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

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SMT electronics assembly manufacturing forum.

clean process vs non clean process



clean process vs non clean process | 1 April, 2004

We are currently using non clean paste and non clean flux in our manufacturing process. But recently our customer feedback that using a non clean process might cause flux blockage in via hole area and potentially might burn or explode the boards over time since our boards deals with high voltage and current. Is it possible? and where I can get information regarding this topic?

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clean process vs non clean process | 1 April, 2004

How high a voltage?

TV products use hundreds of volts on the vertical and horizonatal sync circuits. Historically, these consumer products were NOT cleaned. For your situation, contact your paste supplier.

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clean process vs non clean process | 2 April, 2004

There is no shortage of reasons to clean your boards. Soldering or reflowing your boards leaves �stuff� on them. This �stuff� is normally corrosive and conductive (some fluxes / pastes are more corrosive / conductive than others). In either case, if you do not desire any residue on your boards, clean them. Military, medical, space, flight, and other boards all require specific levels of cleanliness. In most cases, these levels are only accomplished via cleaning.

Some boards are good candidates for no-clean while others are not. While I am a strong proponent of cleaning, I have never heard of boards �exploding� due to flux-clogged vias.

As discussed many times in this forum, no-clean leaves residue on the boards. In the best situation, the residue is not clearly visible but it is there. It is true that most old TV�s were soldered with a rosin-based flux and not cleaned. In those cases, high voltage was not the concern because the board�s density was not high enough to allow sufficient current leakage to cause a short.

Basically, if your customer is concerned about the boards reliability (or lack thereof) due to a no-clean process, then calm their fears and clean their boards. This will eliminate you as a potential source of blame.

I hope this helps�

Mike Konrad Aqueous Technologies

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clean process vs non clean process | 4 April, 2004

Hi Ken

I'm not so sure about the voltage level but I'm dealing with backplane boards.

Michael, Thanks for the information, I dont mind changing the process but I need to understand why I needed to do do. That is only my concern.

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