Electronics Forum | Thu Dec 26 12:12:55 EST 2013 | igorfo
Dear Friends, I need your help to understand requirements and measurement methods for bow and twist of assembled PCB (PCBA have and SMT and TH components). I already check all posts on the site but didn't found any related to my question answers.
Electronics Forum | Fri Dec 27 16:26:30 EST 2013 | davef
I expect to find the specification and measurement method for the bow & twist of an assembly to be on the assembly drawing. Comments are: * Expecting that an industry committee to write a bow & twist spec for an assembly they know nothing about is n
Electronics Forum | Wed Jun 25 03:49:17 EDT 2003 | M.DAttilio
Hello everyone, my company produce Alumina PCB. Till now we mount ceramic BGA on alumina substrate, but now it's hard to find ceramic components so we'd like to mount plastic BGA on this kind of substrate. Do you know problems about it? Please, if yo
Electronics Forum | Wed Dec 29 14:30:28 EST 1999 | Dan Woodward
I am not sure if I have seen an article comparing solder joint strength Vs pressfit although I am sure this has been researched by literally hundreds of companies before they felt comfortable going to pressfit. I know one of the issues with solder is
Electronics Forum | Tue Sep 18 10:43:59 EDT 2001 | henriksn
Hi, And thanks for the advice. I have tried your method now, and it seems to be working. By visual inspection with a microscope it was almost impossible to tell the differrence between the pcb that had been in the frig and the pcb's that were normal
Electronics Forum | Mon Sep 03 08:56:26 EDT 2001 | henriksn
Hi everyone, I work in a development firm, that has a small prototype department. We have recently invested in a small automatic SMD pick&place machine. When mounting over 100 different components, the machine runs out of feedercapacity, and the res
Electronics Forum | Mon Sep 03 16:51:58 EDT 2001 | edmentzer
We have stored PCB's in the refrigerator twice when our old pick and place died during production. One time the boards were in the frig for two days. I put the boards in a tray and covered the tray with plastic food wrap. We waited about two hours
Electronics Forum | Tue Sep 04 11:09:25 EDT 2001 | blnorman
As the others have stated, moisture is the killer. You have to be sure no moisture is allowed to get to the paste. If it does, you'll get solderballs. I would suggest not using a vacuum. The solvents and other volatile components of the flux will
Electronics Forum | Wed Sep 26 14:58:46 EDT 2001 | bobm
i have stored boards in the refrigerator in side a tray (with a lid) for 2 days and still had them reflow with no problems. i don't know if i would go any longer than that. i would not put any qfp's or any other device that is moisture sensative dev
Electronics Forum | Tue Sep 04 09:12:35 EDT 2001 | caldon
Moisture would be my main concern. Even though components are plastic, they can absorb moisture. Moisture is also detrimental to the the solder itself. The water droplets that are left behind (evaporated even) could cause problems (i.e. chlorides).
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