On Tue, 20 Feb 2001 10:24:31 -0600, [log in to unmask] wrote: >Ahne, > >1. We run the stencil cleaner at room temperature - maybe colder when >water is changed > >2. we use smartsonic 440-R smt detergent made for the cleaner > >3. We use a standard smartsonic ultrasonic stencil cleaner > >4. Production told me they change the detergent when the boards are not >clean after the cleaning cycle is done. > I am not comfortable with this method. What does everyone recommend >for changing the cleaning solution? > >Tenison Stone > > > > > >"Ahne Oosterhof" <[log in to unmask]> on 02/20/2001 10:06:48 AM > >Please respond to <[log in to unmask]> > >To: "'TechNet E-Mail Forum.'" <[log in to unmask]>, > <[log in to unmask]> >cc: > >Subject: RE: [TN] Stencils with glue releasing > > >Good morning Tenison, >We are in the business of making stencils and have learned a few things >about glue and how well it holds up. >The major reasons why glue may let go: >1) The cleaning temperature is too high. Most glues and epoxies used to >attach stencil plates to the mesh and mesh to the frame is chosen to >release >at temperatures over 140F. I suggest you try to keep your cleaner >temperature below 120F. >2) Using a cleaning solution that attacks glues and epoxies. Several brands >of these materials will dissolve glues, especially when used at high >concentrations. Never use these materials at concentrations higher than >recommended by the manufacturer and try to stay well below them if >possible. >3) Ultrasonic cleaning ( and sometimes high pressure cleaning) may have an >impact on glue attachment and may cause a slow, progressive release of some >glues. >4) Over time and use the solution in your tanks may change drastically due >to the addition of the residues you are removing from the stencils. Keep >track of the contents of the tanks. > >Please give me a call to discuss your specific problem and how you can >resolve it. > >Regards, >Ahne Oosterhof >A-Laser, Inc. >(503)641-9428 > > >-----Original Message----- >From: TechNet [mailto:[log in to unmask]] On Behalf Of >[log in to unmask] >Sent: Tuesday, February 20, 2001 05:35 >To: [log in to unmask] >Subject: [TN] Stencils with glue releasing > >Hi everyone! > >My problem today has to do with stencils for solder paste printing. > >We are having a lot of problems with the glue releasing when we go to use >the stencil. Packing tape will hold through the end of the job. The >temperature is OK and the time in cleaner is acceptable according to the >stencil vendor. > >We have checkout our stencil cleaner and the parameters on the various >printers. > >We have had our stencil cleaner for many years and only had the problem in >the last year.' > >We have had no luck with the problem and the stencil vendor is also >confused. > >Has anyone had this problem before and found a solution? > >Tenison Stone >Telex Communications > >--------------------------------------------------------------------------- - > >----- >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 >--------------------------------------------------------------------------- - > >----- > >--------------------------------------------------------------------------- ------ >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 >--------------------------------------------------------------------------- ------ Dear Tenison, Smart Sonic's 440-R SMT Detergent will last almost indefinately when cleaning solder paste because the chemisty is not consumed during the cleaning process like a saponifier is consumed. However, we recommend the 440-R SMT Detergent be changed every 2 or 3 weeks on a regular schedule. The reason is for preventative maintenance purposes. An ultrasonic bath is a standing pool of water. Just as if you placed a glass of water on your desk and checked it 4 - 5 weeks later, the water would be contaminated. To prevent outside contamination, or when the wash water is used for cleaning other applications such as post solder flux from pallets or oven radiators, the wash water should be changed. Regular maintenance is more practical and less expensive than attempting to titrate the concentration or analyze the solution for contamination. You only have 2.5 gallons of 440-R SMT Detergent invested in the bath at a total cost of approximately $45.00. It is easier and cheaper to just change the wash water and replace it with fresh solution. If you are only cleaning solder paste, you will probably be reluctant to change the wash water after 2 - 3 weeks because it will look just as fresh and be cleaning just as well as when you started. However, remember PM is only $22.50 per week if changed biweekly. As for the release of the adhesive bond, my gress would be someone is allowing the stencil to "soak" in the wash water. The adhesives used to bond the screen to the metal foil and frame are not only heat-sensitive, they are also hygroscopic (absorb moisture). A big advantage of the Smart Sonic Stencil Cleaning Process is that the cleaning time is so short. The stencil is exposed to moisture for only a couple of minutes. If a stencil is allowed to remain in water for long periods of time (more than 10 or 15 minutes is all that is takes sometimes) the adhesive will absorb moisture and swell. When dried, the adhesived bond is weakened and will eventually release. Rules of thumb: 1) Don't expose stencils to wash water or drying air temperatures above 120 degrees F. (49 degrees C.) 2) Don't expose stencils stencils to long wash or rinse cycles and 3) Never allow a stencil to "soak" in any liquid. There is an article on our website by Mr. Richard Clouthier (a stencil manufacturer) "Improving Screen Print Yields", EP&P, July '96. Mr. Clouthier discusses the various factors affecting a stencil's integrity and performance. Go to (www.smartsonic.com) and click on the "Recommended Reading" button. If you should have any other questions, please do not hesitate to contact me. Best regards, Bill Schreiber, President Smart Sonic Corporation E-mail: [log in to unmask] Tel: 1(818) 909-6400 --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------