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

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SMT electronics assembly manufacturing forum.


Adhesive strength specs

Rich Scheleski

#17030

Adhesive strength specs | 10 December, 1997

Is there a spec for the adhesives used to hold down parts before wave soldering. What size dots are recommended and what is the maximum shear force(1LB?) tested for to ensure good adhesion. Your help is appreciated Rich Scheleski

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Frank Murch

#17032

Re: Adhesive strength specs | 10 December, 1997

There is a direct relationship between adhesive strength and surface area. If you graph this it will be linear. The amount of the adhesive should be about 2/3 the gap between the pads. Pad designs change all over so a true and tried rule does not exist. Adhesion does change in certain adhesives with cure time or temp. This was published in SMT in July or August

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Bob Willis

#17031

Re: Adhesive strength specs | 11 January, 1998

As a basic guide the minimum spec you should look for is 500g you should achieve a force on most chip parts of 800-1000g. Parts are lost on wave soldering due to no material, poor curing, poor surface adhesion and poor handling. Its not the wave soldering operations fault even if you see the parts floating in the pot !!!!! | Is there a spec for the adhesives used to hold down | parts before wave soldering. What size dots are | recommended and what is the maximum shear force(1LB?) | tested for to ensure good adhesion. | Your help is appreciated | Rich Scheleski

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