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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Clarissa Ortner

#12363

Solder paste temp Humidity controls | 9 March, 1999

We are starting up an SMT line with a printer and convection oven.... The area we are considering for the printer is totally uncontrolled for humidity, temperature and even cleanliness.

We are working on the filters to keep particulates down, but I am worried about the extremes of temperature(Humidity won't be too bad in SoCal by the ocean but could still be a factor). We are going to be using ESP RMA solderpaste. Where would you recommend I research to find out the recommended facility's controls for this issue. The uncontrolled area varies in temp from 70(winter) to 85(summer). I used to work with pastes in controlled rooms and would often notice problems with temp variences.

Last year AAron posted a similar question but his temperatures were alot tighter and ours seem out of bed to me. Any Ideas? TKS from Clarissa

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justin medernach

#12364

Re: Solder paste temp Humidity controls | 10 March, 1999

| We are starting up an SMT line with a printer and convection oven.... The area we are considering for the printer is totally uncontrolled for humidity, temperature and even cleanliness. | | We are working on the filters to keep particulates down, but I am worried about the extremes of temperature(Humidity won't be too bad in SoCal by the ocean but could still be a factor). We are going to be using ESP RMA solderpaste. Where would you recommend I research to find out the recommended facility's controls for this issue. The uncontrolled area varies in temp from 70(winter) to 85(summer). I used to work with pastes in controlled rooms and would often notice problems with temp variences. | | Last year AAron posted a similar question but his temperatures were alot tighter and ours seem out of bed to me. Any Ideas? TKS from Clarissa | Clarissa, The best place to start is with your paste mfr. Call ESP and find out how succeptible their RMA paste is to the environment. Generally, Water soluble formulas are extremely hydroscopic, no-cleans are environmentally resistive, and RMA is somewhere in between. I've run an RMA process for some time and never really noticed slumping or drying. I'm in New England so I get the extremes as far as temp and RH are concerned. A couple of simple tests will help you out. PRINT a circle of paste on a glass slide or a piece of copper and measure the diameter. Measure at 5 minute intervals for an hour and this will give you an idea of how much your paste will slump. This will be your primary concern. The acid test would be to perform the same test in a hot environment. Turn up the heat in an office, put on a T-shirt, and perform the same test. It's quick and dirty but it will give you an idea of what you're in for.

Regards, Justin

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