Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Solder printing issues

zolasteven

#22331

Solder printing issues | 8 November, 2002

Can anyone advise on the following :

1. Insufficient pcboard support during printing

We are printing on double sided pc boards (approx. 8 ins by 6 ins). There is a problem of high paste when we are printing the second side. The reason bsing the board is very dense and and the components are closed together on the first side and we do not have enough support from the nest plate and thus warping the baord during the printing operation. The board is held onto the nest plate by vacuun suction We have trying using support pins but there are locations where there are no room for this pins.

2. Cold solder joint. What are the main causes of cold joint? How can this issue be solved? How do you differentiate a cold joint?

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Jon Fox

#22339

Solder printing issues | 8 November, 2002

1. Back in the early days of consumer digital cell phones, we ran into the same problem. PCB with 2000 parts in a 5"x2" area, and double sided. We ended up using our standard vacuum tooling for the NIC side and stiff ESD safe foam for the NAC side. Took us some time to figure it out, but once we did, it was like magic. 2. A cold solder joint does not wet properly and the joint will have a dull grey porous look. It can come from bad solder (old or mixed), dirty PCBs, or lack of proper heat to reflow the board. Do you have a way to track your reflow process for this board? A small investment in a reflow data tracker can save you time and money by avoiding the rework required to fix the boards or the loss of damaged boards due to too much heat.

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#22346

Solder printing issues | 8 November, 2002

On the board support issue: DEK and Ovation Products make board support things to get at the issue you describe. Ovation hosted an On-Board Forum on SMTnet a while ago.

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iman

#22393

Solder printing issues | 13 November, 2002

we changed our top/bottom clamping system in the Printer, to a side-edge clamping system. This removed the higher paste issue similar to your thread.

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mark

#22499

Solder printing issues | 23 November, 2002

There is some superb tooling offered by a company called Transiton Automation, http://www.board-lok.com. There are some different choices, full molded tooing ... a service,... and re-usable fine grid pin array tooling.

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