December 19, 2005 The blast method words good for removing Type UR conformal coating. The main disadvantage is that it is a slow process. The biggest concern is to make sure the machine has built in ESD protection and that you check that it is operating properly prior to each use of the machine. The best way to do this is to measure the actual ESD voltage generated when using the blast spray attachment. Don't count on equipment calibration for this. We had an OEM use the machine that was in calibration (the calibration verified the ESD protection was working) but the machine ESD protection subsequently failed and this failure was transparent to the OEM. Consequently, a number of PWA components were damaged from ESD voltage generated from the blasting process. The blasting process can generate damaging ESD voltage if not properly controlled. ----- Original Message ----- From: Douglas O. Pauls<mailto:[log in to unmask]> To: [log in to unmask]<mailto:[log in to unmask]> Sent: Monday, December 19, 2005 12:15 PM Subject: Re: [TN] senior chemist at HumiSeal Sodium bicarbonate (Crystal Marks #34 powder) works well, but be careful as it can be darned aggressive. You might consider their #25 powder, which is a wheat starch base. A little slower, but does not damage mask or part markings. Doug Pauls "Joseph H. Smith" <agkettle@NETSCAP<mailto:agkettle@NETSCAP> E.NET> To Sent by: TechNet [log in to unmask]<mailto:[log in to unmask]> <[log in to unmask]<mailto:[log in to unmask]>> cc Subject 12/19/2005 10:43 Re: [TN] senior chemist at HumiSeal AM Please respond to TechNet E-Mail Forum <[log in to unmask]<mailto:[log in to unmask]>> ; Please respond to agkettle@NETSCAPE<mailto:agkettle@NETSCAPE> .NET Ramon, I have tried the 'bead blasting' method and I am very impressed with the results. On my application, I still had some issues with removal of the blasting media. Wash could not get all the beads out from under BGA's. I have another source that uses Sodium BiCarbonate as the media. Claims that it water soluable. Company is Crystal Mark in California. Andrew Kettlewell Sr Process Engineer Sypris Electronics Tampa, Fl -----Original Message----- From: Dehoyos, Ramon <[log in to unmask]<mailto:[log in to unmask]>> To: [log in to unmask]<mailto:[log in to unmask]> Sent: Fri, 16 Dec 2005 08:32:27 -0500 Subject: Re: [TN] senior chemist at HumiSeal Hi Joseph: For small areas the best Cutting Media in the market is CCR1000/2000 from CCRCo, recyclable, @ 800.443.2726. Very low static generator ( under 50V ). I would not use any cutting media for the whole board. It would take way too long. It seems that your board coating is too thick or the chemical stripper is too old. Regards, Ramon -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Joseph H. Smith Sent: Wednesday, December 14, 2005 12:59 PM To: [log in to unmask]<mailto:[log in to unmask]> Subject: Re: [TN] senior chemist at HumiSeal We use Humiseal 1A33 coating. Whe have used Humiseal 1063 stripper but without much accomplished. Will take 8- 10 hours before anything happens. This is just unacceptable. Other products have left residue under BGA's or have been corrosive enough to pit solder joints or remove component markings. Some semipastes or gel like products have left residue under leads and so on and so on. So you see that is why I have asked the question. Actually, bead blasting was a mechanically technique that sound promising. Removed the coating quite fast but left blasting media under some components that I could not wash out. Andrew Kettlewell -----Original Message----- From: Edward Mines <[log in to unmask]<mailto:[log in to unmask]>> To: [log in to unmask]<mailto:[log in to unmask]> Sent: Wed, 14 Dec 2005 07:22:02 -0800 (PST) Subject: senior chemist at HumiSeal I was the senior chemist at HumiSeal for 12 years. Different polyurethane conformal coatings require different strippers. Do you know which one you was used? Is it yellow? Be careful which stripper you use. Some of them can attack components. Edward Mines BEChE, MEChE 238 Willard Dr. Hewlett, NY 11557 516 205-6523 Yahoo! Shopping Find Great Deals on Holiday Gifts at Yahoo! Shopping ___________________________________________________ Try the New Netscape Mail Today! 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