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SAC305 Water Soluble Pastes

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SAC305 Water Soluble Pastes | 31 May, 2007

Looking to qualify a new lead free WS paste. I'd like to know who is happy with what material and why. Reflow consistency and cleanability are critical for us. I have a paste I'm using now that is giving us mixed results (reflow issues).

Any info appreciated.

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SAC305 Water Soluble Pastes | 5 June, 2007

We just tested AMTECH's LF4300 with good results. Excellent reflow/profiling capabilities, good processing. And decent cleaning. I say decent cleaning, because we did run into a small issue.

While using Qualitek's LF paste, we experienced a lot of "sudsing" in de-I wash. With the Amtech paste, this went away. However, we did start running into what looked like some residual material on the boards post processing/post wash. I did some quick research, and it turns out that this paste is formulated as either WS or NC. Ionic testing, apparently, foudn these boards to pass either post-washing, or without washing.

As always, your mileage may vary.

cheers ..rob

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SAC305 Water Soluble Pastes | 5 June, 2007

I, too, have finished qualifying the Amtech paste for a dispensing application. We will be experimenting with the component soldering/stencil printing next. The stuff has proven to provide the best of both the no-clean/low solids and water washable/soluble worlds (It's a real pain to satisfy all the lingo/jargon). The disadvantage of going this route is that Amtech is the only company making a product that performs like this, so, having an alternate vendor is not gonna happen. I have pestered solder co. reps from most of the big guys and they don't have much to say about the LF4300, and they do not admit to any plans to duplicate the chemistry.

I have enjoyed the sales and technical support from Indium and Kester. They both have strong products. I hear AIM is an excellent company as well.

My suggestion = Get engineering samples from AIM, Kester, Indium, Amtech, and Qualitek.---- and see which one you like the most.

If you are shoveling the stuff onto your stencils I would certainly factor in the cost (especially with a rising metals market)

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