SMD IC sticked to PCB

[carl1988]

Hi all , today I desoldered an SMD IC, It was sticked to the PCB by two reddish circles underneath it. What are those? Aren't spacer or ...?

 

[maton00]

Epoxy or glue

 

[wrenchone]

Yes, they are glue dots used to hold the devices in place after insertion, before they are soldered. the glue dots are applied as part of the automated pick and place process.

 

[carl1988]

Thanks for fast replying. Should I remove them before soldering a new IC? If so, how?

 

[NareshBrd]

Scrape it off with a sharp knife held at an angle?
Clean the PCB properly later.

It is not harmful to leave in place, I think.

 

[carl1988]

Thank you very much!

 

[Refugee1]

There was a plague batch of that glue at one time.
Clean it off as you will most likely be replacing it manually.

 

[carl1988]

The glue was so tight that I couldn't remove it. I just soldered a new IC over it.

 

[tomchr]

As long as you managed to get the replacement IC flat against the board you're probably OK. If not, I'd remove the IC and shave down the glue with a knife blade.

Adhesives are often used to keep the components in place during double-sided assembly.

Tom

 

[wrenchone]

Some manufacturers are partial to assembling through-hole parts with bottom-side SMDs and running the whole mess through the wave solder machine. In that case, the glue is absolutely needed.

If you want the part to lay flat, remove the glue with an Xacto knife. The blade with a round edge rather than the skinnny trinagle-shaped blade, will likely work better at carving the glue spot off the board.