Electronics Forum | Thu May 23 10:18:02 EDT 2019 | emeto
A little hard to tell without knowing your part details and behavior and your PCB design. I have seen part warping so much that will show opens joints on the sides and short in the middle at the same time. Theoretically you should have area ration of
Electronics Forum | Fri Sep 25 16:47:57 EDT 2009 | esoderberg
0.5mm pitch QFP's are typically mixed with large components on all of my boards. I usually use a 6 mil stencil with a minimum aperture width of 10 mils. Normal aperture size is 10 x 50 which causes shorts about 20% of the time. A recent purchase of
Electronics Forum | Wed Jan 25 16:18:12 EST 2012 | wrongway
Your uising 6 mil thick screen on 0603 and sot-23 and you think you need more paste? when i use a 6 mil screen on a sot-23 and 0603 it is almost to much paste. 5 mill does just fine on those parts but if you think you need more paste then don't go t
Electronics Forum | Thu Jun 09 07:02:02 EDT 2005 | ajaydoshi
1. We do have PCB with 0402 component, Micro BGA ( 0.5mm pitch , 0.25 mm pad size ). PCB thickness is 0.8mm. What stencil thickness we should use. PCB size 40 mm X 60 mm 2. We have EKRA E4 , What will be optimum setting for above. Pressure, Scquge s
Electronics Forum | Thu Mar 02 17:46:22 EST 2006 | Chris
Go with no greater than 0.005". Pleanty of paste and minimal shorting issues. 0.004" will even work
Electronics Forum | Sun Sep 27 22:39:55 EDT 2009 | rajeshwara
The same issue i faced 2 yrs before , i sugest 1. Use stencil of 4 mils ( Take care of Aspect Ratio and Area Ratio ). 2. Use Solder Paste of Type 4.5 and Viscosity in between 1100 to 1300. ( Try Solder Paste of Cookson or Alpha metals : OM338 T45-L
Electronics Forum | Fri Jan 27 07:30:54 EST 2012 | scottp
We're in the high rel market and use a lot of 5 mil stencils. They give plenty of paste to meet IPC class 3 and survive over 1000 cycles of -40/+125C thermal cycle testing.
Electronics Forum | Thu Jun 16 18:19:05 EDT 2005 | Jason Fullerton
If the uBGA has aperatures that are 0.25mm square, you need to use a laser cut foil no thicker than 3.75 mils to get an area ratio of 0.67, which is the minimum rule of thumb - that's too thin! Electroform would probably work up to 4.5 mils thick.
Electronics Forum | Mon Jan 23 22:53:31 EST 2012 | davef
= 0.66 aperture opening to the stencil wall has been shown to provide the best transfer efficiency and repeatability of the deposited paste. Values from 0.66 to 0.8 insure a good paste release from the stencil. The biggest impact on area ratio is the
Electronics Forum | Thu Jun 09 13:30:34 EDT 2005 | PWH
I would suggest 7mm thick "Durostone" as a carrier material. Cut lip/pocket for PCB so it is 0.05" thinner than thickness of PCB. Allow 0.010" gap on all sides of PCB. Machine lip to width between 0.050" and 0.100" to support under perimeter sides
