How to solder LDMOS to copper.

How to solder LDMOS to copper.

[@mathiasmaidana3713]

Hello my friend, I have some questions. From what I see it looks like thermal paste what you use for soldering or is it silver? Or a combination of both. It seems very responsive and how about the thermal transfer? Does it work well for you until today or did you change your work method? Is the last welded still welded and working? How deep is the central cnc to sink the ldmos? I'm about to start a similar project and what I have the most doubts about is what to use to solder the transistor to the copper with a good thermal coefficient. I will be grateful for your instructions

[@jariojala9816]

yes it works well. I have use soldering paste Sn96,5Ag3Cu0.5. Central CNC is just so deep as 1.6 mm PCB needs set legs to surface (0.5 mm) Thermal transfer is very good to copper...

[@mathiasmaidana3713]

@@jariojala9816 thanks my friend, Note that it preheats the general heat until the paste is melted on the other iron, then it lets the copper reach the temperature and once the fusion is achieved, it is quickly removed. I believe it is to avoid damaging the transistor. Also, as can be seen, it cools naturally to room temperature, which I believe is to avoid damaging the solder. any advice is welcome

[@jariojala9816]

@@mathiasmaidana3713 Look datasheet there are temperature profile for reflow soldering, times and temperatures!

[@rustylimbo]

HI, I am confused. Are you sure the word "SOLDER" is the correct Term? Am I seeing that you are using Heatsink compound and then placing the LDMOS in it, then heating and letting it all settle into the Heatsink compound?

[@jariojala9816]

HI, I am sure, becauce compuond is tin (sn) paste. its used solder SMD components to printed board ;)