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Covering vias by soldermask

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damian_s

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Hi all,

I'm a little bit confused about soldermask layer in artwork generation. Should I make all the vias covered by soldermask or not?

Thanks.
 

vias soldermask

Cover them ..
After all, you don't want to fill vias with solder, do you?

Regards,
IanP
 

soldermask over via

Hi,

If the boards are prototype and its still in development process,then you need to unmask the vias for testing purpose,usually prototypes boards are unmasked since it is in development stage,and remember its not mandatory....


And boards are Masked, when its going for mass production with all the iterations
it has gone through,before product release.

Now its upto you to decide, whether to go for masking/unmasking the via?

Hope this helps you.


Regards

Ramesh
 

solder mask over vias

NOT having your vias covered in mask can bring along some of the following problems through the life of the PCB.

When being wave soldered it can cause molten solder to blow out of the holes, leading to damaged vias, solder splashes & solder balls etc on the board as well as later corrosion.

The vias will tarnish & eventually corrode, depending upon the environment.

They can be shorted together by contact from other surfaces.

They can be used for testing, but using a via for testing can lead to damage to the via and a break in the net.

For final production it is best to cover the vias so when creating the solder resist Gerber file do not include the vias.
 

Re: Soldermask Over Via

I would like to add to above good reasons given by other members.

If doing BGAs or uBGAs you should definitely mask Vias on Topside at least. For test purposes you can leave Vias exposed on Bottom side but for production is not good practice for reasons given by other posters.

I am attaching two pictures of BAD via solder mask design on a BGA. You can clearly see not covering vias can lead to all kind of problems.


Majnoon
 

Re: Soldermask Over Via

Hi,

When the Pcb are in deisgn & developing process ,then the purpose of unmasking the Vias is for testing the Pcbs,before final product release.

As cyberrat says,why one need to go for wave soldering while the PCBS are still in the design process?please explain.

And most of the company usually unmask the via for testing purpose,since they probe it into the via and test the functionality,they can't always have test point for every functional blocks though...?


In the previous mail,regarding the Bga masking on top side,we can also use Via Filler.....


Regards

Ramesh
 

Re: Soldermask Over Via

because my board is already protected with some kind like anti ocsidan layer, i never solder mask the vias. and it's has advantages that if my board is prototype and i need to added more component than i can connect it to vias
 

Re: Soldermask Over Via

For through hole components, u should add the mask for vias on both sides of pcb..

for BGA or uBGA, u should add the mask for vias on top side and open it on bottom side..

for BGA or uBGA, use overall masking on top side..
 

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