Water soluble paste

I am using a 18 mil and below water soluble solder paste (89.5-25-80). I have never used this type of paste. The PCB has a fine pitch component of which I cannot prevent bridging. The paste coverage on the pad looks like it is slumping. It is not a nice defined brick. I don't know if this is normal. What should it look like after printing ?

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| I am using a 18 mil and below water soluble solder paste (89.5-25-80). I have never used this type of paste. The PCB has a fine pitch component of which I cannot prevent bridging. The paste coverage on the pad looks like it is slumping. It is not a nice defined brick. I don't know if this is normal. What should it look like after printing ? | Hi Scott, 18 mil is well within the capabilities of most all water soluble chemistries on the market. So to answer your question, no it's not normal. You should be able to get well defined bricks and consistant volume with out bridging or shorting. Environment play a huge role in the success or failure of printing Water Sol. pastes. And this summer has been as bad as they get. Humidity is the biggest culprit for slump. Set-up can also go a long way to acceptable results. I would need to speak/e-amil w/ you to discuss the details of the application for accurate diagnostics. Best, Tim

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