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

[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

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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

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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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