THP DIY
Well, I've tried with mixed results. I haven't used conductive ink, but rather conductive paint (containing silver) using approximately the same techniques as described on the Think&Tinker website. The conductive paint is sold in many places, to be used for "repairing heated rear windows in cars" or PCB tracks.
My problem was to get the holes copper-plated, not getting the holes conductive.
This was the procedure I used:
1. Cover bare DS PCB (no photoresist) with "solar film" used in cars etc.
2. Drill board with CNC mill.
3. Spread out conductive silver paint, and use a squeege to press it down the holes. Then quickly suck the paint out of the holes from the opposite side of the PCB with a (junk) vacuum cleaner.
4. Remove solar film.
5. Put in copper plating bath.
6. CNC milling of tracks for either side.
7. Optional: Tin electroless plating.
My problems was mainly the plating stuff - holes didn't get properly plated (bubbles?), the edges of the holes were over-plated (sharp egdes sticking out) leaving the board "rough" such that it would not lie down flat afterwards. This made it difficult both to mill the tracks or to dry-film the PCB for chemical etching or applying soldermask.
Onfortunately the conductive paint doesn't handle direct soldering well, so the options of leaving the holes coated with conductive paint is not an option, unless it's a via.
Also, I find the need for speed, precision and cleanliness to be very difficult to satisfy. The more stages that are involved in PCB processing, the easier it is that something goes wrong.
I've calmed down a little nowadays, and only does DS non-THP boards myself, since the board houses are both good and cheap in my opinion. I had to try all the THP stuff myself first (at some cost of at least $2000), just to come to the conclusion that it is messy and difficult.
Also, it seems DIY THP is not encouraged by many manufacturers, there is no such thing as a cheap kit for THP that I know of. The cheapest thing I've found is sold by LPKF but it needs a vacuum table and an oven on top of the "starting kit" that cost approx 600 EUR.
I wish you luck in your plating efforts!
/ eplpwr
Well, I've tried with mixed results. I haven't used conductive ink, but rather conductive paint (containing silver) using approximately the same techniques as described on the Think&Tinker website. The conductive paint is sold in many places, to be used for "repairing heated rear windows in cars" or PCB tracks.
My problem was to get the holes copper-plated, not getting the holes conductive.
This was the procedure I used:
1. Cover bare DS PCB (no photoresist) with "solar film" used in cars etc.
2. Drill board with CNC mill.
3. Spread out conductive silver paint, and use a squeege to press it down the holes. Then quickly suck the paint out of the holes from the opposite side of the PCB with a (junk) vacuum cleaner.
4. Remove solar film.
5. Put in copper plating bath.
6. CNC milling of tracks for either side.
7. Optional: Tin electroless plating.
My problems was mainly the plating stuff - holes didn't get properly plated (bubbles?), the edges of the holes were over-plated (sharp egdes sticking out) leaving the board "rough" such that it would not lie down flat afterwards. This made it difficult both to mill the tracks or to dry-film the PCB for chemical etching or applying soldermask.
Onfortunately the conductive paint doesn't handle direct soldering well, so the options of leaving the holes coated with conductive paint is not an option, unless it's a via.
Also, I find the need for speed, precision and cleanliness to be very difficult to satisfy. The more stages that are involved in PCB processing, the easier it is that something goes wrong.
I've calmed down a little nowadays, and only does DS non-THP boards myself, since the board houses are both good and cheap in my opinion. I had to try all the THP stuff myself first (at some cost of at least $2000), just to come to the conclusion that it is messy and difficult.
Also, it seems DIY THP is not encouraged by many manufacturers, there is no such thing as a cheap kit for THP that I know of. The cheapest thing I've found is sold by LPKF but it needs a vacuum table and an oven on top of the "starting kit" that cost approx 600 EUR.
I wish you luck in your plating efforts!
/ eplpwr
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