Help... problem with PCB manufacturer

[ela_ela]

Hello,

as long time reader I am thrilled to see how much help is done to each other in this community forum.

My problem:
I was looking for a PCB manufacturer who can handle soldermask between SMT pads. Space between the copper is 0.3mm.
I asked Seeed, Elecrow, ITead, PCBWay, PCBCart, PCBWay, Shenzhen2u and dirtybcp. They all rejected my order.

Then I found one, he answered:
> The minimum recommended width of lines of soldermask is 4mil (0.1mm).
> If a soldermask line is less than 4mil, the line may be torn off during manufacture.
> So 0.3mm is no problem.

I ordered 10 boards and paid with PayPal. They were delivered after some weeks.
 !! No soldermask between 0.3mm SMT pads. Between 0.35mm and 0.4mm are fine.

So I complained and the manufacturer answered:
> You need to show me that you are having a real problem because of this.
> Yes you have a real problem.  Is it because of no soldermask there?  No.
> It's not unusual for small changes to be made on the board.
> Just because it's easy to come talk to me, why make this my problem?

I asked particularly for this specification and he accepted.

Please help... what should I do now?

Many thanks,
Manuela

[ataradov]

The only thing you can do is to explore PayPal policies on things like that, but I don't think there is a lot of hope.

There is no way to get some low life bastard in China.

[forrestc]

So... just a question (as I've fallen into a similar trap in the past):

Did you include the instruction NOT to remove the solder mask on that part in a readme or other file with the gerbers themselves AND include a note to this effect in the email or whatever other method you used to submit the gerbers?

PCB manufacturers change gerbers all the time to make the boards more manufacturable on their end.  They've learned over the years what they need to do to do this.   Things like removing silkscreen (legend) which covers a pad, fixing annuar ring sizes, rounding off too-sharp corners which will cause etchant traps, etc., etc., etc.    And yes, removing very small solder mask between pads.  As a result, boards are rarely printed using the exact version of the gerber provided by the customer.

If you were verbose about your requirements, and ALSO provided that documentation with the gerbers themselves (i.e. in the zip file), then they should probably fix it. 

On another note:  Is there a specific reason why you need solder mask between the pads?   I originally thought that the mask between the pads was better, but I've discovered over the years that on small pitch leaded components it simply isn't needed - and in some cases the boards with the solder mask have more issues especially if the solder mask isn't adhered very well to the boards.   With that fine of pitch the mask just doesn't have that much effect.

Hello,

as long time reader I am thrilled to see how much help is done to each other in this community forum.

My problem:
I was looking for a PCB manufacturer who can handle soldermask between SMT pads. Space between the copper is 0.3mm.
I asked Seeed, Elecrow, ITead, PCBWay, PCBCart, PCBWay, Shenzhen2u and dirtybcp. They all rejected my order.

Then I found one, he answered:
> The minimum recommended width of lines of soldermask is 4mil (0.1mm).
> If a soldermask line is less than 4mil, the line may be torn off during manufacture.
> So 0.3mm is no problem.

I ordered 10 boards and paid with PayPal. They were delivered after some weeks.
 !! No soldermask between 0.3mm SMT pads. Between 0.35mm and 0.4mm are fine.

So I complained and the manufacturer answered:
> You need to show me that you are having a real problem because of this.
> Yes you have a real problem.  Is it because of no soldermask there?  No.
> It's not unusual for small changes to be made on the board.
> Just because it's easy to come talk to me, why make this my problem?

I asked particularly for this specification and he accepted.

Please help... what should I do now?

Many thanks,
Manuela

[ela_ela]

...
Did you include the instruction NOT to remove the solder mask on that part in a readme or other file with the gerbers themselves AND include a note to this effect in the email or whatever other method you used to submit the gerbers?
...
If you were verbose about your requirements, and ALSO provided that documentation with the gerbers themselves (i.e. in the zip file), then they should probably fix it.
...

The seller doesn't allow anything else but gerber files in the zip file.
> ..., so you can't put instructions inside a layer or layer names in the filenames or in a readme file. ...

I asked for special instructions: 0.3mm with soldermask, he said ok and I replied with the zip file, which he accepted.

[Falcon69]

The only thing you can do is contact PayPal, file a dispute saying that the product received was not as described or agreed upon by the seller.

