomorrow another supplier has a -10% tolerance on the copper thickness or on the copper width of the power trace or... you may well find yourself in trouble again. You need to understand why it works on a 1.5oz board and not on 0.5oz.

If you don't figure it out, it will remain a project that works by luck rather than by design.

Yup, I'll look it over and run some calculations. See what I can see. Maybe I can find something that works fine at 1oz and up but is sketchy at 0.50z pour.

When doing diagnostics, I had kept a scope on the power rail cap while I was going through this, and the 5v plane never moved when the micro would re-boot. I even kept the scope on the power pins for the micro, "perfect" 5 volts at all times (voltage deviated between 4.98 and 4.95v) while the micro would re-boot.

did you measure the ground at the micro?

Excellent point, no I didn't. I have a ground access pin that I used for the scope probe. That said, there is a LOT of ground access. From calculations I just ran, I have enough ground capacity for the internal ground plane for 2.25 amps. The system can only produce 1 amp of power for the +5v ground plane.

Just ran the calculations for 0.50z internal pour to the +5v plane, and the connections have enough capacity for 1.25 amps with a voltage drop of .019v. Not sure that is the issue there either.

I'm wondering if there was enough copper on some vital via? I am running vias at the minimum for JLC.

if you have a failing board should be easy to check, scope on gnd/vcc on decoupling cap on the micro, or beef up the gnd to the micro with a bodge wire

[thm_w]

I can only say I've had very good, consistent results with JLCPCB. I've ordered hundreds of boards from them. Some have been unusually shaped, some four layer, mostly two layer.

Of all the many boards we've had, one batch were manufactured "incorrectly". The problem boards had four plated holes in the corners for mounting screws. I decided on a whim to have these holes plating shaped octagonally, rather than circular. When delivered the octagonal holes had been partially rotated by about 30 degrees. This wouldn't have been a problem but for the fact that the shape for the copper planes on the top and bottom of the PCB had not been rotated to match. Thus the points of the hole plating lined up perfectly with the flat sections on top and bottom copper planes. This allowed the points to connect to both top and bottom copper layers, with the through hole plating connecting top to bottom. Top copper plane? 5V. Bottom copper plane? 0V. Thus my 5V and 0V were shorted together. Oops!

JLCPCB remanufactured the PCBs for free after I raised an issue, not before I had changed the hole shape to circular and they were of course perfect. Never used octagonal holes again. I did notice that all octagonal holes had the copper portion rotated by the same amount. In Eagle (version 7 at least) the pads for resistors and capacitors are octagonal and all these pads had been rotated but there was enough clearance between these and the ground planes for it not to be an issue. Just looked at some of the more recent boards I had delivered and they don't have any of the pads rotated.

The octagonal thing was discussed here as well: https://www.eevblog.com/forum/manufacture/jlc-pcb-reorientation-of-octagonal-pads/

[phil from seattle]

Wow, they still haven't fixed the octagonal pad problem.  I changed to round just to use JLCPCB so it doesn't bother me but they really do need to fix that problem.

The gerbers work fine with another manufacturer point.  Gerbers aren't created equal - there are a number of issues you need to deal with.  When I switched to from eagle to kicad, I discovered that gerbers that JLCPCB accepts choke OSHpark.  And the ones that OSHPark accepts choke JLCPCB.  With Eagle, by the way, both companies accepted and build with the same gerber file just fine.

[jmelson]

As I said above though, you have to pay extra for it (as an option) if you want 100% test. Otherwise they will just do random test of a few panels in the batch.

OOOHHHH!  Never again!  MANY decades ago, I disqualified a bunch of US fabricators when I paid for electrical test, and they spot-checked a few 4-layer boards and then sent the lot to me.  Two-layer is mostly OK, I can fix a short on those.  But, when there's an internal short on a 4-layer board, it is a REAL PAIN to fix it after the parts are stuffed.  So, that was my cardinal sin, paying for test and then not actually checking them.  I would never use that company again.

