I am a hobbyist doing some research into the carbon black method for making double sided PTH boards at home. My research so far has mainly been reading the numerous patents and journals on the subject, plus countless hours spent in my lab (an old tin shed) trying different chemistry and processes. I'm at the point where through hole conductivity due to carbon is below 2000 ohms for a single 1.5mm diameter hole. This proved to be sufficient for void free plating in acid copper (200g/l H2SO4, 60g/l CuSO4). What makes carbon process most attractive for me is the low toxicity and costs. From what I understand this is a relatively new area in PCB manufacture (< 12 years) and technical information is difficult to come by. This has been the reason for my own pain staking research. Theory of colloid suspensions and surface interaction is way out of my league, and so its all been a trial and error. If anyone is interested I can post the details of what I've discovered so far. For me, I'd be interested discussing with anyone the details of the carbon dispersion process. There are many questions, such as how long to the dispersions last before carbon particles aggregate and become ineffective ? I've learned that the conditioner is a critical step before the carbon dip, since it is responsible for getting the carbon to stick to the surface. 0.3% (wt) gelatin showed to be very effective for this. What formulations are typical used for conditioners ? regards, Adam Seychell --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------