Electronics Forum | Tue Sep 25 14:08:59 EDT 2001 | davef
Oooo, the solder on the pad and PGA ball is flowing during reflow down the via to the secondary side? Why didn�t you say so?? ;-) Why would you expect that gravity and capillary action wouldn�t force solder to flow down the solder plated via to the
Electronics Forum | Fri Mar 26 17:12:17 EST 2004 | ben
I have recently encountered a new pcb design with a very high density of components on either side of the pcb. One of the suggested "fixes" is to use the smt pads as vias i.e. the via will be drilled thorough the centre of the smt pad. My concern i
Electronics Forum | Thu Jan 06 08:03:47 EST 2005 | davef
On solder in vias: It looks like the via are not solder masked well and pick-up solder either: * Solder coating ... OR * During leveling It's possible that the design specifies openings in the solder mask for these via. On solder in the unsupporte
Electronics Forum | Mon Mar 04 17:52:59 EST 2002 | davef
Yes, providing the surface of the via is solderable. * If so, how much paste? => Vias come in various sizes. Boards vary in thickness. So, the amount of paste to fill a via varies. Roughly, you�ll need twice as much paste as the volume of the via
Electronics Forum | Mon Sep 24 18:00:58 EDT 2001 | jagman
Does anyone know the cause(s) of solder flowing through a via to the other side of board during reflow causing solder bumps on opposite side? Is this mainly a design issue or could it be process related? Any help is appreciated.
Electronics Forum | Mon Sep 24 20:33:34 EDT 2001 | davef
Assuming you're seeing this during wave solder, the via acts like a heat pipe conducting 450�F [or whatever] air to your solder balls. Check the fine SMTnet Archives for similar threads and perspective on the direction to take.
Electronics Forum | Mon Sep 24 20:49:59 EDT 2001 | jagman
I'm not seeing this during the wave solder process, rather the REFLOW (convection) process. The board was design with the vias located "in" the land area.
Electronics Forum | Tue Sep 25 12:49:58 EDT 2001 | Hussman
Been there - done that. Makes a mess on that 2nd reflow process- doesn't it!?!?!? This is caused by design. If the open via is located in the land area, it will flow thru the via and cause pumps on the opposite side. You can have your vias filled
Electronics Forum | Mon Jan 11 14:48:44 EST 2010 | davef
SR1000 is commonly used for tenting. Search the fine SMTnet Archives on : tenting Someone gave us this note. We have lost their name. It seems to be good advice. If Liquid Photo Image (LPI) solder mask is required, do not tent via holes. Tenting
Electronics Forum | Fri Aug 16 10:00:03 EDT 2002 | davef
You have a very bad situation. It�s tough for the gas, flux material, er whatever to escape when the BGA is sitting on top of it and the blind via is blocking it from the other side. Obviously the vias should have been: * Placed on the edge of the
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