[PEDA] Board warpage?
This email is not a Protel-specific question but instead concerns a generic problem with some boards I'm getting, so I apologize for being off-topic, but this forum has more PCB experience than any other I know of, so I would like to get your advice. A partner in a manufacturing effort is sending us full populated boards (ICs and passive components) that are badly warped. We sent them back and rather than get the boards remade and repopulate them, they want to heat the boards up (fully populated) for three days at 150 degrees Fahrenheit in order to straighten them out. These boards perform an extremely important job and I'm worried about the stress on both the electrical components and the boards themselves. Should I allow them to do this or should I demand the boards be remade? Thank you, Michael Robison * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Board warpage?
In a message dated 2004-07-20 11:46:57 AM Eastern Daylight Time, [EMAIL PROTECTED] writes: A partner in a manufacturing effort is sending us full populated boards (ICs and passive components) that are badly warped. We sent them back and rather than get the boards remade and repopulate them, they want to heat the boards up (fully populated) for three days at 150 degrees Fahrenheit in order to straighten them out. These boards perform an extremely important job and I'm worried about the stress on both the electrical components and the boards themselves. Should I allow them to do this or should I demand the boards be remade? My answer would be, It depends. 150F is 65C, and most commercial spec electronics components are rated to operate up to 70C, and often rated to survive even hotter when unpowered. If all they want to do is let them sit on a flat surface at 150F for three days, and you've got a reliable test procedure for the boards before they go into a higher-level assembly, and you can spare the extra three days, I'd say quietly thank them for the extra burn-in. If they plan to apply some force to encourage the boards toward flatness, I'd be a lot more concerned, particularly given that trying to bend the boards with the solder already solidified will place some fairly large stresses on component leads, and at that temperature the plastic cases will be somewhat more yielding - possibly transferring the stresses to the internal bond wires. You might get some internal opens that way, but what would really worry me would be the possibily of getting an almost open, that would later fail under normal usage vibration. There would be a lot of other factors involved, like the potential cost of later field failures, product liability, your future relationship with this manufacturing partner, etc., that only you could evaluate. Steve Hendrix * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Board warpage?
you'll probably get a lot of different answers 150 deg F is not very hot, and this will probably help but still there will be stresses ... since this bd is doing 'a very important job' you may want to tread lightly what is the measure of 'badly warped' ? how big is the board and what is the shape? ie long and narrow or what how many layers ? balanced construction internally? parts on both sides ? what is the cause of the warping? it could be in the design, bare bd fab, or assy method or some combination of all was the board wave soldered at some step? if not preheated properly and that can be one cause keep us posted or put up a link to a pic if you can Dennis Saputelli Robison Michael R CNIN wrote: This email is not a Protel-specific question but instead concerns a generic problem with some boards I'm getting, so I apologize for being off-topic, but this forum has more PCB experience than any other I know of, so I would like to get your advice. A partner in a manufacturing effort is sending us full populated boards (ICs and passive components) that are badly warped. We sent them back and rather than get the boards remade and repopulate them, they want to heat the boards up (fully populated) for three days at 150 degrees Fahrenheit in order to straighten them out. These boards perform an extremely important job and I'm worried about the stress on both the electrical components and the boards themselves. Should I allow them to do this or should I demand the boards be remade? Thank you, Michael Robison -- ___ Integrated Controls, Inc. Tel: 415-647-0480 EXT 107 2851 21st StreetFax: 415-647-3003 San Francisco, CA 94110 www.integratedcontrolsinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Board warpage?
