adhesive to join PCB

[shashank451180]

i have designed "an aperture coupled microstrip patch antenna" using FR4 material. but for fabrication purpose i need to join two PCBs together. so, i'm looking for the same, the best adhesive to join PCBs with low dielectric constant. please help me out.

 

[KlausST]

Hi,

best adhesive

The "best" is usually determined by your requirements.

The only requirement I see in your post is "low dielectric constant".

Is it independent of
* tape / glue
* thickness
* width
* aging
* price
* availability
* temperature
* your surfaces (low energetic, high energetic..)
* ...

I recommend to go to a good manufacturer for the thing you are looking for and do a search for application notes or selection guides.
Like this: https://www.3m.com/
or this:
Usually they know about the technical specifications of their products ... and they want to sell their products, thus they will support you.

My idea: I assume an adhesive foam tape has low dielectric constant.

Klaus

 

[FvM]

I don't understand the low dielectric constant point. If you join PCBs, the dielectric would be formed by the PCB substrates, a thin adhesive layer won't change it. The adhesive should be chosen according to the substrate material, e.g. epoxy for FR4, microwave substrate may need different adhesive for sufficient bonding.

Alternatively, if you want a defined dielectric layer between the substrates, you probably use a rigid substrate instead of a thick adhesive layer. Or may be foam in some cases. The layer thickness should be well defined, though.

A drawing might explain the problem better.