I can imagine getting away with no test on a simple, 2-layer board, but I'd NEVER, EVER do that on a multilayer.

PCBway is slightly more expensive, but they DO the testing, and I look for the prick marks.

Jon

[Mangozac]

I can imagine getting away with no test on a simple, 2-layer board, but I'd NEVER, EVER do that on a multilayer.

You would have to be mad to not get a 4-layer board fully tested! I don't worry about full testing on simple 2 layer designs but for anything approaching any of the JLC design rules or just a higher value product 100% testing is a must.

[floobydust]

"1/2 oz." copper has a range - it's not always 18µm and some fabs do skimp. For an inner layer of 18µm nominal copper thickness, IPC-A-600J Class 1&2 accepts a minimum of 11.4 µm after manufacture, IPC-4562 is 15.4µm min.

What standards are the boards built to, do we know? IPC membership does not mean the standards are followed or independently audited.

I've sent PC boards to Japan to get micro-section analysis and verify a laminate was genuine, and the finished copper thickness, wall plating was in spec. as I was having problems with the controlled impedances and Dk being way off.

[thinkfat]

First thing, before stuffing the board, put it under a microscope or strong magnifier, and look for the probe marks on the pads.  The flying probe tester leaves a TINY dimple in the center of each pad when it tests the board.  If you don't see probe marks, the board was NOT TESTED!

As I said above though, you have to pay extra for it (as an option) if you want 100% test. Otherwise they will just do random test of a few panels in the batch.

Really? I was not aware of that. When ordering from JLCPCB, you can only opt out on testing, but at least for two and four layer boards it doesn't make any difference in price or manufacturing time. Where's the option to have 100% testing?

[Siwastaja]

The problem here is the lack of investigation into the problem, and fixation into thinking a statistical guess means anything.

Statistical analysis (boards ordered from JLC do not work as often, board ordered elsewhere work more often) is completely meaningless. I can start giving it some weight after we are talking about tens of thousands of boards ordered from dozens of different fabs and seeing large differences, and even then, it isn't proof of anything, just a hint. At this level, it isn't even a hint.

Need to investigate more. There is no magic sauce for this, it takes time and expertise.

I was once almost sure I have a manufacturing problem (PCB or soldering) because out of batch of 30 identical boards, a few boards failed to initialize an accelerometer. SDA, SCL or power must be flaky! Guess what? Pure software problem. All same ICs, software behaving 1:1 the same, some ST accelerometer units fail to work. Initialization sequence changed, now they all work.

[Microdoser]

Check your power delivery.

- Fails on 0.5oz, works on 1.5oz
- Only fails when heavily loaded

Points, at least for me, to insufficiently wide power traces or planes/traces necked down by rows of vias or something. Let me also restate that it points to a marginal design. If tomorrow another supplier has a -10% tolerance on the copper thickness or on the copper width of the power trace or... you may well find yourself in trouble again. You need to understand why it works on a 1.5oz board and not on 0.5oz.

If you don't figure it out, it will remain a project that works by luck rather than by design.

Let's have a look at some of the numbers.

The system can only produce 1 amp of power for the +5v ground plane.
Just ran the calculations for 0.50z internal pour to the +5v plane, and the connections have enough capacity for 1.25 amps with a voltage drop of .019v. Not sure that is the issue there either.

I'm wondering if there was enough copper on some vital via? I am running vias at the minimum for JLC.

You have a 25% headroom capacity in your design

"1/2 oz." copper has a range - it's not always 18µm and some fabs do skimp. For an inner layer of 18µm nominal copper thickness, IPC-A-600J Class 1&2 accepts a minimum of 11.4 µm after manufacture, IPC-4562 is 15.4µm min.

What standards are the boards built to, do we know? IPC membership does not mean the standards are followed or independently audited.

