Electronics Forum | Fri May 31 18:00:55 EDT 2013 | hegemon
With regards to first picture.(Large themal vias) I would attempt to measure the area of the ground pad, less the area of the "drain" holes or Thermal Vias. From that result I would reduce the aperture to account for about 50% coverage of that remai
Electronics Forum | Mon Mar 25 21:50:10 EST 2002 | davef
Some of this was copped from Fred. There are numerous package types that now fall under the rubric of land grid array [LGA]. Land grid devices [ie, Bumped Chip Carrier� [BCC], LGA, Quad Flat-pack No-lead [QFN], MicroLeadFrame�, etc] are essentially
Electronics Forum | Wed Mar 21 16:32:03 EST 2001 | mparker
The root cause is dependant on the type of solder "splash", ball, whatever, that you are seeing post reflow. If it is smears, then cleaning the stencil underside is probably the answer. Are you using automatic wipers? How many print cycles between w
Electronics Forum | Thu Aug 05 10:55:09 EDT 1999 | Wolfgang Busko
| | | | | | Hello, | If you are using no-clean and they are entrapped in the flux it is also IPC accepted but i havent found a customer yet who agrees with that. Im sure you have checked your profile. I had the same problem with chip components but
Electronics Forum | Mon Aug 17 02:50:44 EDT 1998 | Bob Willis
| Have an SRT w/preheat, 18 layer board all copper, 456 BGA needs to be removed and replaced. The manufacturer is Chip Express and during reflow it warps up or down. Causing either opens or shorts on the corners. I was using gel flux with multiple
Electronics Forum | Thu Aug 05 11:51:44 EDT 1999 | Wolfgang Busko
| | | | | | | | | | | | Hello, | | | If you are using no-clean and they are entrapped in the flux it is also IPC accepted but i havent found a customer yet who agrees with that. Im sure you have checked your profile. I had the same problem with chi
Electronics Forum | Tue Sep 04 03:10:35 EDT 2007 | chrispy1963
We've got 2 lead free lines running at present and one leaded. Our lead free pallets and stencils were both leaded before changing over. Just take care to remove any built up flux from the pallets as well as hidden leaded solder deposits prior to r
Electronics Forum | Fri Mar 25 10:50:01 EDT 2011 | grahamcooper22
3 deg / sec) then the flux can slump from the paste and solder is carried with it off the pad and will form balls. Finally, are your pcbs dry ? Pass a bare one through the reflow oven before you print any paste on it, let it cool and then process as
Electronics Forum | Mon Dec 04 08:43:39 EST 2017 | bandjwet
If you are looking to rework (after all of the previous suggestions are taken and tried....you have some solid ones in there). When a device like this is placed and is hard to get to we use the 7721 bumping process using a controlled heat source (no
Electronics Forum | Wed Feb 09 21:37:37 EST 2000 | Dave F
Rob: Someone's out there turning over stones, eh? Roller Tinning, Rolled Solder. In printed circuit fabrication, a surface coating of tin-lead, typically 1-2 microns thick, applied to preserve solderability. Still available from some fabricators
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