1
\$\begingroup\$

I am considering using an adhesive standoff in an assembly, replacing my current setup of brass standoffs with screws. The current assembly is reliable, but the assembly time of adding the standoffs is something I'm looking to reduce.

General thoughts about the reliability of such standoffs? I am looking at this product, in particular: https://www.digikey.com/en/products/detail/essentra-components/LCBSBM-6-01A-RT/392198

I tracked down the MDS on the adhesive, here: https://www.essentracomponents.com/en-us/component/skuAsset?mediaId=103296

My application is consumer electronics, so the unit can be subjected to heat and cold in transit and generally in a stable environment once in service. My concern is that the board in question is in a vertical position, meaning the board hangs on the standoffs (gravity wants to pull the board down) and that over time the adhesive will become unreliable.

I'm a user of the 3M MP line of adhesives, and they are quite reliable, but you need some surface area. Any thoughts on this would be greatly appreciated!

\$\endgroup\$
6
  • \$\begingroup\$ There are push-in plastic board spacers that may be easier to insert than your screw standoffs, and would be more reliable than the adhesive mounts. (but I couldn't find suitable illustrations in a quick search.) \$\endgroup\$
    – Peter Bennett
    Commented Jun 3, 2021 at 3:16
  • \$\begingroup\$ @PeterBennett -- For reasons that are complicated and boring that sort of standoff is not possible since the other side of the board will have no clearance against the surface it is mounted against. The current solution has a countersunk hole on the other side, which allows a standoff to be mounted from underneath. The depth of the sink is very small, probably smaller than any double ended snap in out there. \$\endgroup\$
    – jsinglet
    Commented Jun 3, 2021 at 3:33
  • 1
    \$\begingroup\$ Do a test. Mount it a board upside down with it and put weight on the board. Then wait. Or if you can't wait so long maybe measure with a micrometer then measure again some time later and plot things out. \$\endgroup\$
    – DKNguyen
    Commented Jun 3, 2021 at 5:10
  • 1
    \$\begingroup\$ Are you sure you are actually going to save time? To ensure a proper application of the adhesive you need to clean the board, and use some kind of jig to position the pads correctly. And obviously you are reducing the strength of that connection by several orders of magnitude... These days you can get really nice 3D printent parts cheaply, Those adhesive mounts are not exactly cheap, so you could get a 3D printing mounting part at a comparable cost. (Assuming you order a few thousand or so) \$\endgroup\$
    – Arcatus
    Commented Jun 3, 2021 at 6:28
  • 1
    \$\begingroup\$ Pressure sensitive adhesives can take 8 to 24 hours to reach maximum hold strength after assembly. \$\endgroup\$
    – Transistor
    Commented Jun 3, 2021 at 6:46

1 Answer 1

Reset to default
2
\$\begingroup\$

Glue is not advised for production, you have to prepare the surface properly, make sure the glue was stored properly and is within its expiration date, that is applied properly by the worker, then it has to dry.

It's a lot of unknown and lots of risks.

Why not using solderable standoff that can be SMT placed ?

enter image description here

\$\endgroup\$
3
  • \$\begingroup\$ "Weldable" or "solderable?" The example photo is on a PCB. I'd hope you wouldn't weld things to a PCB. \$\endgroup\$
    – JRE
    Commented Jun 3, 2021 at 8:46
  • \$\begingroup\$ Solderable through the normal SMT & reflow process which is pick and place -> reflow like any other component. @JRE \$\endgroup\$
    – Damien
    Commented Jun 3, 2021 at 9:04
  • \$\begingroup\$ Amazing @Damien -- You echo my concerns and and SMT spacer nails it. The ones from Wurth are $$$ but Sinhoo has them for a pretty good price. Hopefully just as good. \$\endgroup\$
    – jsinglet
    Commented Jun 3, 2021 at 12:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.