I've sent PC boards to Japan to get micro-section analysis and verify a laminate was genuine, and the finished copper thickness, wall plating was in spec. as I was having problems with the controlled impedances and Dk being way off.

the '18um' inner layer could be less than 2/3 the thickness and still be within IPC-A-600J Class 1&2. That is more than your headroom allows.

If your design works with companies that have the option of thicker inner layers then it seems very likely that your design is out of spec for 0.5 oz inner layers.

IMO If you beef up your inner layer tracks and maybe didn't use the very smallest vias allowed in the design rules, you would get reliably working boards from JLCPCB.

Personally, I try to never approach the limits of production, I like to have some margin for error in my designs if for no other reason than it gives the product extra reliable lifespan when it starts to show signs of age.

If it is running close to the limits when new then any degradation of function means it will fail early.

[olkipukki]

in those ways, JLCPCB can make the quality complaint rate to be 0.25%(In the 20,000 orders, there is less than 50 orders with quality complaints).

That's quite impressive rate 

What is actually 'quality complaint'? 

Let's say somebody 'played' with stencil apertures  or solder masks are way off as requred, so orders back to the house to be redone again - does it qualified for 'quality complaints'?

[JohnnyMalaria]

First thing, before stuffing the board, put it under a microscope or strong magnifier, and look for the probe marks on the pads.  The flying probe tester leaves a TINY dimple in the center of each pad when it tests the board.  If you don't see probe marks, the board was NOT TESTED!

As I said above though, you have to pay extra for it (as an option) if you want 100% test. Otherwise they will just do random test of a few panels in the batch.

Really? I was not aware of that. When ordering from JLCPCB, you can only opt out on testing, but at least for two and four layer boards it doesn't make any difference in price or manufacturing time. Where's the option to have 100% testing?

For the order with a quantity of no more than 50 pieces, we will provide full test for the whole order for free.

For the order with a quantity equal to or bigger than 50 pieces, it will cost you an extra fee for full test, the extra test cost can be calculated on our website.

https://jlcpcb.com//quote/pcbOrderFaq/Flying%20probe%20test

[Rat_Patrol]

I took the JLC boards under magnification, they were tested.

I did pay for the extra 4 wire Kelvin testing though, so they should be tested.

[Rat_Patrol]

Check your power delivery.

- Fails on 0.5oz, works on 1.5oz
- Only fails when heavily loaded

Points, at least for me, to insufficiently wide power traces or planes/traces necked down by rows of vias or something. Let me also restate that it points to a marginal design. If tomorrow another supplier has a -10% tolerance on the copper thickness or on the copper width of the power trace or... you may well find yourself in trouble again. You need to understand why it works on a 1.5oz board and not on 0.5oz.

If you don't figure it out, it will remain a project that works by luck rather than by design.

Let's have a look at some of the numbers.

The system can only produce 1 amp of power for the +5v ground plane.
Just ran the calculations for 0.50z internal pour to the +5v plane, and the connections have enough capacity for 1.25 amps with a voltage drop of .019v. Not sure that is the issue there either.

I'm wondering if there was enough copper on some vital via? I am running vias at the minimum for JLC.

You have a 25% headroom capacity in your design

"1/2 oz." copper has a range - it's not always 18µm and some fabs do skimp. For an inner layer of 18µm nominal copper thickness, IPC-A-600J Class 1&2 accepts a minimum of 11.4 µm after manufacture, IPC-4562 is 15.4µm min.

What standards are the boards built to, do we know? IPC membership does not mean the standards are followed or independently audited.

I've sent PC boards to Japan to get micro-section analysis and verify a laminate was genuine, and the finished copper thickness, wall plating was in spec. as I was having problems with the controlled impedances and Dk being way off.

the '18um' inner layer could be less than 2/3 the thickness and still be within IPC-A-600J Class 1&2. That is more than your headroom allows.

If your design works with companies that have the option of thicker inner layers then it seems very likely that your design is out of spec for 0.5 oz inner layers.

