Electronics Forum | Fri Nov 09 10:37:38 EST 2007 | devajj
We have started using QFN packages in large volume and are having problems with no-solders. We are using 6mil stencil with 1x1 paste print to pad. These also have thermal pads with thru vias that we reduce the stencil aperture by 1/4. Board also ha
Electronics Forum | Thu Sep 07 08:45:02 EDT 2017 | dleeper
In my experience with similar sized parts, the nano coatings (or what ever your supplier might call them) do help with repeatable paste release. How are you cleaning your stencils? A big red flag to me is that your stencil worked fine for the first
Electronics Forum | Mon Jul 12 14:30:37 EDT 1999 | Earl Moon
| Hi all , | | We are trying to implement the micro-BGA technology at our plant. I need the clarification to the following points: | | 1. Is underfill required for micro-BGAs? | | 2. What type of stencil apertures are the industry standards for uB
Electronics Forum | Thu Dec 08 10:48:21 EST 2005 | JP
Thanks Russ. As I was writing the post, it crossed my mind that stencil thickness is probably incorrect. I did not question the thickness because it was something that has been discussed with our stencil fabrication shop. When we were ordering mini
Electronics Forum | Thu Oct 21 14:02:32 EDT 1999 | Ron Costa
We are a contract manufacturer currently building a job with IBM CBGA-255 devices and 20mil QFP's that are close to each other. We use a 6 mil laser cut and electro polished stencil with one to one apertures on the BGA's. The customer is experiencing
Electronics Forum | Tue Jul 13 13:51:51 EDT 1999 | Earl Moon
| | | Hi all , | | | | | | We are trying to implement the micro-BGA technology at our plant. I need the clarification to the following points: | | | | | | 1. Is underfill required for micro-BGAs? | | | | | | 2. What type of stencil apertures are t
Electronics Forum | Thu Mar 29 12:05:38 EDT 2007 | cecil
OK, just finished our prototype build. PWB 7.5" x 10" 16 layers smallest pitch 17mil smallest BGA pitch 30mil (round apertures) smallest component 0402 total of 1492 placements 5 mil stencil foil (invar) Had numerous PQFN packages that always gave
Electronics Forum | Thu Jun 28 09:07:51 EDT 2007 | mika
Laser cut 0.13mm stencil thicknes works great for us. BTW, are we talking RoHS solder paste? We do reduce the stencil apertures to 88 % of the pads when we go for the RoHS solder paste. Otherwise we go fo 96% reduction in general with some excemption
Electronics Forum | Mon Feb 21 17:56:44 EST 2005 | davef
You want approximately 5 particles minimum across the smallest aperture. So in the case of a 0.8mm device, we use .017" pads with a round 0.020" aperture on a 6 thou thick stencil foils. Here, 0.020" diameter equals 0.50mm. This gives us 0.50/5=10
Electronics Forum | Thu Dec 15 11:06:05 EST 2005 | Samir Nagaheenanajar
You might wanna try a small reduction in your stencil aperture. For example, for a 30-mil pad go 26-mil square aperture with 8 to 10-mil radius on your corners. Also, look at your designs. Is there enough resist between your pad and ball? Another
