How to fill vias so they are airtight?

[btbass]

Is there a standard way to fill vias so they are airtight?
Or would this have to be a special request?
Any help or suggestions would be wellcome.

 

[House_Cat]

Re: Filling Vias?

There are a couple of ways to fill vias and make them airtight. You should discuss it with your board fab.

One way is to fill the via with silver epoxy. This is one way vias are filled under at BGA with via-in-pad, for example. But it also works for vacuum filling. It can be expensive depending on your fab. For fills to which you will solder, the fab will actually plate over the epoxy fill so that the surface of the board is smooth copper and shows no sign of the hole in the filled via or pad.

Another way to fill the via is cheaper and it works - I've used it many times on high vacuum testing equipment. You can tent the via using solder mask. Some fabs use a technique where they tent over the invividual vias you identify with LPI, then they apply your regular LPI solder mask tent over the first set of fills. This provides a very satisfactory vacuum seal as long as you don't have large via holes (<25mils). This method is very dependent on the experience of the fab. Gorilla Circuits in San Francisco, California, USA, does this sort of fill very well ( **broken link removed** ).

If your vias are small, some fabs can plate the vias closed with copper. Copper fill is the cheapest of the methods, but only works for very small vias. It also depends on the equipment and experience of you fab.

 

[chinta]

Filling Vias?

Hi,

There are few methods of filling. it depends on your requirements also. If you want to protect the via holes you can use secondary filling which will be done after soldermask.

Other one is epoxy plugging. In this case, it can be conductive and non-conductive. for this holes will be plugged with conductive/non-conductive epoxy material and then will go ahead with plating for second time.

 

[flypcb]

Filling Vias?

if some size of drills are all filled, for example, all 8mil or 10mil holes are required to be filled. You only need to note/highlight in the mechanical drawings without any further action on Gerber.

However, if only partial 8mil holes are filled, you need to layout a second layer for these exact filled 8mil holes so that PCB shop engineers can pick them up.

In general, the stuff used to fill is solder mask; in some special cases, customer appoints epoxy to fill whose price is 10 times compared to solder mask

 

[eswar_babu77]

Re: Filling Vias?

There are two types of via filling that is in practice.

1. Conductive via filling.
2. Non-conductive via filling.

 

[asifrehmat]

Filling Vias?

I agree with eswar_babu77

 

[btbass]

Filling Vias?

Thanks for the replies, I know it's down to the makers of the board and what they can do.
Just curious as to whether there is a standard way of doing this.
The target is to get airtight fills to withstand 10psi.