If you contact them threatening to tell people on the net who they are if they don't refund money or replace the boards, PayPal/eBay will rule in favor of them. You can't threaten the seller or bribe them in anyway, just facts.

After it is all sorted out, PM me who it is, so I don't make a mistake with them.

[Bassman59]

After it is all sorted out, PM me who it is, so I don't make a mistake with them.

Let us ALL know who to avoid!

[Christopher]

Edit to remove the manufacturer name.

Should be obvious if you Google some quotes from this topic.

[Jeroen3]

You can add a docu layer. This can have comments, dimensions and other remarks.

If you do buy from a pcb farm that will have you specify in which class they should manufacture, you will know what you will get.
Such as eurocircuits, or another EU based company.

[free_electron]

Hello,

as long time reader I am thrilled to see how much help is done to each other in this community forum.

My problem:
I was looking for a PCB manufacturer who can handle soldermask between SMT pads. Space between the copper is 0.3mm.
I asked Seeed, Elecrow, ITead, PCBWay, PCBCart, PCBWay, Shenzhen2u and dirtybcp. They all rejected my order.

And for good reason ... you are asking for problems.

4mil is NOT 0.1mm !!! it is 0.102
You need a gap of 0.306 mm to do that. you had 0.3.  gerbers are processed by machines. if the rule is set to minimum gap 4 mil ... 0.3mm is below that and will get stripped.

for such fine isolation slivers other rules come into play. it depends also how long that sliver is. a short sliver may work , a long one may peel off.

Then there is the registration accuracy they have for soldermask on board.

I know you asked explicitly if they could do that but : cheap proto's and high quality , high resolution don't go together.
If you really need such small soldermask you should have gone with a specialized board house and not shopping around for a cheapo chinese like itead et al ( nothing wrong with itead , i use them very often for proto's. but if i make a board with 4mil track and gap ...i use PCBway. below that : sierra proto express or gorilla circuits at a 50x fold cost)

[mrpackethead]

Then there is the registration accuracy they have for soldermask on board.

I got a bit bitten by PCBway on this, their mask registration was pretty ugly on a run of boards i had, ( to the point the mask was over pads! )

[ela_ela]

And for good reason ... you are asking for problems.

4mil is NOT 0.1mm !!! it is 0.102

If the reseller had said that 12mil distance is the minimum, I had reduced the pads and changed my soldermask rules.

I know you asked explicitly if they could do that but : cheap proto's and high quality , high resolution don't go together.
If you really need such small soldermask you should have gone with a specialized board house and not shopping around for a cheapo chinese like itead et al ( nothing wrong with itead , i use them very often for proto's. but if i make a board with 4mil track and gap ...i use PCBway. below that : sierra proto express or gorilla circuits at a 50x fold cost)

I learned my lesson. Never use a reseller again, but Asia manufacturers seem to be ok.

I did my prototype at eurocircuits. They do as standard technology:
  pad <> 0.06mm space <> 0.18mm soldermask <> 0.06mm space <> pad
And I do know now, that soldermask isn't necessary between pads to solder them by hand without bridges.

But for 100+ boards to give away, eurocircuits is to expensive.
So I was looking for cheaper manufacturer. And found one which knows mm and mil and does the 0.1mm soldermask.
The best thing is that I got twice the amount of boards for the same price I paid to the reseller.

[mrpackethead]

just start with a few cheap low cost boards and see how you go.

[Simon]

They should have said that it cannot be done, usually they do, they just wanted your business. On the other had why did you beleive that despite all the well known ones refusing to do it that this one could ? When I send boards off to be made I get an email asking about the changes that need to be made.

[ela_ela]

They should have said that it cannot be done, usually they do, they just wanted your business. On the other had why did you beleive that despite all the well known ones refusing to do it that this one could ?

They were one of two who responded to my requirements with ok. And they are well known and have a good reputation.
After I received my boards, another customer told me that they use different factories. And have done boards with 0.025mm soldermask clearance... for no extra costs.

[Simon]

there are different degrees of accuracy you can get boards done to, it costs more to have them more accurate, I usually work to 0.152mm and have no problems.

[hackvana]

After it is all sorted out, PM me who it is, so I don't make a mistake with them.

Let us ALL know who to avoid!

