Latest project SMD 150WRMS power amplifier using vertical mosfets

[gazzagazza]

Lead free solder is the bane of reliability costing $B in telecom spacecraft failures. Tin over time grows whiskers which eventually touch other parts and short out. It’s a myth that lead free is more reliable. Pb added to tin improves solderability and prevents tin whiskers.

Danger to lead-free electronics: tin whiskers - Technology & science - Science | NBC News

Don’t believe it? Here is a list of confirmed failures from tin whiskers.

Whisker Failures

Nice design NigelWright. I like working with SMt parts. You can get 150w from a pair of IRFPx240?

Your examples are very very old. Most of the world has been lead free for a long time and solder technology has moved a long way.

 

[nigelwright7557]

Hi Nigel busy doing a pcb layout for your amp. I would just like to know if Q5 needs to be in contact with the heatsink ?

Yes the Vbe multiplier transistor should touch the heat sink.

 

[nigelwright7557]

Hi Nigel busy doing a pcb layout for your amp. I would just like to know if Q5 needs to be in contact with the heatsink ?

Might be worth making Q5 through hole so it can rest against the heat sink.

 

[Bruce@bluff]

Thanks Nigel