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Dean Fowell
11-26-2012, 7:21 PM
Hi all,

Hope you all had a good thanks giving I am working on a Project I cannot release to much info but what I want to do is use a two part epoxy so I can cover my whole pc do the engraving then put the other pc on top and then it would fuse at the moment I engraved the one pc and applied the glue and place the other pc but some of the glue gets in to my channel that I engraved on the other pc if you can understand me then it will block my channel where


Thanks

Kevin Groenke
11-26-2012, 11:54 PM
epoxy is going to be tough to keep out of the engraved areas, perhaps spray adhesive, contact cement or transfer film applied before the engraving would be more viable.

Rich Harman
11-27-2012, 2:31 AM
Hope you all had a good thanks giving I am working on a Project I cannot release to much info but what I want to do is use a two part epoxy so I can cover my whole pc do the engraving then put the other pc on top and then it would fuse at the moment I engraved the one pc and applied the glue and place the other pc but some of the glue gets in to my channel that I engraved on the other pc if you can understand me then it will block my channel where


I took the liberty of translating, I had a very hard time following what you were trying to say. I apologize if I ****ed it up.


Hope you all had a good Thanksgiving. I am working on a Project. I cannot release too much info but what I want to do is use a two part epoxy so I can cover my whole piece, do the engraving, then put the other piece on top, so that the two pieces would fuse together. At the moment I engraved the one piece and applied the glue then placed the other piece on top but some of the glue gets in to the channels that I engraved on the other piece.

It sounds like you are applying a two part epoxy to the workpiece, engraving through the uncured epoxy into the workpiece, then covering it with another piece with the intention that the two pieces become bonded together. If that is correct, I think it will be nearly impossible to do. I'll be interested to hear of some solutions.

Rich Harman
11-27-2012, 2:33 AM
I apologize if I ****ed it up.

Really? I didn't know that B-O-R-K-E-D was a bad word. I just want to be clear that I did not try to use the F word here.

Dan Hintz
11-27-2012, 7:45 AM
Tough to tell without seeing a picture, but my immediate suggestion would be to engrave a channel around the engraved area of interest... give the extra epoxy somewhere to flow. Also, try controlling your flow of epoxy to a metered amount.

Richard Rumancik
11-27-2012, 2:11 PM
Dean, is there an alternate adhesive that may be more suitable? Perhaps a solvent cement that has very low gap-filling tendency? That way if it did manage to get into the engraved channel it would be less likely to plug it.

You can't really apply epoxy thin enough that it would not squeeze out some way or another. Controlling the epoxy thickness (volume) to any degree seems difficult. Even if you could apply (say) a constant .003" thickness, when you compress it to .001" the excess needs to go somewhere. You could add small shims (.002") in select locations and limit the squeeze to say .001". But I really don't see this as practicable.

Have you investigated PSA tapes as an alternative? Some of the 3M products are very good. If it is a clear acrylic there may be some UV-activated adhesives that could be candidates.

If it is a fluidics application or pneumatic application then the adhesive needs to be selected on the basis of fluid compatibility and performance.

George Carlson
11-27-2012, 3:41 PM
I have no idea of what your really tring to do, but here's a suggestion. When multi-layered PCB's are made, they are made from 2 or more double-sided PCB's, bonded together by a layer(s) of semi-cured FR-4. The semi-cured material is very thin, down to 0.002". When the sandwich is pressed together and heated, curing the semi-cured layer and making a permanent bond between layers. Prehaps you could lightly bond the semi-cured material to one layer, laser it, then apply the second PCB and press the sandwich together. This should give you precise control of channel thickness. The trick will be fing semi-cured material capable of be lasered. (sounds like a chromatograph, I did some reasearch years ago where we did the same thing inside of an IC chip)