As a bare-board manufacturer, I have supplied peelable masks as a value-add at my last three shops. Degree of cure, and thickness of application is important as subsequent thermal cycles, pre-bakes and reflow/wave cycles increase the degree of cure. Overcure makes removal difficult. Undercure can present packaging issues during shipment and storage of the unpopulated wiring boards. Several of our customers have found it easier to have us perform this operation as we have the both the physical and intellectual processes for selective imaging and application that they do not always possess. There is a need to dial in the application for different assembly operations. Once understood it is fairly easy to consistently meet these various requirements. Ian -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Collins Sent: Thursday, January 04, 2007 9:57 AM To: [log in to unmask] Subject: Re: [TN] Temporary peelable solder masks Similar to Steve, our military stuff always gets cleaned. But I did build some class 3 stuff with no-clean - mainframe equipment (commercial) - with a previous employer. Your bank wants class 3 product and very high reliability, but at least you can count on them to not use a hose to clean it off, and they keep the office air-conditioned. Given that at this employer we do contract manufacturing, the likelihood of convincing all customers to agree to no-clean flux is fairly slim and so it's difficult to justify looking at the qualification work. We also have the issue of supporting build over many years, which often forces buying "end of life" batches of parts - which become more difficult to solder over time, so a fairly active flux is required. If I'm understanding Nigel's question properly, I'd never heard of a PWB manufacturer pre-applying peelable solder mask - it's not something I've ever come across as an option. Does it work well? How does the PWB manufacturer apply it? We use the DIY version, we apply it just before wave soldering. We currently use the peelable stuff, we had used the water soluble but with some production volume increases we were finding it clogged up the filters in the cleaners too quickly. regards, Graham Collins Process Engineer, L-3 Communications Electronic Systems Inc. Halifax (902) 873-2000 ext 6215 >>> [log in to unmask] 01/04/07 10:23AM >>> As a yank, at every place I've worked at over the last 19-years has cleaned everything that's been built (aside from the small amount of no-clean residues from hand soldered components done at the end of the main assembly). Products built range from military hi-rel applications to consumer electronics (but haven't built any high volume stuff like cell phones, that's all gone to China). Our customers just wanted things clean... -Steve Gregory- -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Peter Swanson Sent: Thursday, January 04, 2007 4:43 AM To: [log in to unmask] Subject: Re: [TN] Temporary peelable solder masks Cleaning: My guesstimate is that the UK is 85%+ no-clean after either reflow or wave solder. In the latter case, the liquid fluxes have very low solids content these days (~ 2%), therefore low residue. Cleaning takes place in quite hi-rel applications, or before conformal coating, although not always in that case either. No-clean could even be higher than 85% - maybe we'll run a survey here through the SMART Group to give a better picture. I suspect that the TechNet and similar forums' membership are not typical of the assembly industry as a whole. I think it is skewed towards the hi-rel, more complicated or leading edge end of the industry, where the issues are more complex and the outcomes more critical. Therefore people need more help, are prepared and required to go more in-depth, and cover their behinds with extensive in-house research and evaluations... and use other resources. Hence, I think that the percentage of TechNet members who post-solder clean is higher than the USA market as a whole, or anywhere else. Just an impression. I also suspect that the profile of electronics assembly in the two markets are similar, although the US is larger or course - the UK no longer has any high volume consumer electronics or mobile telephone manufacture. We have also lost all the major EMS companies like Celestica, Flextronics, Solectron, Jabil, etc all of whom used to have big factories here - we have just a few stubs left. We have got a bunch of medium size EMS companies, automotive electronics, quite a lot of defence and military, instrumentation, medical, telecom, et al. Maybe the originator of this thread's company, Dolby, is a good example of what we have - they make professional digital audio products here. Nigel is a buddy, by the way. If you divvy the whole thing up by IPC Class I, II, III - I think the percentages would be about the same here and there. Cleaning, therefore, is not necessarily a class issue! Peter -------------------------------------------------------- Peter Swanson [log in to unmask] INTERTRONICS http://www.intertronics.co.uk Tel: +44 1865 842842 Oxfordshire, England INTERTRONICS is dedicated to providing quality material, consumable and equipment solutions to the high technology, high performance assembly industries, incorporating outstanding levels of technical support and customer service. Read our blog! http://www.intertronics.co.uk/blog/blog.htm -----Original Message----- From: Dehoyos, Ramon [mailto:[log in to unmask]] Sent: 03 January 2007 18:26 To: TechNet E-Mail Forum; Peter Swanson Subject: RE: [TN] Temporary peelable solder masks There is another option, use of Kapton dots of different sizes. They peel off rather easily. Peter, are you saying that after fluxing in the wave solder there is no