TECHNET Archives

July 2018

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Bob Wettermann <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Bob Wettermann <[log in to unmask]>
Date:
Mon, 9 Jul 2018 09:24:00 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (28 lines)
All:

We have an assignment where we need to, amongst a variety of induced  board
and assembly defects, come up with partially filled PTHs.

The objective is to partially fill a PTH on a multilayered, fairly
thermally massive board and make sure it is filled to approximately 25%,
50% and 75% of the height of the barrel. The PTHs have a 2mm hole diameter
and are 1.57mm in thickness.

We have tried to get this done by blocking a certain portion/depth of the
holes with liquid solder mask and then getting the solder to flow down into
the PTH. Subsequent to this we remove the mask. This has not yielded the
results as the mask does not really get to the right level in the hole. We
tried selectively adding solder via flux-cored wire and by the time there
is wetting all around the component lead,  the hole fills up to too high a
level. Using braid and excavating equipment to remove a small amount from
the completely-filled hole has also proven to be a challenge as it is
difficult to uniformly pull solder from the barrel all across its diameter.

One of our thoughts is to have specialty made solder preform "donuts" and
slide them into the hole.....any other thoughts from the crowd?

Thanks!
-- 
Bob Wettermann
BEST Inc

ATOM RSS1 RSS2