IMO If you beef up your inner layer tracks and maybe didn't use the very smallest vias allowed in the design rules, you would get reliably working boards from JLCPCB.

Personally, I try to never approach the limits of production, I like to have some margin for error in my designs if for no other reason than it gives the product extra reliable lifespan when it starts to show signs of age.

If it is running close to the limits when new then any degradation of function means it will fail early.

Yup, looking like a very good possibility of why JLC's boards sometimes work, sometimes don't with the "allowable" swing of inner layer thickness.

For this design, I will just keep going with another manufacturer with thicker inner layers instead of go over with a board re-design. I generally only use Chinese manufacturers until I'm satisfied with a board design, than switch over to South Korean manufacture for larger lots.

[mikeselectricstuff]

Yup, looking like a very good possibility of why JLC's boards sometimes work, sometimes don't with the "allowable" swing of inner layer thickness.

For this design, I will just keep going with another manufacturer with thicker inner layers instead of go over with a board re-design. I generally only use Chinese manufacturers until I'm satisfied with a board design, than switch over to South Korean manufacture for larger lots.

You still really need to get to the bottom of exactly why your design is so sensitive to layer thickness to have any confidence that this is the real issue, and you've actually fixed it.

[mkstevo]

Wow, they still haven't fixed the octagonal pad problem.  I changed to round just to use JLCPCB so it doesn't bother me but they really do need to fix that problem.

Well, the most recent boards I had done (September 2020) are certainly correct. I did make a mental note to never use octagonal "holes" again though...

[Siwastaja]

Yes, I have hard time believing a 0.5oz inner layer would be the cause. It's possible, but right now, it's just another guess out of thin air, don't fixate onto that. Investigate!

Compare this to police/detective work. They indeed look for differences such as layer thickness here, but they are considered just hints to steer the investigation, they are not proof, and I bet in 99% cases, such hints end up being dead ends, but finally one of them leads to the proof.

[JLCPCB Official]

in those ways, JLCPCB can make the quality complaint rate to be 0.25%(In the 20,000 orders, there is less than 50 orders with quality complaints).

That's quite impressive rate 

What is actually 'quality complaint'? 

Let's say somebody 'played' with stencil apertures or solder masks are way off as requred, so orders back to the house to be redone again - does it qualified for 'quality complaints'?

hello, olkipukki, when people are satisfied with our PCB or our services, they will not complain. Our low rate of quality complaints means that our products and services are satisfactory.

 For your case, my understanding is someone shrink or expands the aperture size for solder paste layer (used to make stencil for SMT) intentionally. Of course he can submit a quality complaint, however, we will not be responsible for it. Do you mean in this way?

[Attorney]

Maybe it was something in my specs that didn't get along with JLC's tolerances, but I was never given any warnings of the sort when I made the orders.

I think it's a valid point.  Each PC board vendor should check the Gerber file parameters against their own allowable tolerances.  If it's out of spec, there should be a warning along with an opportunity to abort -- or proceed with the order.

Paul

[JohnnyMalaria]

Maybe it was something in my specs that didn't get along with JLC's tolerances, but I was never given any warnings of the sort when I made the orders.

I think it's a valid point.  Each PC board vendor should check the Gerber file parameters against their own allowable tolerances.  If it's out of spec, there should be a warning along with an opportunity to abort -- or proceed with the order.

Paul

You have the option to pay an extra $0.54 to be sent the production files so you can check and confirm them prior to production. Maybe there's something that could have been spotted.

[cgroen]

Maybe it was something in my specs that didn't get along with JLC's tolerances, but I was never given any warnings of the sort when I made the orders.

I think it's a valid point.  Each PC board vendor should check the Gerber file parameters against their own allowable tolerances.  If it's out of spec, there should be a warning along with an opportunity to abort -- or proceed with the order.

Paul

JLCPCB does exactly that. I have a couple of times been caught by the engineers at JLCPCB before I got my design rules set correct. In both cases it was length matching, the spacing between the "waves" were below their minimum clearance (3.5mil). Both times they sent me pictures from their check and opened the orders so I just could upload new gerbers.