cleaning either? Or only after reflow? Regards, Ramon -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Peter Swanson Sent: Wednesday, January 03, 2007 11:40 AM To: [log in to unmask] Subject: Re: [TN] Temporary peelable solder masks >>>> If you are washing the board after soldering I believe that this is quite possibly the bigger distinction between the UK (& Europe?) and US pcb assembly profiles. We have little or no water cleaning of fluxes after soldering any more. I think the ratio of SMT to through hole is certainly on a par between the two. Maybe even higher here, certainly not lower. Regards, Peter -------------------------------------------------------- Peter Swanson [log in to unmask] INTERTRONICS http://www.intertronics.co.uk Tel: +44 1865 842842 Oxfordshire, England INTERTRONICS is dedicated to providing quality material, consumable and equipment solutions to the high technology, high performance assembly industries, incorporating outstanding levels of technical support and customer service. Read our blog! http://www.intertronics.co.uk/blog/blog.htm -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Barmuta, Michael Sent: 03 January 2007 16:26 To: [log in to unmask] Subject: Re: [TN] Temporary peelable solder masks Nigel: If you are washing the board after soldering I would recommend using a water soluble mask. We have used the Lackwerke Peters GmbH peelable vinyl mask in the past but have moved away from it. Using water soluble mask eliminates the labor intensity of removing the peelable style mask. Also depending on how the peelable is used, configured, applied and cured it doesn't always come off that easily. This is not aimed at the Peters mask but to peelables in general. We apply the temporary solder mask at the assembly level. Since we wash after soldering, water soluble masking materials are used. They are applied by imaged screen printing, localized liquid dispensing or taping depending on board design and volume of product. Screen printing is the most prevalent approach. I'm not sure why your board fabricator is hesitant to use the peelable unless they are not set up for doing imaged screening. However it's not a big leap from doing permanent mask to doing temporary mask. Perhaps they don't have enough customer requests for this to put in the process. I can understand why the fabricator may be hesitant to apply the water soluble mask. If the boards are nor packaged and/or stored correctly it can start to breakdown and also stick or brick together. Regards Michael Barmuta Staff engineer Fluke Corp. Everett WA 425-446-6076 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Burtt, Nigel Sent: Wednesday, January 03, 2007 7:44 AM To: [log in to unmask] Subject: Re: [TN] Temporary peelable solder masks Peter, I guess in part that is what I am asking. Do US assemblers more commonly use the in-house/DIY approach rather than have the PCBs supplied with the masking pre-applied to a supplied (gerber layer?) pattern. Alternatively I know that some use masking that is removed by a post-wave-solder cleaning process rather than peelable. Just surprised that what our suppliers seem to think is not a big problem to provide as a normal service is apparently not so readily available in USA... Or maybe it just depends who you ask! Cheers Nigel Burtt Production Engineering Manager Dolby Laboratories, Inc. - European HQ Email: mailto:[log in to unmask] Tel: +44 (0)1793 842132 [direct line with voicemail] Fax: +44 (0)1793 842101 -----Original Message----- From: Peter Swanson [mailto:[log in to unmask]] Sent: 03 January 2007 15:37 To: TechNet E-Mail Forum; Burtt, Nigel Subject: RE: [TN] Temporary peelable solder masks Nigel, You rightly draw the distinction between a) the types of temporary masks which are pre-applied by screen printing, usually by the pcb fabricator and b) the temporary masks which are dispensed on by the guys doing the assembly. They are different. Whilst it is obviously desirable to have this job done by your fab guy, as you pointed out, it isn't always straightforward. In particular, I remember a few years back when the process window on the screenable materials wasn't very wide, resulting in problems from under/over cure, removal, etc. Maybe the formulations are more robust today. It is possible to make the "in-house" dispensable types more appealing. Dispensing can be by fairly inexpensive robotics. Curing can be quick by heat or UV. Is this approach an option? Regards, Peter -------------------------------------------------------- Peter Swanson [log in to unmask] INTERTRONICS http://www.intertronics.co.uk Tel: +44 1865 842842 Oxfordshire, England INTERTRONICS is dedicated to providing quality material, consumable and equipment solutions to the high technology, high performance assembly industries, incorporating outstanding levels of technical support and customer service. Read our blog! http://www.intertronics.co.uk/blog/blog.htm -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of N Burtt Sent: 03 January 2007 09:27 To: [log in to unmask] Subject: [TN] Temporary peelable solder masks I'm being told that these are not widely used in USA, the common types used here in the UK (Peters and Electramask) not readily available, and they create packaging and shipping problems... thus US PCB suppliers reluctant to supply PCBs with peelable masking applied. Is this true? Now they are by no means a perfect solution to protecting holes on a PCB during wavesolder, but am not aware of another way of doing so in a no-clean RoHS process if fixturing can't do it. What do US PCB assemblers do if pre- applied peelable masking is really not viable? Other ideas? --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------