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Charles Bannister
10/31/05 19:02
Read: 806 times

#103208 - Q&A double sided etching
Responding to: Vignesh Prasad's previous message
Hello Vignesh,

1. How to home-make thru holes? Soldering a pin between top and bottom layer to simulate Plated thru hole? how do you do them?

Ans. I solder a pin between top and bottom. This can be done easily when you first start to build the board. Put a couple of coins under the board to raise it about 1/16 inch from a flat surface. Insert the wires and cut off about 1/16 above the board. Do this for all the feed thru and then solder in mass. Flip the board over and solder the other side making sure coins raise the PCB. Once you get the hang of it you can do a lot in a short period of time.

2. What is the etchant do you use? FeCl2 or Ammonium persulphate?

ans. FeCI2. Can't ship Ammonium persulphate into Hawaii via air.

3. Do you etch both sides simultaneously or single side at a time? Because, I usually etch single side by shaking it within a tray of Ferric Chloride etchant, with the copper side up. If I put upside down the PCB, then the toner gets knocked off and tracks get etched away.
Since double sided boards have toner on both sides, how do you do?

Ans. I etch one side at a time. For the other side I protect it by putting shipping tape over it. Four or five passes gives me (2 inches wide * 4 = 8 inches of protected area. I use a flat file to get rid of the tape rough edges. Very quick and dirty way but extremely good way to protect the other side of PCB. I then make a handle using shipping tape (example tape handle folding ___|___) and put on the top of the board. This allows me to drop/raise the PCB onto/from the top of the acid under control conditions (the PCB floats on the acid). This is an important step.

Once one side is etched I then drill the holes and do the other side. Aligning the pattern to the other side is easy and you can get it to a Nat's ass of being on target if you do it right. Its really simple. Just push pins thru outermost edges (four total) and position over the PCB. Use very little glue (I use a glue stick) on four ends to hold pattern in place. Remove one pin at a time flatting down the pattern. Once done it will stay put with rough treatment.

For tinning I use a solder pot and solder. Any square metal pan will work. I use a propane burner to melt the solder. Takes only about two minutes to go from solid to liquid. Then reduce the flame enough to keep the solder a liquid until I am done. Sand the PCB foil pattern and drop in solder. I use an air hose (hooked up to a small air compressor) to remove any solder blocking holes.


Charles Bannister

List of 25 messages in thread
Toner Transfer PCB's      Rob Vassar      09/26/05 14:03      
   Toner Transfer      Farshid Jafari Harandi      09/26/05 14:20      
      Don't forget      Jon Ledbetter      09/26/05 14:36      
         I used acetone      Rob Vassar      09/26/05 15:05      
         clean copper side      Farshid Jafari Harandi      09/26/05 20:18      
   File Edges of PCB top and bottom.      Charles Bannister      09/27/05 00:33      
      Type of paper used      Ashwin Nayak      10/07/05 10:53      
         PNP BLUE Type thermal paper.      Charles Bannister      10/07/05 12:28      
      Amazing      Vignesh Prasad      10/11/05 08:41      
         Double sided...      Robert Perez      10/11/05 14:34      
         Alignment of Top and Bottom PCB Layers      Charles Bannister      10/11/05 14:35      
            Double sided etching      Vignesh Prasad      10/12/05 11:25      
               Double sided post !      Vignesh Prasad      10/31/05 08:32      
               Q&A double sided etching      Charles Bannister      10/31/05 19:02      
                  Bubble tank        Steve M. Taylor      11/01/05 03:13      
                     Making one with these guidelines      Abhishek Singh      11/01/05 07:43      
                     addendum      Steve M. Taylor      11/01/05 10:16      
                     Like these...      Jon Ledbetter      11/01/05 10:26      
                     Something like this?      Vignesh Prasad      11/01/05 21:46      
                        Yes      Steve M. Taylor      11/02/05 09:41      
                  New methods      Vignesh Prasad      11/01/05 21:49      
         Art Paper      Ashwin Nayak      10/30/05 11:49      
            Blue sheet Vs Photographic paper      Charles Bannister      10/30/05 14:52      
            Timing and Tinning      Vignesh Prasad      10/31/05 08:43      
               Tin your self      Abhishek Singh      10/31/05 21:03      

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