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 | 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 | 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 | Wed Dec 06 16:48:42 EST 2006 | Mario Scalzo
I would be glad to help you eliminate the solder balling and beading that you are seeing. As this is a fairly common defect, I would like to forward you an Application Note that we have developed that explains the cause and possible solutions. Most
Electronics Forum | Thu Feb 08 12:02:15 EST 2001 | slthomas
After reading the variety of responses, I feel moved to ask if you're you talking about what are occasionally referred to as solder beads (mid-chip solder balls, attached to the waste line of your chip caps and resistors) or the solder balls that ten
Electronics Forum | Fri Jan 14 17:51:37 EST 2000 | Dave F
Dave: Two more things: 1. Let's go backwards, so what changed that suddenly you've realized that "piles of stencils" are causing solder ballig on chips? Are we speeding down the wrong road? Or is this something you lived with and now have decid