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sOLDER PASTE NOT COMING OFF SQUEEGEE

Views: 4381

#81168

sOLDER PASTE NOT COMING OFF SQUEEGEE | 5 October, 2018

i HAVE A CUSTOMER WHO IS USING A WATER SOLUBLE LEAD FREE SOLDER PASTE AND IT IS ADHERING TO THE SQUEEGEE. ANY IDEAS HOW TO SOLVE THIS ISSUE WOULD HELP.

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#81169

sOLDER PASTE NOT COMING OFF SQUEEGEE | 5 October, 2018

Paste sticking to squeegee:

* Squeegee is heavily magnetized

* Some pastes stick more than ...

* Plastic squeegees stick more than metal

* Old metal squeegees stick more than new

* Paste needs to be worked

* Paste needs to be at room temperature

* Some flux formulations are very sensitive to humidity

* Need enough paste for thumb sized roll. Too little and it won't fall off.

* Can't have too much paste just enough for a thumb sized roll. Too much and it won't fall off.

* Temperature in your screen printer needs to stable. Paste suppliers say that 1°C change can affect paste viscosity by about 10%.

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#81176

sOLDER PASTE NOT COMING OFF SQUEEGEE | 8 October, 2018

The stuff Dave mentioned are the fundamentals. If the items he listed are satisfactory then you need to start questioning the manufacturer.

From my experience if it wasn't sticking before and now it is, then it is a formulation issue.

Paste sticking to squeegees is becoming more and more a thing of the past.

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#81178

sOLDER PASTE NOT COMING OFF SQUEEGEE | 8 October, 2018

+paste was not stored properly Paste doesn't have enough flux and is more sticky than usual. Could be a lot code related or a purchase order related. I wold order a new jar and try immediately.

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#81187

sOLDER PASTE NOT COMING OFF SQUEEGEE | 10 October, 2018

This problem frequently becomes an issue with lead free solder paste, because it has very different rheology than leaded pastes. While not a 100% of the time, the squegees are very ofen the cause. When the regular blades are used (steel squegees), the aspect of the surface is very rough at the microscopic level, which is why the paste is sticking. I would recommend upgrading to very good quality squegees to be smoother, and the paste doesn't stick, now in ALLPCB, we didn't have this problem

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#81188

sOLDER PASTE NOT COMING OFF SQUEEGEE | 10 October, 2018

I do not agree with that.

Stainless is typically used and it works fine. We run many different paste types, RMA, no clean, WS, PB, Pb Free. No sticking issues.

You can spend the extra money and buy coated blades but it is not necessary for most applications.

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dwl

#81192

sOLDER PASTE NOT COMING OFF SQUEEGEE | 10 October, 2018

davef

The rest of your list looks good, but I'm not buying:

"* Squeegee is heavily magnetized"

Magnetic susceptibility of typical solder alloys isn't very high so even if your squeegee was heavily magnetized I wouldn't think it would effect the paste.

Please correct me if I'm wrong.

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Tom

#81599

sOLDER PASTE NOT COMING OFF SQUEEGEE | 13 December, 2018

This is an old joke of Dave's...

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dwl

#81600

sOLDER PASTE NOT COMING OFF SQUEEGEE | 13 December, 2018

Gotcha. Apparently I'm gullible...

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#81606

sOLDER PASTE NOT COMING OFF SQUEEGEE | 14 December, 2018

High quality coated blades are easier to clean but has zero affect to solder paste sticking.

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