The person to avoid is Hackvana, that guy is a complete scammer!  Oh wait, it's me.

(special shout out to ataradov: I'm not a low life bastard in China, I'm a westerner in Australia)

There are many things that ela_ela didn't mention in his message, and several things where he's quoted a private conversation in public, and quoted me out of context.  I hope you'll allow me to set the record straight.

The actual problem he had was that when his assembly company loaded the components, there was bridging between pads of the resistor networks.  It's an annoying problem, and I feel for him.

ela_ela's soldermask request was specifically regarding the slivers between the pads of the resistor networks.  These slivers, while not anywhere too thin, were removed by the factory.

Here's a picture of a board I did for another customer (shown with permission):

 

If you look carefully, you can see there's no soldermask between the pads.

For scale, the slot is 0.8mm wide.  Original here:

(That customer said that he didn't have any problems with solder bridges)

ela_ela told me that in his opinion, the solder bridges were caused by the removal of the soldermask, and his gripe is that if the factory hadn't removed the soldermask, there wouldn't have been bridges.  How dare the factory change his design!

There are two misconceptions which I wish ela_ela understood.  (My chat logs say that I've spent more than two hours helping him understand this, but without success)

The first misconception is thinking that in PnP manufacture, bridges are avoided with soldermask.  Not so.  Bridges are prevented by having the right amount of solder paste.  Here's a pic from an SMTA presentation:



Note that for NSMD (non-soldermask defined) pads, the soldermask doesn't touch the pad.



Note the term "aperture-pad gasketing".  That's right, there should be a seal between the side of the stencil aperture, and the pad.  Solder paste should not escape.



And you can see here that the solder paste is only on the pad. 

(Full document: http://www.smta.org/chapters/files/Houston_Troubleshooting_The_Stencil_Printing_Process_-_Chrys_Shea.pdf
)

There's an appnote by Atmel that in section 3.7.2, talks about soldermask and fine pitch chips:

http://www.atmel.com/images/atmel-8826-seeprom-pcb-mounting-guidelines-surface-mount-packages-applicationnote.pdf

Regarding soldermask between pads, it says:

the web has to be at least 75 microns in width for the solder mask to stick to the PCB surface

If the soldermask is finer, the slivers can break, like this:



Broken slivers can cause soldering problems.

And the app note talks about fine pitch chips:

for finer pitch parts, not enough space is available for the solder mask web
in between the pads. In such cases, it is recommended to use the trench type solder mask opening where a big opening is designed around all the pads on each side of the package with no solder mask in between the pads

So, fine pitch chips can be soldered with no bridges, without soldermask.  The secret is having the right amount of paste on the pads.  And that depends on the thickness of the stencil, and the size of the stencil aperture.

The second misconception is the idea that what's in your files is what's should be used to make the product.  In reality, PCB and stencil factories change the data they receive more than you realise, and for good reason.  It's partly to fit your data to the processes they use, and partly because they have years of experience in manufacturing, and they know what works.

Here's what the stencil factory does when they receive your data:

• Check your input files for readability.
• Apply heuristics to match your aperture data to known component sizes.
• Calculate the optimum paste volume and shape for each pad:
   
  • To prevent solder bridges, aperture size may be reduced.
  • To get good joints, aperture size may be increased.
  • To help with paste release, the shape of the apertures can be modified a little.   For example, the ends of rectangular apertures for IC pads are rounded.

The stencil factory also segments and reduces the paste area of large pads.

So what we're seeing here is a difference between CAD (the design) and CAM (what's necessary to make it).  The factory uses their expertise to make changes that lead to better manufacturability.

Let's look at an example for a stencil I supplied recently: (used with permission of customer)



You can see the changes that have been made.  The under-chip apertures have been "segmented" to prevent too much solder, and the apertures for the pads have been given rounded ends, which helps with paste release when the stencil is lifted.

In the vast majority of cases, the changes made by the factory are helpful.  They make manufacturing your product easier.  It's a good thing.

