Electronics Forum | Fri Oct 30 10:36:26 EDT 2009 | richie_puthotta
Hi, I see a huge solder mask shift on chip comp pads. This would result in mid-chip solder balls or solder beads. Overall, the solder mask workmanship is not acceptable. Mask is on pad.
Electronics Forum | Fri Oct 20 07:03:46 EDT 2006 | sliebl
I really appreciate the input, guys. Having only had the opportunity to run the Contact machines, I was not aware that many of the other machines use coordinates for locals. Now about those damn, mid-chip solder balls.... oh, that's another topic.
Electronics Forum | Thu Aug 19 05:19:31 EDT 2010 | grahamcooper22
I have seen that moisture in pcbs will cause mid chip solder balls. To discount this, take one pcb from a batch that is giving you solder balls and pass it through you reflow oven with no paste or components on (bare pcb)using your normal reflow prof
Electronics Forum | Sat Jan 15 03:30:25 EST 2000 | Dean
I have reduced solder balling by up to 60 percent by changing the placement height on chip parts. Essentially account for the 6 mills of "Z" height to reduce the "squeezing" effects of the chip impacting the solder bricks. Cheap and easy, especial
Electronics Forum | Thu Mar 28 17:54:57 EST 2002 | slthomas
I realize that this is sort of off-topic, but do you have scads of solder beads (mid-chip solder balls, whatever you like to call them) with that stencil design? If not, would you mind sharing which paste it is that you are using? Email if you like
Electronics Forum | Fri Aug 04 07:44:09 EDT 2006 | aj
Hi, Have you incorporated any Aperture Modifications in your stencil.( i.e. Homebase / 10% reductions). I have a similiar problem here with one of our high volume builds and I am in the process of ordering a new stencil with recommeded aperture red
Electronics Forum | Wed Jul 13 14:56:53 EDT 2005 | jdengler
I read the Cookson/Alpha paper "Optimizing stencil design for Lead-free SMT processing". I interpreted it to mean that if you had a mid chip solder ball (MCSB) problem the "radiused inverted home plate of 20/60/20 style" had the greatest impact on r
Electronics Forum | Fri Jan 21 10:40:15 EST 2000 | Dave Chapman
Having adjusted the profile speed slower and adjusting the temps to the recommended lower levels, amazingly the mid chips have almost disapeared (90%). It appears they have been trying to run a "1 profile fits all" on the ovens for Alpha 737 and UP78
Electronics Forum | Thu Mar 11 03:03:26 EST 2010 | grahamcooper22
Hi , Looking at your photo....can I also see a hole in the middle of the joint on the chip component ? Maybe its not just a problem with th ejoint son diodes ? Did you also get mid chip solder balls on chips? If so, I'd almost guarantee the pcb has t
Electronics Forum | Mon Jan 17 08:09:05 EST 2000 | Mark Anderson
As stated previous, the following elements all have a effect on solder beading. Solder Paste, stencil apertures(reduction of home plate), stencil thickness, printing parameters, placement height, reflow preheat and soaking slope and dwell, manufactur
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