Is there a product to strengthen surface mount connectors?

[Tipsy]

My laptop has what I believe to be a design fault with the connector between the motherboard and the daughterboard inasmuch that daily use and flexing causes the soldered legs to lift off the pads. Typical symptoms are the laptop will start and run fine from cold but movement/flexing or heating/expansion will cause it to freeze/crash as the legs make intermittentent contact.

I have successfully reflowed the solder on each leg but am concerned they won't last. Is there a known product I can use that can take the strain away from the legs and pads such as an expoxy glue for instance?

 

[audioguru]

Usually circuit boards do not flex so I don't know why you have this mechanical problem. Maybe the manufacturer has had millons of complaints and will fix the design problem. Contact them.

 

[Tipsy]

It is a very common problem and Toshiba were dragged through the courts for similar but they won't re-design what are considered to be obsolete models. Their idea of a "fix" is to replace both mainboards which is no better than my reflow fix IMO.

 

[audioguru]

Poor quality cheap circuit boards use poor quality cheap glue to hold the copper traces on the pcb for only one year.
Then after one year the rice-glue lets go and the circuit board falls to pieces.

Buy a better quality circuit boards made by local people instead.

I got thousands of circuits made by a local shop. The management looked like me and talked like me (I am Anglo-Saxon) so I gave them the contract.
Then I peeked and saw that all the workers were oriental but did the job very well. Little kids, mothers and grandmothers.
Everything was perfect. Maybe I was lucky.

 

[Tipsy]

The tracks haven't lifted.... it's the solder that has "cracked" between the connector legs and the pads. Reflowing the solder has cured the fault (dead laptop) but the original design flaw (weakness) remains, where movement between the connecting boards will stress the solder again. I've seen other boards repaired where some sort of glue has been added over all the legs to hold them more firmly to the board they're soldered to. I'd like to get some of this solder friendly glue if anyone knows what it's called (UK suppplier recommendations welcome).

 

[ericgibbs]

The tracks haven't lifted.... it's the solder that has "cracked" between the connector legs and the pads. Reflowing the solder has cured the fault (dead laptop) but the original design flaw (weakness) remains, where movement between the connecting boards will stress the solder again. I've seen other boards repaired where some sort of glue has been added over all the legs to hold them more firmly to the board they're soldered to. I'd like to get some of this solder friendly glue if anyone knows what it's called (UK suppplier recommendations welcome).

hi T,
If you are very careful use a hot melt glue gun stick.

The best way I found is use the glue stick in one hand and an old solder iron bit in the iron and apply the melt sparingly.
Its commonly used to restrain connectors etc.

 

[mneary]

Lead-free solder isn't as flexible as Pb/Sn solder was. It gets brittle and cracks much more quickly under strain.

I'm afraid we'll just have to get used to it.

 

[Tipsy]

Hi Eric, that might be do-able if I cut very thin slithers of glue stick, due to space restraints and the fact these connectors are literally microscopic. I was hoping there might be a liquid epoxy I could just smear on with a toothpick.

 

[Boncuk]

Hi Tipsy,

this would be my approach for one and (almost) forever.

Use thin aluminum or brass (0.06mm) and bend it to fit snug over the connector. Use watchmaker's screws to fix the enforcement to the PCB material.

(I used that method to hold to two AA-batteries and they haven't come lose within five years.)

If there is no space for screws (because of traces) you might use super glue.

Boncuk

 

[Tipsy]

These are the connectors in question, just to give an idea of shape and scale.

I can't see a surefire way of clamping these but can envisage running a bead of liquid glue over the legs but I'm unsure if the ingredient chemicals are safe to use on PCBs?

 

[Hero999]

Use an epoxy resin such as Araldite around the outside of the connectors?
80808 Araldite Miscellaneous Adhesive Araldite 80808 Rapid Epoxy Adhesive (2 x 15ml tube pack) 80808 - From Lawson HIS - UK

 

[Tipsy]

If it's safe to use and won't cause corrosion, that'll do me, thanks!

 

[ericgibbs]

If it's safe to use and won't cause corrosion, that'll do me, thanks!

hi T,
The only problem in using a permanent fixing method is that if it breaks again, you wont be able to get at it to fix it.

 

[Tipsy]

Hi Eric, that is true but without the added support, it will break again too easily. Hopefully, this is a permanent fix. Not a biggie if it doesn't last.

 

[Hero999]

I have used epoxy resin on PCBs with no problems before.

Eric is right that it's permanent but it shouldn't be too hard to remove. Although it's thermosetting, heating it in a re-flow should weaken it enough for you to be able to scrape it, especially if you heat then apply a suitable solvernt.

 

[creakndale]

Use epoxy to stake just the connector housing to the board (no need to epoxy the contacts to the board). I use Scotch-Weld EC-2216 Gray adhesive.

creakndale

 

[esbo]

I posted a similar thread to this about HDMI connectors I believe frequent plugging and unplugging has caused some nearby tracks/solder joints to crack producing problems. This was on my LED widescreen TV, the symptoms were sparkles on the screen, like fine glitter had been scattered on it.
This might be similar to what you might see if the cable was of too low quality and you were getting digital errors in the signal, I can be pretty sure it was not the
cable because it works fine in less frequently used connectors. It is hard to see what else has caused the problem other than the fact I was plugging and unplugging with
the power on, but I would not expect that to cause the symptoms seen, more likely a failure of the system which did happen yesterday.

Anyway my TV is dead as far as displaying a picture is concerned, it will not respond to the remote (although hard to tell with a black screen) although some
of the buttons bleep when pressed but that might be a locally produced sound.

I'm gonna have to take it back to the shop for a refund, it's less than 4 months old so hopefully they will be willing to give me my money back or and other TV. (touch wood)

 

[BrianG]

Is there a way that the daughter board can be secured better so it doesn't move relative to the main board? I have a feeling that any epoxy/glue that is relatively easy to remove if you need to resolder again won't be strong enough, and something strong enough will make the area unrepairable.

 

[Tipsy]

I decided to go with the epoxy over the legs - it's working well so far and I believe the stresses are caused when the laptop is plugged into a port replicator which I don't use... so fingers crossed.

As for the laptop now being unrepairable should the fault re-occur, it's no loss as I bought it broken and can sell it on to recoup my money. As it stands, I got myself a working laptop for little money.

Thanks for all your suggestions and ideas, you've been a great help.