Electronics Forum | Fri Jul 07 15:18:45 EDT 2017 | emeto
Tony, I will throw some thoughts here: 1. When we speak about shrink/stretch i start thinking about temperature right away. How do you store PCBs and or Stencils? Is your stencil getting hot or cold in the stencil printer? Are the boards on a room
Electronics Forum | Mon Nov 12 13:04:35 EST 2001 | slthomas
We've got a problem with a fine pitch board that has about .005" registration error at each end (towards the center of the board) when it's printed. Apparently we've got a case of board stretch generated at the fab shop. I still have to do some mea
Electronics Forum | Mon Nov 12 16:14:47 EST 2001 | davef
Yes!!! How can we assemble boards with 20 pitch when we allow 0.008� error to the master art? Excellent question!!! IPC-D-300G has nothing to do with assembler requirements. It is written by and for fabricators, so that they can be comfortable.
Electronics Forum | Wed May 17 14:02:06 EDT 2006 | russ
So, what is the pitch of the part and the pad size, also tell us the thickness of stencil. Russ
Electronics Forum | Wed May 17 13:48:37 EDT 2006 | dwelch123
I'm having trouble printing leads on a fine pitch part. The lead is only .008". I'm using a DEK 265 with metal squeegee and using WS200 multicore solder paste.The stencil is laser cut and polished. I've experimented with different pressures and diffe
Electronics Forum | Thu May 18 09:18:33 EDT 2006 | Chunks
Hi dwelch123, 8 mils seems a bit thick to me. I would normally go 6 or 5 mil for fine pitch such as this. One other area to check is the the snap off. Are you using the slow snap off or just lowering the board right after print? If so you should
Electronics Forum | Thu Jun 16 09:13:46 EDT 2005 | russ
We use a 5 mil for 16mil pitch QFPs, Make sure that the stencil has been polished. Type 3 paste. We have used lead free no-clean, lead no-clean, and water soluble lead pastes for these packages. We set the printer for a slow stroke .7 in/min. wi
Electronics Forum | Thu May 18 11:16:16 EDT 2006 | russ
Go 5 or 6 mil thick with stencil, i am not familiar with that pitch but I would recoomnd a 5mil. Was the thickness in this post before and i missed it? Russ
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 | Thu Jun 16 08:31:15 EDT 2005 | jh0n!
The most part I have the most difficulty with is a 16mil QFN. We found that reducing stencil thickness to 4mil, and reducing aperatures for the IC by 20%, and setting local fiducials to the IC helped immensely. We used to get 75% or more bridged ou
