Author Topic: How to glue PA to FR4?  (Read 802 times)

Offline PekkaNF

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How to glue PA to FR4?
« on: May 04, 2017, 04:20:03 PM »
Trying to fix blue tooth loudspeaker for my wife. Micro USB power connector was shot. I replaced it JST XHP connector, but it has no mechanical fastening. Circuit board had no provision for trough holes - I bent pins to surface mount.

So, how do I glue glass filled nylon to circuit board?

Pekka

Online John Rudd

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Re: How to glue PA to FR4?
« Reply #1 on: May 04, 2017, 04:32:16 PM »
Have you tried cyano? ( superglue...)
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Offline Joules

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Re: How to glue PA to FR4?
« Reply #2 on: May 04, 2017, 04:35:42 PM »
If you can drill a couple of holes either side of the USB, coat in hot glue and get glue through holes to form a natural rivet.   Otherwise, Araldite.
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline PK

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Re: How to glue PA to FR4?
« Reply #3 on: May 04, 2017, 05:23:59 PM »
There are two techniques we use commercially:
1: Hot melt glue.  For a quick fix its hard to beat.  The idea is to use enough that you pot the connector into the case. If you just use it to stick two things together it will eventually fail..  It's good because its viscous enough not to flow into places it shouldn't

2: Neutral cure silicone sealant.  We use cases of the stuff for things like sticking large components down to boards and securing wires. It sticks very well to most things. It'll feel too flexible for the first week, then it will harden up quite a lot...

Offline PekkaNF

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Re: How to glue PA to FR4?
« Reply #4 on: May 05, 2017, 03:30:16 AM »
I have used super glue it's really hit and miss, often it does not work. I use IPA to clean PA, but something with superglue and most epoxies and nylon.....maybe the glue joint is just to rigid for flexible nylon?

Hot glue I have used before and thanks to PK's confirmation I'll have confidence to use it between the connector and the board.

Silicone sealant I haven't used before with nylon....I'll put dabs between the case and connector to make the connector more resistant to bending. If just find one neutral one. I probably have few tubes of polyurethane glues for various purposes, but haven't used silicone for ages.

Thank you
Pekka

Offline PekkaNF

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Re: How to glue PA to FR4?
« Reply #5 on: May 09, 2017, 01:03:56 AM »
There are two techniques we use commercially:
....
2: Neutral cure silicone sealant.  We use cases of the stuff for things like sticking large components down to boards and securing wires. It sticks very well to most things. It'll feel too flexible for the first week, then it will harden up quite a lot...

Local shop has Permatex brand stuff, went into shop, had a look to the self and there were more than ten different products, all of them had nearly same description on the box, none of them said anything from electrikery, I took the clear one:
http://www.permatex.eu/product/clear-rtv-silicone-adhesive-sealant/
it does not say anything on the box and very little on the site....does this "Protects and repairs electrical wiring" means that it is non corrosive?

This blue one is used for engine rebuilding here, but I did not take it....I probably should have, but info on then box was non existent.
http://www.permatex.eu/product/supra-blue-gasket-maker/

On lighter side...when I were in USA local electrician told me to get RTV-silicone, because it is for Radio-TV-use.....I lived in a lie long time  :lol:

Pekka

Offline PK

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Re: How to glue PA to FR4?
« Reply #6 on: May 09, 2017, 01:46:19 AM »
On lighter side...when I were in USA local electrician told me to get RTV-silicone, because it is for Radio-TV-use.....I lived in a lie long time  :lol:
:lol:Classic!

The stuff we use is sold as roof and gutter sealant.  It's also known as neutral cure..

If you smell acetic acid  when you use it then you have the wrong type..

PK

Offline PekkaNF

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Re: How to glue PA to FR4?
« Reply #7 on: May 26, 2017, 11:08:03 AM »
It worked remarkkkably well - while it worked....post mortem showed that pads from PCB had delaminated, although the connector stayed glued. Manybe there was still too much flex.

Anyway it was a learning experience....now I'm very tempted to chuck it to electronics recycle. Might have a fast look if I can locate the alternative USB track or whatever is left of it, but it is really miniscule and looks like goes down to inner layers.

Next time I'll be eiter replacing it with similar connector or make fluing leads to relocate power connector somewhere else.