Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

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SMT electronics assembly manufacturing forum.


Cap securing...

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#37395

Cap securing... | 28 October, 2005

What are you guys using to secure the larger caps on your PCBs? We have been using RTV forever but need something more rigid for a new product. Thanks in advance

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#37427

Cap securing... | 29 October, 2005

You're correct that Room Temperature Vulcanizing (RTV) adhesive is pretty much a cosmetic when it comes to securing components. Beyond that it contains silicone, which produces unsolderable connections in electronics. Further, many RTV seep acidic acid that can damage connectors. If that's not enough, the chemistry of RTV is highly ionic.

Consider an electical grade two part epoxy. As alternatives, consider: * Hot melt 3M Jetmelt 3748, [recommended previously on SMTnet by Dave G ] * UV adhesive, such as Dymax 621Gel, performs fine as long as you keep the bondline thickness below 0.125" AND you don't apply it in areas that are 100% shadowed from the light.

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Slaine

#37457

Cap securing... | 31 October, 2005

we use a chipbonder from loctite cant remember the name of it.......

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#37458

Cap securing... | 31 October, 2005

Thanks for the suggestions guys. Chipbonder seems like a good idea, we use it other places. Only thing that worries me with that is the price, that stuff isnt exactly cheap...

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#37471

Cap securing... | 31 October, 2005

I would second the hot melt glue method. You do have to teach the importance of "more is not always better" and there will be learning curve, but it's a lot better at securing big clunky electrolytics than RTV. It's also a lot cheaper than chipbonder.

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#37484

Cap securing... | 31 October, 2005

We don't think chip mount adhesives have very good sheer strength. If there's any flex induced during vibration, we doubt them to be a good choice.

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