Further to Steve's point on mechanical stresses on the components... The feasibility of the suggestion from your assembly house may depend on where in the process the boards warped. If the bare board was warped when the solder solidified on the components, then straightening the boards without reflowing the solder will place the components under stress. This will be the case even if no external force is applied to the board (ie, even if they are just soaked on a flat surface at 150F). If the bare boards warped as they cooled after reflow/wave, then it is likely that the solder solidified before the boards warped, causing the components to be under stress as we speak. If this is the case (unlikely), then straightening the boards would actually releive the stress. I haven't been in this business long enough to know how hard on components it would be to reflow them a second time. From a mechanical perspective, the best solution would be to reflow the solder, straighten the boards while the solder is still molten and then hold it straight till the boards cool. You might still need to go through a soak period at 150F before the boards would stay straight. Of coarse, running the components through an oven twice could do much more harm than good, not to mention the difficulty in straightening a board at 400 degrees. As Dennis suggested, be careful. Almost anything you do to these boards will shorten their life. Its just a question of how much, and what is the risk if they fail. Darcy Davis Design Engineer, Dynastream Innovations, Inc. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: July 20, 2004 9:55 AM To: [EMAIL PROTECTED] Subject: Re: [PEDA] Board warpage? In a message dated 2004-07-20 11:46:57 AM Eastern Daylight Time, [EMAIL PROTECTED] writes: A partner in a manufacturing effort is sending us full populated boards (ICs and passive components) that are badly warped. We sent them back and rather than get the boards remade and repopulate them, they want to heat the boards up (fully populated) for three days at 150 degrees Fahrenheit in order to straighten them out. These boards perform an extremely important job and I'm worried about the stress on both the electrical components and the boards themselves. Should I allow them to do this or should I demand the boards be remade? My answer would be, It depends. 150F is 65C, and most commercial spec electronics components are rated to operate up to 70C, and often rated to survive even hotter when unpowered. If all they want to do is let them sit on a flat surface at 150F for three days, and you've got a reliable test procedure for the boards before they go into a higher-level assembly, and you can spare the extra three days, I'd say quietly thank them for the extra burn-in. If they plan to apply some force to encourage the boards toward flatness, I'd be a lot more concerned, particularly given that trying to bend the boards with the solder already solidified will place some fairly large stresses on component leads, and at that temperature the plastic cases will be somewhat more yielding - possibly transferring the stresses to the internal bond wires. You might get some internal opens that way, but what would really worry me would be the possibily of getting an almost open, that would later fail under normal usage vibration. There would be a lot of other factors involved, like the potential cost of later field failures, product liability, your future relationship with this manufacturing partner, etc., that only you could evaluate. Steve Hendrix * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Board warpage?
The important sentence below is These boards perform an extremely important job... My vote would be to have the boards remade, and to ensure that the unpopulated boards pass inspection before population. With respect to the existing boards - I'm skeptical that they can be stress relieved at 150deg F. It appears that whomever recommended the procedure is hoping for some creep in the resin over time to fix the problem. You don't mention whether or not the boards are FR4; however, if they are, the temperature suggested is about half of the lowest FR4 Tg normally found in service (120deg C). It is unlikely that any significant creep will occur so far below the glass transition temperature. Even if the boards themselves can be relieved (which I doubt), the components - and the pads to which they are soldered, will be under stress if the board shape is changed after the components have been mounted. Premature failure is almost certain as a result of component and/or joint stress fractures. The cause of the board distortion should be examined carefully. Some common causes are asymmetric stackup, improper lamination cooldown, improper reflow or wave soldering heating/cooling programs, and mechanical stress when mounting large or heavy components. Any one of the above, or a combination, can cause the board to warp because of internal stresses. A properly designed, properly laminated, and properly handled board doesn't warp. At 08:40 AM 7/20/04, you wrote: This email is not a Protel-specific question but instead concerns a generic problem with some boards I'm getting, so I apologize for being off-topic, but this forum has more PCB experience than any other I know of, so I would like to get your advice. A partner in a manufacturing effort is sending us full populated boards (ICs and passive components) that are badly warped. We sent them back and rather than get the boards remade and repopulate them, they want to heat the boards up (fully populated) for three days at 150 degrees Fahrenheit in order to straighten them out. These boards perform an extremely important job and I'm worried about the stress on both the electrical components and the boards themselves. Should I allow them to do this or should I demand the boards be remade? Thank you, Michael Robison snip * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Board warpage?
