Glueing PCB's Together

I did a LOT of this when I was in college. We had a lathe that turned out single-sided boards from copper-clad. We used white RTV to glue them together. There was too much movement for a harder adhesive, like Epoxy.

I'm trying to imagine how that worked. I'm thinking you meant *mill*.

It's gotta be mill.. But maybe a PCB could be mounted on a big spinning disk and lathed.

D from BC

My leftover pcb material has no photoresist.. I use presensitized PCB material for my 1206 level SMD work. D from BC

Then just do it - the total would be .064" (or maybe .065, depending on the epoxy), which isn't that far from "normal".

In fact, you should probably cut the thing in half and glue it all at once, then cut of what you need when you need it.

But be sure and distribute the epoxy evenly and roll it out well to make sure you get a good bond all over.

Good Luck! Rich

I don't think you can be McGuyver, unless you use duct tape. :-)

I've made a "PC board" using contact cement, wooden board, and copper (roof) flashing. The "traces" were strips of the flashing, individually glued on. Never tried making a double sided board by gluing two single sided boards together, but I'll bet contact cement would work great.

Ed

I have spray on contact cement... I think I have 3M Spray 90 around here somewhere.. I also have contact cement in a can. Water and solvent base.

The Spray 90 probably won't allow me to position, won't squeeze out and there will be trapped air. Bad...

The liquid contact cement is better but I'm afraid there might be insufficient initial tack to allow full cure which might take a long time. If ever.. But as suggested..I could "pin" the PCB's together by soldering jumpers between boards. This would allow any slow curing adhesive.

However...I do plan on using 2 part epoxy.

The worst adhesive I can think of for this app is Elmers White glue or glue stick glue... :P

I also thought of using double sided carpet tape or glue gun glue. :)

D from BC

...and if you add in some fake vias, you might even let in enough sunlight for some of those UV-cure adhesives. Ha!!

Also, I was desperately trying to figure out how to include the word "Mucilaginous" in this reply, but just couldn't quite get there.

And FYI - We were all out of Duct Tape, so I ended up fixing that Ford pickup with a crusty slice of old garlic bread we found under the seat. (*) That ought to qualify!

(*) That is a true story, though I often embellish it to apply to any project for which one doesn't have all the proper tools and equipment. ..which lately seems to be most of them! -mpm .

I had a PC board with a hole about the size of a quarter burnt away. I used some scrap aluminum to cover the hole, and Bondo to fill the hole. After it cured I straightened out the copper foils and glued them to the Bondo. I drilled new holes, and replaced the bad parts. The board was still in almost daily use several years later.

Next thing you know, they'll be publishing the dielectric properties of Bondo!

No, I mean a lathe. Think about bending the copper-clad into a cylinder and turning it. ;-)

The copper-clad was mounted to one cylinder, the tape-up to the second. The two cylinders are turned together. When white is detected on the drawing a knife is driven into the copper-clad. The sensor and knife mechanisms are mounted to the lathe's screw so the artwork is 2D scanned.

Did some neat artwork with brass sheets and high contrast photos too.

And why don't you just buy dual-layer photosensitized material? Mind you, I'm sure you have a good reason for wanting to paste together two single-layer boards (seeing how obvious the dual-layer solution is); I'm just curious why you want to take that route.

Personally I'm happy to have chucked all that yucky home-etching stuff out of my basement. But of course twenty years ago I couldn't have afforded professionally-made prototypes, especially since my layouts were hand-drawn in black ink on vellum. Occasionally double-sided, too.

robert

I have about $100.00 in useless leftover single clad.

In my app, the bottom layer is mostly ground plane. I might not even have a pattern on that layer..just holes. Thermal reliefs might be nice but I can brute force solder.. I might not need photoresist or etching for the bottom PCB..

Also..the material I have is too floppy @0.032 for my app...Doubling it will make it just right. D from BC

"Michael A. Terrell" wrote in news: snipped-for-privacy@earthlink.net:

At TEK,I used to Dremel out the burned area of PCBs,place cellophane tape over the hole,fill with epoxy,and put it in the drying oven to quicken the cure.Then I would use a grinding burr in the Dremel to level out the top side,and drill for eyelets,repairing the tracks with salvaged copper traces and pads or from a PCB repair kit. I never did one as big as a quarter,though.Maybe 1/2 inch tops.

I used a Hysol optical clear epoxy,608,IIRC.(TEK stocked that epoxy.)

Now I keep a RAKA boat-building epoxy kit handy,plus fumed silica filler to thicken it. you can get glass fiber fillers too.

mpm wrote in news: snipped-for-privacy@k79g2000hse.googlegroups.com:

System Three has a nice inexpensive epoxy sample kit complete with an assortment of fillers like fumed silica,plastic microballoons,wood flour,chopped plastic fibers;the last time I checked,the cost of the kit was $10 US PPD. There's more than enough to do several PCBs. Plus you get the Epoxy Book,a very useful source of info on epoxies.(it's also downloadable)

Get some 1 oz.graduated cups from the drugstore or WalMart to mix up small amounts. They are very handy. Oral syringes are useful for small batches.

If I were doing this, I would tape plastic sheeting to both copper surfaces, to prevent getting any epoxy fingerprints on them, and then paint both with epoxy, stack, weight over disposable surface like newsprint, and let cure. Epoxy oozing out all around would be good, just an indication that no voids were left between the boards. Removing the taped cover would also remove any extra epoxy.

Sounds good, but Bondo was all I could find in 1970. Epoxy wasn't easy find, back then.

Good idea.. I have lots of adhesive vinyl graphics material here that I can put on the copper to keep the epoxy spill over away.. D from BC

Which reminds me... I put my heat sink grease, rosin and silicone in medical syringes. D from BC