Adhesive instead of solder for surface mount components?
Alexander (Sandy) Hapgood
Posts: 360
Has anybody considered Master Bond EP79FL as a substitute for solder when assembling surface mount components to printed circuit boards?
The spec sheet states it's electrically conductive and gives a number though I'm not sure what that number means.
If this stuff worked it could make surface mount very easy.
Sandy
The spec sheet states it's electrically conductive and gives a number though I'm not sure what that number means.
If this stuff worked it could make surface mount very easy.
Sandy
Comments
One catch I notice is the curing:
To optimize its properties, the recommended cure schedule is overnight at room temperature followed by a heat cure of 2-3 hours at 200°F.
Sounds like a bit of a hassle if you have to do that.
Then I wonder how long you can work with it after mixing the components. You don't want to have it start to set in the middle of mounting a few dozen devices on a board.
Anyway, depending on what surface mount devices you have they can be pretty easy to solder. I was surprised to find that soldering down large size SM caps and resistors can be quicker and less of a chore than through hole. I have not tried it yet but from the various videos and demos I have seen soldering down surface mount chips need not be very hard either.
Until of course the parts get too small or the pin pitch too fine. But then you probably won't be able to do it with epoxy either.
Are you going to try it?
From the looks of things, I think the glue dried out resulting in the ribbon cable coming loose from the PCB. It was very strange.
Base on my experience with the LCD cable, I think there are times manufactures glue parts rather than solder.
I'm pretty sure it's not uncommon for smt parts to be glued to the PCB prior to soldering. This isn't with conducting glue though, it's just to hold the part in place.
Yes, exactly. Back at HP in the early 90's, we placed all passives on the bottom side with a Fuji GL2 Glue Dispenser. An extremely slick machine for it's time, it would precisely place little dots of glue at the centroid of each part's location. The PnP machines would place the parts and reflow would cure the glue. Topside would run with your typical solderpaste and reflow again. The bottomside SMT parts would get soldered when the board ran across the wave solder. This process is still used in a lot of class 1 product (cheap DVD players, stereos, etc), but it's just easier to paste both sides nowadays. Plus, try dispensing a dot of glue between the pads of an 0402, yikes!
First I have to find the adhesive and then I have to find the time. If I do get to it I'll certainly share the results.
Sandy
But having done major repairs on homes, I'd much prefer to deal with pulling nails than trying to separate everything stuck together with glue.
Soldering has been around for thousands of years, and it allows desoldering for rework. Not sure what to do with things that are just stuck together. I tend to stick with the traditional solution that has withstood the test of time until a new innovation proves obviously superior.
For years I visited the dentist to get amalgams and gold inlays. These seemed to always fall out and in some instances requiring removing more tooth for a good mechanical fit. Nowadays, my dentist uses a plastic that is cured by light. Less drilling, longer periods between rework. And my four upper front teeth are capped with titainium oxide ceramic rather than gold with porcelain overlay. In these cases, every new techique was a big win for me. Why should I bother buying gold for teeth at $1200/ounce, only to have the gold mysteriously disappear (not deducted from my bill), when I need a replacement? There is a future in plastics.
I've used the glue to make tiny flexible PCB repairs. Some small assemblies are almost impossible to deal with.
It is possible to succeed at this, but everything has to be considered. And I get the feeling that it would be first deployed in big production runs if their was an increase in yield or a significant lowering of cost. The parameters for changeover are pretty well defined as financial.
Rework is more of an issue to the DIYer. But I also prefer to solder in a well-ventalited area over breathing solvents in the same area. Other than acetone, many solvents directly affect the liver. I still recall a neighbor boy that got into glue sniffing from model airplanes and was never quite right after that.
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My attempt to use epoxy, hot glue, and super-glue have had very mixed and bizzare results. I haven't tried silicone as it goes bad after being opened. The projects are too small to justify the costs.
Just Googled the product and it states that the conductivity is 0.005 Ohm per Centimeter. I can see using this product for mounting SMD's that have a large heat transfer pad such as regulators that are very difficult to properly use without reflow equipment.
Got the following information from a technical representative at MasterBond.
I told the tech rep what I was planning to do and he didn't indicate it was a bad idea. I still have to obtain some EP21TDCS though. The journey continues.
Sandy