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Adhesive for PCB component assembly?

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dalmation

Member
Hello,
I am looking for an adhesive to help me assemble some circuit boards (mostly SMT).

I want to glue all my IC's in place (ideally the smt capacitors/resistors as well), and then solder them all. It will be a lot quicker and neater for me than 'tacking' the corner pins with solder etc.

In an ideal world- the glue should let me 'solder through' in case a little gets on a pad (especially with resistors and capacitors).

To clean off flux, I wash all my boards in an isopropanol (IPA) bath, so again- in an ideal world- it would be great if the adhesive washed off at that stage.

Am I dreaming or does such a product exist?

Thanks in advance for your time.

-DAlmation.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Sounds like a silly idea? - if you're soldering by hand then just tack the corners - if you're wave soldering then the chips are glued down underneath them, by the robot that fits them.
 

jpanhalt

Well-Known Member
Most Helpful Member
For SMTs, you can use a cyanoacrylic adhesive (CA). Most CA's will simply go up in fumes with heat during soldering. If it doesn't, it is not a problem to leave it on the board, under the component after soldering.

The trick is to get a small enough "dot" to hold the component without spreading onto the solder pads. I apply the CA as a small drop to a non-reactive surface. An old piece of PCB works well. You want to avoid any surface that acts like a "base," as in acid/base. Then, I use a piece of steel music wire (0.032 to 0.050 " diameter) to place a very small spot of the adhesive onto the PCB. Add the component, press down, and it will stay. I use thin CA with a set time of about 10 seconds; however, on a non-reactive surface (i.e., the big drop), it will not set-off and get hard for quite awhile. Older CA may be better in that regard than the really fresh stuff. Once you press the component in place, it will harden quite quickly. If you need to change the orientation after the CA gets hard, just heat the component to soldering temperature and the CA will loosen.

All that being said, I find a little paste flux works almost as well and is quicker in most cases, except you sometines have to keep a little pressure on the components to keep them from moving during the soldering process. I use the same wire as used for the CA procedure for that purpose. John
 

dalmation

Member
I wish I did have a robot- its about 00 pcbs that I'm assembing by hand.

I was thinking of CA glue, it is available as a thick liquit and a gel as well.

It will be perfect for the IC's (mostly soic chips), but I'm worried about a mess with the small capacitors etc (thats why I was looking for a soluble glue.

I guess the best thing would be to try it- I didnt think CA would dissapear from pad with soldering, but like I said- I never tried it.

I'll give it a shot and post back- Thanks.

-DAlmation.
 

dalmation

Member
I've seen a website (somewhere) where that was done- but I'm not that bold and daring- I'm just gonna do it all with a hot air reflow station, solder iron, solder braid. Hopefully I can get the help of an adhesive.

I will experiment to see what adhesives I can solder through without making a huge mess. I'll start with some spray mount adhesive that I know washes off with isopropanol, and I'll also try the CA (superglue).

Who knows- I might actually come up with something.

-Dalmation.
 

dalmation

Member
it has components on both sides- I'd still have to glue things down, wouldnt I?

What would be the best way to get the solder to the pads? Would I just get a solderpaste stencil laser cut somewhere?

Something I've always wanted to try- but never really had to make enough boards to warrant it before.

Tell me more.

-Thanks.

-Dal.
 

Sceadwian

Banned
Not with a hot air rework tool. If you're doing components on both sides of the board, you've probably graduated past the point where makeing the boards yourself makes sense, get someone to make them for you, or figure out how to route (using via's or jumpers) all the components to one side of the board.
 

dalmation

Member
I know what your saying, mate- but Its a very component crowded 4 layer board the size of a memory simm- there physically isnt enough room on one side.

The PCB is made for me- but I want to assemble myself.

Its just the initial placement that I want to glue down. I can sit and place loads of components (with glue), then move over to my soldering area (later)and get all the soldering done quickly without having to mess with positioning.

I think I'll need to use CA gel glue for the IC's, then just place the caps/resistors as normal when soldering.

-DAl
 
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