[SOLVED] Soldering of components on single sided PCB using Oven

[expertengr]

Hello, If almost half of the components are soldered on a PCB and the remaining components need to solder and some packages can not be soldered by hand but can be soldered by applying solder paste and heating in oven. Question: Is it OK to apply solder paste to only remaining components ? How would it hurt the solder joints of already soldered components ?

 

[betwixt]

It would depend on the components and board layout. It is more usual to solder parts in the oven first then do final hand placements afterwards.

Brian.

 

[expertengr]

Thanks for reply but what about if almost half of the components are already soldered long ago and the remaining components have to be soldered in oven ?

 

[FvM]

It's normal operation to apply at least two reflow cycles to SMD boards, e.g. all double side SMD populated PCB. Some components are however restricted to one reflow cycle, e.g. some HV electrolytic capacitor series. Problem isn't the quality of previously finished solder joints but the temperature strength of the part.

Selective reflow solder for repair or subsequent placement can be best done with hot air gun, preferably preheating the board.

A problem can be however involved with "long ago" if any moisture sensitive IC packages are placed. The board has to be oven-dried before the chips are heated up to solder temperatures again.