[Microdoser]

Maybe it was something in my specs that didn't get along with JLC's tolerances, but I was never given any warnings of the sort when I made the orders.

I think it's a valid point.  Each PC board vendor should check the Gerber file parameters against their own allowable tolerances.  If it's out of spec, there should be a warning along with an opportunity to abort -- or proceed with the order.

Paul

From my experience JLCPCB does this, if your gerber is out of their manufacturing specs they will let you know. One time they got in touch because I had included a paste layer from an old design by accident so rather than just send me the wrong stencil, they confirmed whether I wanted the stencil to be made from the paste layer or from the board gerber.

What they can't reasonably be expected to possibly know is if your design will fail because your gerbers, when made to their stated tolerances, fall outside of your own design specs. For example if your design needs 1 amp to travel along particular tracks but when manufactured this is not possible or causes board reliability issues.

It would be a very costly service indeed if they did that level of checking.

[JLCPCB Official]

In order to align some points we confirm the following details :
JLCPCB provides a files inspection option before payment which means that you don't have to pay for your order until we confirm the audit results of our DFM checker (please note that in such case the order will not enter to production cycle until it gets paid).
You can refer to the following official JLCPCB source to get the information :
10th section"Review Before Payment"
https://support.jlcpcb.com/article/21-how-do-i-place-an-order#:~:text=Review%20Before%20Payment&text=Your%20design%20will%20not%20be,order%20will%20be%20canceled%20automatically.

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In case the design files is out of JLCPCB capabilities the order will be directly canceled and the support team will immediately send a notification Email about the details related to the cancellation of the order, and it gives also the hand to the customer to update the design files by uploading new ones and it will be reviewed as well.
You can refer to the following official JLCPCB source to learn more about this point :
https://support.jlcpcb.com/article/68-instructions-for-ordering

" alt="" class="bbc_img" />

In some cases when JLCPCB engineers prepare the production files they could notice some suspected design issues, in such case customers will receive a notification Email to confirm the design (please note that this is not the responsibility of JLCPCB engineers because JLCPCB don't check the PCB design itself but we check the DRC that needs to match JLCPCB capabilities). So please verify your design before placing the order just to be sure that everything will be ok.
About the Quality Complaint feature, every customer has the right to start a quality complain and we treat it seriously through our quality inspection team (yes there is a whole team for this purpose), you can start this quality complain by sending Email to lilyyang@jlcpcb.com in this Email you can describe the issue and the team will guide you all along this process
Please check the following official JLCPCB link to learn more about JLCPCB contact :
https://support.jlcpcb.com/article/45-contact-jlcpcb

" alt="" class="bbc_img" />

For any specific guidance you can Email us through support@jlcpcb.com

Thank you for this constructive topic 

[Alex Eisenhut]

Any power supplies/regulators have a sense line on your design?

[floobydust]

How thick is the copper? What quality standard does JLC use?

APC adds a test coupon right on the PC board to confirm copper thickness in their UPS designs.

[JLCPCB Official]

JLCPCB uses a FR-4 Standard Tg 130-140/ Tg 155
The copper thickness is not the same for outer and inner copper Layer :

• Finished Outer Layer Copper   1 oz/2 oz (35um/75um)   Finished copper weight of outer layer is 1oz or 2oz.
• Finished Inner Layer Copper   0.5 oz (17um)   Finished copper weight of inner layer is 0.5oz only.

Considering the above details you can see that the thickness for outer Layer copper for 1 oz/2 oz board is respectively 0.35mm/0.75mm and the thickness for inner Layer copper 0.5 oz is 0.17mm.    

Kindly check the following link of JLCPCB capabilities (official webpage), you will find in the "PCB specifications" section the details related to the FR-4 material used to produce JLCPCB PCBs and its related specifications.
Link : https://jlcpcb.com/capabilities/Capabilities

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