OK, it looks like there's some help needed here. There are typically three
ways to soldermask a hole. All three can be done by "most" board shops. All
three can be done by outside services who specialize in soldermask or epoxy
services. To help interpret what one may call "soldermasking" a hole I will
list them below.

TENT. Tenting a hole is putting a cover over the hole "tent" this is
typically done with Dry Film. Why? because you want to cover over the entire
surface without dimpling into the hole. LPI  can not do this. LPI can plug
and sometimes fill but it cannot tent. After dry film (or similar) tent one
usually then coats the entire part with LPI soldermask.

PLUG. Plugging a hole is done by filling the hole with soldermask or an
epoxy. With a plugged hole one would not see light thru the hole but there
may be dimpling on the surface or there may be some voids in the "plug".

FILL. Filling a hole implies to "completely" fill the hole with a soldermask
or an epoxy material. Filling is regularly done with conductive via fill.
When one discusses via in pad technology they are speaking of filling the
hole with conductive epoxy. Filling is also regularly done with specialized
non-conductive epoxies. A filled hole would have no to minimal dimpling on
the surface and would have no or minimal voids in the hole fill material.

I hope this helps.

James Hofer
Director of Operations
Accurate Circuit Engineering
3019 S. Kilson Dr.
Santa Ana Ca. 92707-4202
714-546-2162 work
714-473-6127 cell
[log in to unmask]
----- Original Message -----
From: "Jim Henderson" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, August 27, 2004 12:22 PM
Subject: Re: [TN] tented Via


> Cal,
>
> I know quite a bit of board houses, including us, use spray coaters for
> applying our LPI.  The finished thickness of that is .0008 to .001.  So
> there is very little chance that will plug your via hole.  We have to plug
> via holes as a separate screen printing process. If to plug or tent the vi
as
> is called out on your drawing this is how we would do it.  Good luck.
>
> Jim
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Cal Driscoll
> Sent: Friday, August 27, 2004 1:15 PM
> To: [log in to unmask]
> Subject: [TN] tented Via
>
>
> Hello All-
>
> I am not a board fab person but would like to understand why some LPI
> masking processes can not tent vias (non filled).
>
> We have a board house that can tent vias with no issues. When we went to
> another board house the are unable to tent vias. Both shops are huge and
> have international locations. I would think the technology would be there
to
> do this.
>
> thanks in advance,
> Cal
> www.ctdi.com
>
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