There are standards for how stencil thickness and aperture size should be computed (IPC-7525B).  Certainly, a stencil aperture which is the same size as the pad is too big.  You'll get too much solder paste.

ela_ela got his stencil through the assembler (not through me).  I asked him for the the GBP (bottom paste) file to match his GBL (bottom copper) file.  He finally supplied it.  Here's the two of them superimposed:



What we see here is that the apertures in the GBP file are exactly the same size as in the GBL file.  That's not necessarily a problem, because as mentioned, something the stencil factory should do is resize the apertures.  But what if the stencil company didn't resize the apertures?  What would happen is that there'd be too much solder on the pads, which would lead to bridges.  Hmm.  That's my hypothesis for what happened.  His problem is not missing soldermask, but unresized apertures.  As much as he'd like the two to be related, they're not.  Correlation does not imply causation.

I showed a picture before with the CAD and CAM version of a GTP file.  A way to test my hypothesis is for ela_ela to ask his assembler for the CAM version of his GTP file, but he refused, saying "there is no assembly company anymore.  they quit".

Say what?  Why would an assembler quit?  I'll let you draw your own conclusions.

So let's wrap up where we're at with this:

• CAD != CAM, and factories make subtle changes to PCB and stencil data for several reasons, which is often done to improve manufacturability.
• With PnP, soldermask is not for preventing solder bridges.
• Solder bridges are prevented by not having too much solder.
• Stencil apertures should be resized to deliver the right amount of paste.

Without an assembler to pin blame on, he's trying to pin blame on the next nearest thing: me.  When I offered a credible explanation for the cause of the problem, he wasn't able to listen and learn.  Instead, he came here.

I've done this job for five years, I work hard at providing good service to my customers, and I have a busy IRC channel with many satisfied customers.

Let's not be so quick to judge.  You can't know the whole story until you've heard both sides.

Mitch.

[aandrew]

I was looking for a PCB manufacturer who can handle soldermask between SMT pads. Space between the copper is 0.3mm.
I asked Seeed, Elecrow, ITead, PCBWay, PCBCart, PCBWay, Shenzhen2u and dirtybcp. They all rejected my order.

There's a very good reason for this, and I'm positive that any vendor who rejects your order because of this would have explained it to you.

Soldermask is brittle and thin. These thin features will not stick to the FR4 laminate and will break off on their own, looking ugly and possibly hanging over the pad you're trying to solder to, leading to assembly problems. Personally I've never heard of anyone with soldermask between pads on standard 0.5mm pitch TQFPs, so I'm not sure why you feel you need them on 0.3mm pitch artwork.

(edit: I've had one person whose opinion I value tell me that he does in fact require soldermask between pads for 0.5mm pitch devices. He's also used soldermask-defined pads for 0.35mm pitch devices, which means that the soldermask is actually covering part of the copper pad. This is different than soldermask between 0.35mm pitch devices. I double-checked and I definitely do not have soldermask between pads of 0.4mm and below, and have found designs I've done both with and without soldermask between pads of 0.5mm pitch devices.)

All PCB houses I've ever used (and I've been doing this for almost 25 years now) will either reject the design or they will silently remove these fine soldermask features. The truth is that they are simply unnecessary if the rest of your process is up to snuff.

Soldermask helps prevent solder bridging. Solder bridging is caused primarily by excessive solder and secondarily by poor alignment. The correct solution for your dilemma is to make sure the apertures on your paste stencil are not placing excessive paste on the pads. This is a tricky thing to get right, but your stencil supplier should be able to help you determine the correct aperture size based on the solderpaste type (lead-free or leaded), thickness of stencil and so on.

A pretty clear indication that you're doing something wrong is when EVERYONE is telling you your gerbers are flawed.

[ataradov]

And just to be clear, I was mostly set off by this:

> Just because it's easy to come talk to me, why make this my problem?

Not only this is not a valid answer from any sorts of technical support, it is also not a proper English.

It does not matter what you think customer needs. Do whatever modifications you need for %99.9 of the orders. But in this case a specific requirement was made, and you agreed to deliver. If you know that you can't manufacture a board like that or just don't want to deal with PITA requirements from a small customer, then simply reject the order as many did before.

A company I once worked for, used openings in the solder mask as mechanical features in a piece of equipment. The requirement obviously was to manufacture them to our spec with no changes, so we had to shop around for manufacturer willing to spend a bit of extra effort aligning things a bit better than usual. The one that agreed, delivered just that, as expected.

[aandrew]

Is English countable?

I'll have three English, please.

