Electronics Forum | Wed Mar 24 23:12:48 EDT 2021 | grahamcooper22
0.66 area aspect ratio...so for example...if the device is 0.5mm pitch QFP, the pcb pad may be 12 thou wide..make the aperture 9 to 10 thou wide...and reduce it's length by 10 % overall compared to the pcb pad.... Depending on device pitch, select ap
Electronics Forum | Thu Mar 25 23:23:00 EDT 2021 | llawrence
The QFP pitch is 0.5mm. Pad size is 1.475 x 0.3mm, and the new aperture size is 1.32 x 0.22mm. I'm not sure about whether or not it is lasered, but on the newly ordered stencil I selected the polishing option. Looks like the pad width is already 2/3
Electronics Forum | Thu Mar 25 20:50:50 EDT 2021 | stephendo
A couple more things. The PCB. What size are the pads? One time a board shop had difficulty putting masking between the pads of a QFP and the pads suffered as a result. When I told them they didn't have to have masking between the pads, the pads w
Electronics Forum | Thu Mar 25 09:38:36 EDT 2021 | spoiltforchoice
Well everything Graham said with some additional points.. You mention manual printing but very little about your stencil or setup. Everything you have said indicates a very limited budget has been expended, however what you have is an extreme exampl
Electronics Forum | Sat Oct 07 16:31:56 EDT 2000 | Elfego
Tray the electroform stencil.
Electronics Forum | Wed Sep 01 05:23:08 EDT 2010 | leeg
We are having solder bridges on a fine pitch QFP and was wondering whether printing speed directly affects the bridging and is there a typical formula to work out print speed?
Electronics Forum | Wed Apr 05 23:56:02 EDT 2000 | angela
Recently we have serious problem of our 0.5mm pitch QFP solder bridge. I check the viscosity of the Litton Kester paster. It's roumd about 700 is it too low. And do you have god solution about it? thanks alot
Electronics Forum | Thu Jun 16 00:24:29 EDT 2005 | mskler
Hi everybody, Can some body tell me that what stencil thicknes is required for the 16mil QFP. I am getting bridging as well as dry at QFP pins. What type of solder 1. Viscocity 2. mesh size 3. flux contents Should be used for this type
Electronics Forum | Sat Oct 07 11:14:39 EDT 2000 | Aaron
1. It is hard to tell, but your PCB vendor should test the PCB. 2. I think the important thing is the width of the apertures. You should have it laser-cut, and control the width no more than 90% of half pitch. Good luck.
Electronics Forum | Mon Oct 09 19:56:41 EDT 2000 | Dave F
CJ: Arturo and the others make good suggestions. Consider: IPC-7525 Stencil Design Guidelines
