glue measurement

While I don't understand why, this topic comes-up fairly often on SMTnet. [That the topic recurs indicates there truely is a problem and I'm just too doopy to understand it.] Several things: 1 Check the fine SMTnet Archives. 2 Some glue suppliers know that their customers are driving themselves kookoo trying to figure-out how to do this. So, they sell these little torque screw driver thingies that are set to ratchet at about 80% of the force needed break a properly cured glue connection loose. 3 Just glue a couple [unused, non-functional, extra, test] components on the break-away tab of boards at various points [beginning, middle, end] in the lot. Then use a screw driver, pliers, whatever to bust 'em loose. This of course will require a carefully calibrated elbow and an ear tuned to the music of things breaking. That'll work.

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your glue volume measurement is dictated by your stencil aperture size and thickness when you use stencil printing. Why you need to measure your glue volume deposition? I don't think that this is the right way yet for your undefined problem. What's the problem in your glue process why you come up with the idea of measuring your glue volume ? Get the right aperture size and stencil thickness and way you go!!!!

Dreamy

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Franky,

what method are you using for printing glue? metal stencil or plastic?, and is it on contact or off contact ? and what type of squeegee's are you using? basically give us more infomation.

In term's of measuring height / volume, you can do this with off line equipment, look at the ASC website, we're using their Vision Master to measure height, the algorythm's are not quite right for volume tho' but I do know they're working on it. As far are printers go, I don't think the main ones Dek / MPM and so forth can do it but then I've never tried so I could be wrong.

One thing tho' the reason you want to measure the height / volume, is it for missing / knocked off components ?, if so have you checked your cure profile? John

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Specifications of testing force are not fixed, but (incase of wave soldering) the value should be at least 120-150 % of the force the wave. So for small chip components we assume that the force from the wave on the component is about 3 Newton, this means that the measured force with your torque equipment should be about 3,5 � 4,5 Newton� However, personally I have a little doubt about this. Well let�s say, theoretically it may be right, but to mine opinion this accepted force (the value 120 � 150% x the force the wave) should be measured directly after preheat section. This because measuring force on a fixed-cold-glued chip component, gives a higher value then a heated Circuit board, chip, glue dot.

Well I do not know if it is any kind of help but we measure for chip components on rigged circuit board (FR-4 and CEM) between 20 � 30 Newton. For Flex foils where components are glued with silver epoxy, we measure about 2 - 5 Newton.

And dave, I think that this topic comes-up fairly often on SMTnet simply because the fact that more and more process control is demand, and quality department is very happy with statistics. But it can also be a great help to find a possible cause in finding an answer to questions like: �glued parts falling off in the wave solder machine�, �Adhesion loss on passives over wave�.

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Hello everyone,

Your chief variable here is going to be your epoxy. Different materials react accordingly to various inspection methods but, DEPENDING on your print parameters and material, you may be able to utilize an inline inspection machine. Traditionally, many in line inspection machines have focused specifically on paste inspection. As I understand it, some applications have been reviewed at CyberOptics (www.cyberoptics.com) involving various epoxies. As a CyberOptics representative I would be happy to get you in touch with your local representative or the factory applications team to run a feasibility study.

As for testing, a universal bond tester could be utilized with modular heads to quickly change push/shear forces to address various test ranges on your product. This is common in the component assembly environment (die shear, wire bond, stud pull testing) but you may be able to get appropriate fixturing for your board to utilize this type of equipment for PCB component shear. This will give you a calibrated process and allow for quick changover of test heads. This would be an offline process. Royce Instruments (www.royceinstruments.com)manufactures the system 552 and 580 universal bond testers. As a representative of Royce, I would be happy to assist you in contacting your local representative or applications engineering for a product based feasibility study.

Please feel free to contact me if you have any questions or concerns.

Sean D. 480-829-8170 ext 14

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Look like no way you can measure after glue printing. We have been running glue printing for about 2 years and using the "push test" method for testing the strength of connection of component and board. I don't see any problem. For component ( 0603 & 2012 ), I set at 2-3kg force, 3216 component set at 3-4kg force. For "push test", dont't do it on the same location. For printing setting, I set 2 printing per board.

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Frank, Don't know about point 1 but if they don't fall off I don't worry about it. If they do fall off it's generally because someone has mishandled them before the wave, like shoving them into racks and the like. If they have fallen off and you can't see where the glue deposit was then they weren't there in the first place coz there wasn't any glue. If they ain't there and the glue is, but not deformed then they weren't placed. As to point 2. Print a scrap board - it doesn't even have to be the same type ( same thickness is good though ), cure it without components, and you can measure the height with the little skinny bit at the other end of a set of verniers. This should ease your worried mind about high stand off components. You can even whack a couple of scrap components on by hand and wave them too, doesn't matter if there is no corresponding pads - you just want to know if the ol' glue holds on - yeah? If you don't change the printer setting, as long as you follow normal good printing operations, then you should get the same result each time, no? Some Q.A. people love to make things complicated, be careful you don't make a rod to break your own back. Stick in there!

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