[ela_ela]

There's a very good reason for this, and I'm positive that any vendor who rejects your order because of this would have explained it to you.
...All PCB houses I've ever used (and I've been doing this for almost 25 years now) will either reject the design or they will silently remove these fine soldermask features. The truth is that they are simply unnecessary if the rest of your process is up to snuff.

I have no problem if a vendor or PCB house is rejecting my design or my specifications, there are enough others who are accepting and delivering.

A pretty clear indication that you're doing something wrong is when EVERYONE is telling you your gerbers are flawed.

EVERYONE?


eurocircuits


Shenzhen PCB house

[imp]

Hi,
your problem is quite interesting to me. My last boards from hackvana had quite a bunch of problems too. One had a broken off piece of solder mask on one pad (->

) - after reading this thread I wondered, what sizes the aperture my gerbers specified.
Looked at them, they were overlapping on those pads - so it should be one big solid opening in the  mask!
A friend made some high-res shots through his microscope -

.
After removing the pillow distortion with gimp (the new versions with more GEGL support rock) and already ontop of the gerber:

.
Make it 50% transparent:

.
The pads are 1.009x0.6909mm according to the D-code from the gerber (hackvana: D-26).
Now load it up in http://physlets.org/tracker/ , add a calibration stick (blue) and some measure tapes (red) we got:

(high res without the gui:

).

So.... What happened? Did the shrink the aperture? Did they made a new one from the pads in the copper layer? Why did they even touch it and introduce features to the mask, which they cannot produce?! 
Oh, and can someone explain why the copper flooding isn't the same as in the gerbers? The pad in the center is on the same net (gnd) as the flooding, so it's allowed to be there.

tl;dr: Fab shrunk my mask openings and added production problems on their side - see .

Leasons learned, don't order there again. If something goes wrong and hackvana's opinion is "they are not up to spec, but they should work anyways", you'll have a hard time to pin him onto sticking to what he advertises - which he blames on the fab (true, it's their fault, but HE sold the boards to me, not the fab, so if the boards turn out bad, HE should get them remade on a instant and not after several months until the fab might accept they messed it up). I fully agree with ataradov, stick to your spec!

Over the years we had all kind of problems: moved compenent labels in the silkscreen, deleted circles on the silkscreen, boards that failed the E-Test and were in the stack of passed boards, drill tolerance way beyond the +-0.09mm, copper (and or ENIG plated copper) in (routed) holes, slots that looked like they used a chisel....
Between the problems there were also good boards and I was told "you are one of two unlucky guys which gets all the bad boards", but at some point, all the patience comes to an end.

[imp]

Hackvana, can you explain why the fab removed in ela_ela's case the soldermask between the pads and INTRODUCED them in my case?

[T3sl4co1l]

Cheap fabs may not take the time to inspect files as thoroughly as others.  You get what you pay for and caveat emptor.

The person to avoid is Hackvana, that guy is a complete scammer!  Oh wait, it's me.

(special shout out to ataradov: I'm not a low life bastard in China, I'm a westerner in Australia)

There are many things that ela_ela didn't mention in his message, and several things where he's quoted a private conversation in public, and quoted me out of context.  I hope you'll allow me to set the record straight.

[...]

 

Thanks for an assembler side review!

Tim

[imp]

Cheap fabs may not take the time to inspect files as thoroughly as others.  You get what you pay for and caveat emptor.

Hackvana isn't the cheapest option. Choosed him because I thought you can talk to him, but this only holds until you got a real problem. He advertises with explicit values on tolerances and such - something you shouldn't do if you (or your fabs - which is the same from customers point of view) cannot hold these promises. And he's not advertising his PCBs like dirtypcb's does.

Anyway the point here is, they messed around with the files in two different ways.
A) Ela_ela's case: removed stuff they cannot do - but hackvana seemed to agree th provide the boards with exact this feature for a price he picked.
B) My boards: /Added/ features on the soldermask by shrinking the appartures. There were no extra agreements on this one, besides he already knew for old orders, that changing the gerbers will not go unnoticed and produce problems.

A & B have in common: changes were made in the soldermask. His explanation for A doesn't fit on B. So what's going on here? Choosing an answer that fits the current situation?

[mrpackethead]

Just ask for the Fabricator to provide their working gerbers before they produce.