I used 20ga wire, need to check the exact size.
Stack the two ends to line up the holes.
Use your flush cutter to grip and drive the wire through both boards.
Cut flush with the top of the board.
Repeat for other seven holes.
Now apply a drop of solder to each connection.
Flip over, retrim the back for any that are sticking too far out.
Solder the back and move on to the next.
I work on a scrap of 2x4 to provide a soft surface the wire can push into without destroying anything.
Use a straight edge on the back edge to line them up straight, or your strips may have a natural zig-zag to them.