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