Lamp Module Solid State Relay PC Board

This PC board is designed to fit where the inductor is under the heatsink. Here is what the finished product looks like:


Since the board is mounted against the heatsink a convention board with the solder side on the bottom will short out against the heatsink. So I decided to make a pseudo-surface mount board. The solder side will be on top and the parts are soldered onto copper pads. It is a little harder to do, but can be done.

Here is the copper pattern I used. It is designed to be printed on a 300 DPI laser printer (HP LaserJet). The actual size of the board is 1.33 inches by 0.55 inches.



Here is the placement of the parts on the board. The capacitor in the schematic is not on this board. In trying to save space, the capacitor is mounted on the lamp module board where some parts had been removed. This a top view of the PC board.



Some tips on how I soldered the parts. I think a sharp tip on the soldering iron will help. The first part I soldered was the optoisolator. I put a little solder on the 6 pads on the PC board. Then I bent the leads on the chip at a 90 degree angle outwards where the lead goes from thick to thin. I trimmed the lead so that there are little 1/32" stubs. The chip looked like a bug with six little feet. Carefully, I placed the chip on the little lumps of solder on the pads. I quickly put the tip of the soldering iron on the stub and press down hard. The chip will sink a little as the solder melts. Quickly, I released the soldering iron and blew on the chip to cool it off. Do not get the chip too hot. I repeated this procedure for the other 5 leads of the chip.

Here is kinda what I mean by bending the leads up on the chip. The is an edge-wise view of the chip and the PC board.


Next I soldered little wires to the V- and V+ leads on the board. Since 5-20ma of current is passing through these wires, the wire gauge does not have to be large. I used solid telephone wire, probably 26 AWG.

The 1K serial resistor to pin 1 of the optoisolator is next. Bend the leads down and made little feet on the leads. Trim back so there are 1/32" stubs on the leads. Also, the resistor straddles the V+ and V- leads so it has to stand up on the board a little. I soldered the resistor to the pads just like I did the chip.

The 22 ohm resistor is soldered next.

Here is a close up of the soldering job:


The board is done for now. The alternistor is soldered later to align it when the heatsink is removed and the hole is marked on the heatsink.