Thanks for the ideas....

Bob Wettermann
BEST Inc
Your BEST source for PCB Rework/Repair, Training and Tools
847-767-5745


> On Jul 9, 2018, at 11:25 AM, Stadem, Richard D <[log in to unmask]> wrote:
> 
> Get some high-temp rubber solid tubing of the diameter of the hole. Cut them to length and insert to the desired depth. Add solder and voila! Serve with cookies and milk.
> 
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Wettermann
> Sent: Monday, July 09, 2018 9:24 AM
> To: [log in to unmask]
> Subject: [TN] Getting a hole partially filled on purpose-Ideas?
> 
> 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