I am attaching an SOIC Attiny1634 to an nRF24 without any PCB (to save space). The Attiny is held on (upside down with its legs in the air) with a bit of double-sided sticky - so far so good.
I am using the nRF24 pins as convenient connections for programming - also, so far so good.
But I also need a connection to the reset pin and I want one for the Tx pin (for debugging).
I figured I could make them from small bits of solid copper wire soldered to the relevant pins and glued to the bottom of the chip (for strain relief) with some epoxy. But, to my surprise the epoxy got a very poor grip on the black stuff the chip is encapsulated in and the first time I put any force on it it came off.
I then discovered that the black stuff is so hard I could not scratch it (for extra grip) with a scalpel.
I have just cleaned the black stuff with methylated spirit and epoxied it again.
While waiting for the epoxy to set I wonder if anyone has a better suggestion for glue that will be suitable for this job. It needs to have body similar to epoxy - i.e. thin watery glue will not grip the wires.
UV glue is not good, I done some tests with that glue and it comes out really sticky and the feeling of a
slippery oily cream, it get's "hard" as a silicon for bath it's soft like rubber ball and the UV light is not reaching under surfaces the material needs to be transparent.
Why not use HotGlue? solder a isolated copper wire on the chip and on the other end a pin having it flexible you can hot glue it above any component and hot glue it's not conductive.
Hot glue seems to be perfect. It sticks like hell in the beginning.
I have been using it for years. No not the cheap stuff, but the well known brands.
If you need long time stability, just use super glue (works in most but not all a cases).
Use hot glue and two pieces of wood. Sticks like hell. After one year the parts fall apart when you touch them.
Instead of alcohole to clean surfaces I use acetone instead. It removes grease better then alcohol. However, please never use a nail polish remover. It consists of 80% acetone and oils to refatten the fingernail. You do not want to have fat on the surface you want to put glue on.
If you use super glue, you do not have to buy a "preparer" - it is nothing but 90% acetone.
If you guess, that I dislike hot glue you are wrong. I still use it a lot. Just make sure that the stuff is really hot before you apply it. If half of your hot glue stick comes out of the gun by itsself, it is hot enough. And if you put it on a larger metal surface it will cool off before the glue gets into the pores.
If the surface is very smooth, nothing is better than super glue. If it is not, super glue is like disappointment glue.
Car makers like BMW use more than 20 different glues to keep things together. This seems to make it more complicated. I think, they do have a reason for doing this.
arduinoaleman:
Hot glue seems to be perfect. It sticks like ...
This was an interesting post.
I'm not sure how "Use hot glue and two pieces of wood." is relevant to sticking two small wires to a surface area about 2mm x 4mm without increasing the height beyond the thickness of the wires.
I did not use acetone because I don't have any, but I do have some methylated spirit.
The super-glue that I have is medium viscosity and not thick enough for this job - it would spread too thin.
I have stuff called Evo-Stik "Sticks Like" which seems to stick to everything. But its setting time is too slow (or I am too impatient).
