Don't overlook that you are removing both the organics in the solder paste and the metal (spheres). You certainly need to shake or blast these off, and you will need to filter down to your particle size on any effluent, in addition to any chemical processing needed. Your concerns over ultrasonics are understandable, but I think demonstrate how perceived industry wisdom can persist beyond its use by date. There have been several studies in this area going back so far I can no longer remember who did them. ICI for sure, but I think the late GEC Hirst Research was also involved. The conclusion was that high frequency 70kHz systems (ie current machines) are OK compared to the then 40KHz, the concern over wire bonds etc was misplaced, save only that a poor quality wire bond might fail on cleaning rather than in service. Hopefully other SMARTIES have a better memory/documentation than me and can cite proper references. Mike ----- Original Message ----- From: "Martin Bourke" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, August 04, 2000 11:55 AM Subject: [TN] Cleaning Of Misprinted Boards > I am trying to source a system to clean misprinted PCB's from an SMT > manufacturing process. The system needs to have the capability to remove > both solder paste and (or) glue. It also needs to be able to cater for a > wide range of double sided PCB's which are already built on one side using a > No-Clean soldering process. > > We are currently using a manual washing process which consists of a soft > brush which has a solvent is pumped through it ( Axarel 2200). The slovent > is circulated through a large filter and re-used. The boards are passed > through an Aqueous wash before going back into production. > > Option 1 - Ultrasonic's > I have some concerns about the use of Ultrasonic's because we assemble a > wide variety of products for various customers ranging from RF devices to > P.C. motherboards and medical devices. I am nervous that the ultrasonic's > may cause damage to some of the components on the PCB of affect the overall > life-span and long term reliability of the product. > Q1. Are these concerns justified ? > Q2. Is there anyone else cleaning side 2 of PCB's which are already built on > side 1 using an ultrasonic system ? > Q3. Have there been any studies carried out on the effects of ultrasonics on > discrete components, IC's, Tantalum Capacitors, Diodes, Transistors or > Co-Axial Resonators ? > > Option 2 - Spray Wash System > I have also been looking at what types of Industrial Spray cleaning systems > are available. Are spray washing systems effective for the removal of solder > paste and glue from via holes and plated through holes ? How successful is > this type of system for cleaning misprinted intrusive reflow PCB's. Most of > these systems use a water based cleaning agent in the washing cycle. This > cleaning agent then needs to be rinsed off the PCB's before the board can be > built through the rest of the process. > Q1. Is anyone out there familiar with this type of system ? > Q2. How is the rinse water treated / filtered before it goes to drain ? > Q3. Are there any problems with the cleaning agent contaminating the water > going to drain ? > > > > Martin Bourke > > ############################################################## > TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c > ############################################################## > To subscribe/unsubscribe, send a message to [log in to unmask] with following text in > the body: > To subscribe: SUBSCRIBE TECHNET <your full name> > To unsubscribe: SIGNOFF TECHNET > ############################################################## > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional > information. > If you need assistance - contact Keach Sasamori at [log in to unmask] or > 847-509-9700 ext.5315 > ############################################################## > ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################