<<I would like to read your conclusion and test results on why a tilted rack is not recommended. After I read your conclusions I will give you some input on my experience in working with Toppan, Niigata Prefactuure, Japan and Hitachi Chemical, Shimodate Ibaraki, Japan. >> <<One Japanese process that I am truly impressed with is how the above fab shops focus a majority of the copper plating in electroless (more) and then electrolytic (less) versus the states which are less electroless (time consuming) and more electrolytic.>> <<Thomas John Gulley PCB Project Engineer [log in to unmask]>> Thomas: Two of the tests that I have conducted drove that point home to me: The first included varying degrees of rack agitation in the catalyst bath. It was very clear that more agitation was worse. That is, coverage in the holes by the catalyst wasn't as good (measured by backlight) when the agitation was higher (it was not extreme). The catalyst is known to have a weak physical bond to the surface, via the wetting agent "conditioner" and more agitation will interfere with the adhesion of the catalyst on the hole wall. The second test used a tilted rack versus a standard vertical rack. The pieces processed in the tilted rack had very obvious voids upon inspection after the deposition process. I would like to see the test data that you know of. I think that it would have to be very strong data for me to consider trying again. MB ______________________________ Reply Separator _________________________________ Subject: Re: Electroless plating Author: [log in to unmask] at HALSIC_CCSMTP Date: 11/15/95 8:45 AM That could be a long wish list! Whatever you but, I would want to see processing data on the features that will be included. For instance, I personally wouldn't want to see the tilted racks, due to some testing that I have conducted in the past (DATA!). Remember also, that there are two ways to tilt them: off of vertical (z axis) and off of the y axis. The tilted racks create faster solution movement through the holes which can cause problems (IMHO) with the catalyst deposit step. You definitely want to have vibration on the chemical steps. The key is the copper bath, followed by catalyst and conditioners. Include good rinsing too. Get a control system that allows random process loading using varying cycles. Today's high Tg laminates require special processing in the permanganate desmear (you ARE including desmear in the line, aren't you?). Also, get a top notch electroless copper chemistry supplier and tie them into the loop on equipment selection and specification. The best equipment won't help much unless the chemistry is good. The equipment suppliers should have good processing data these days, but they don't always have it. It is hard choosing who to buy from. You MUST see some similar equipment in operation at other shops and talk to the users & installers before you buy. Matt Byrne Hadco, Owego [log in to unmask] (BTW: Why is it that I can't see who writes messages on this system? I get the impression that other users can see the writers' addresses, even when they don't sign the work (90% of the time). The only address I generally see is "[log in to unmask]" Is it the same for others?) ______________________________ Reply Separator _________________________________ Subject: Electroless plating Author: [log in to unmask] at SMTPLINK-HADCO Date: 11/7/95 1:34 PM My company will be installing a new computer controlled vertical electroless line soon. We believe that we have, with the help of our equipment and chemistry suppliers, configured it to have all the features necessary to acheive small hole coverage ( 7-8 to 1 aspect ratio): tilted racks, vibrators, automatic chemistry replenishment for appropriate tanks. Does anyone have other suggestions for optimizing this process? a "perfect" electroless line wish list? Thanks for any input. Lyle Anderson Lundahl Astro Circuits Logan, Utah 801-753-4700