I would have to agree with the previous posts that are skeptical of success with straightening at 150deg F. We typically use FR4 boards here for characterizing semiconductors at 150deg C. It's not recommended but it's a reasonably inexpensive way for us to accomplish our tasks using prototype PCB technology. The boards will change shape at that temperature if mechanical stress occurs and we do occasionally experience board failures, but not very often. Dan Enslen The only reason time exists is so everything doesn't happen all at once. -Original Message- From: Harry Selfridge [mailto:[EMAIL PROTECTED] Sent: Tuesday, July 20, 2004 9:56 AM To: Protel EDA Forum Subject: Re: [PEDA] Board warpage? The important sentence below is These boards perform an extremely important job... My vote would be to have the boards remade, and to ensure that the unpopulated boards pass inspection before population. With respect to the existing boards - I'm skeptical that they can be stress relieved at 150deg F. It appears that whomever recommended the procedure is hoping for some creep in the resin over time to fix the problem. You don't mention whether or not the boards are FR4; however, if they are, the temperature suggested is about half of the lowest FR4 Tg normally found in service (120deg C). It is unlikely that any significant creep will occur so far below the glass transition temperature. Even if the boards themselves can be relieved (which I doubt), the components - and the pads to which they are soldered, will be under stress if the board shape is changed after the components have been mounted. Premature failure is almost certain as a result of component and/or joint stress fractures. The cause of the board distortion should be examined carefully. Some common causes are asymmetric stackup, improper lamination cooldown, improper reflow or wave soldering heating/cooling programs, and mechanical stress when mounting large or heavy components. Any one of the above, or a combination, can cause the board to warp because of internal stresses. A properly designed, properly laminated, and properly handled board doesn't warp. At 08:40 AM 7/20/04, you wrote: This email is not a Protel-specific question but instead concerns a generic problem with some boards I'm getting, so I apologize for being off-topic, but this forum has more PCB experience than any other I know of, so I would like to get your advice. A partner in a manufacturing effort is sending us full populated boards (ICs and passive components) that are badly warped. We sent them back and rather than get the boards remade and repopulate them, they want to heat the boards up (fully populated) for three days at 150 degrees Fahrenheit in order to straighten them out. These boards perform an extremely important job and I'm worried about the stress on both the electrical components and the boards themselves. Should I allow them to do this or should I demand the boards be remade? Thank you, Michael Robison snip * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Exporting to pdf or Orcad or PSpice
Tis truly easy to print direct to a pdf from almost any application, including Protel EDA. Adobe Acrobat and a large number of third party PDF printer drivers are available. While Adobe's ~$200 package might be a bit overkill for most of us, the third party solutions range in price from around ten bucks to $40... A simple search on DejaNews (google) or at tucows (or similar) for pdf writer will turn up enough to allow you to trial and buy... I've been printing pdfs by selecting a pdf writer as the print device (ie, transparent and simple) for nearly a decade. aj -Original Message- From: Jon Elson [mailto:[EMAIL PROTECTED] Sent: Monday, July 19, 2004 2:01 PM To: Protel EDA Forum Subject: Re: [PEDA] Exporting to pdf or Orcad or PSpice Trent Bates wrote: I am trying to export one of my schematics to a customer. I am using Protel 99SE SP6. The customer would like it in a pdf format or an Orcad format (.DSN file or something of the sort) or something they could read from PSpice. I tried saving one of my schematics as an Orcad .sch file but strange things happened and components went all over the place. What is the best way to export the schematic. Can Protel export to a pdf format? I think that would be the easiest. I can take screen shots but you end up loosing a lot of detail with screen shots. If I took a screen shot of the whole schematic it would look pretty fuzzy when you zoomed in once it was in pdf format. If I could export directly to pdf I could keep the detail. My system, although cumbersome, works. I output to a PostScript file, using a driver for one of the common color printers from HP, but causing it to be saved to a file. I then pull the file over to Linux and run it through ps2pdf, to convert to pdf format. I'm sure Adobe has a program that will do this all in Windows. (I run Win 2K as a guest OS under VMware, with Linux as the host OS.) Jon * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Exporting to pdf or Orcad or PSpice
I've beem using a free pdf writer for the last few months without problems. The free version pops up an IE advertisement when it writes. _http://www.pdf995.com/_ (http://www.pdf995.com/) Regards, Steve Allen Project Engineer Manufacturing Services, Inc. In a message dated 7/20/2004 2:55:40 PM Pacific Standard Time, [EMAIL PROTECTED] writes: Tis truly easy to print direct to a pdf from almost any application, including Protel EDA. Adobe Acrobat and a large number of third party PDF printer drivers are available. While Adobe's ~$200 package might be a bit overkill for most of us, the third party solutions range in price from around ten bucks to $40... A simple search on DejaNews (google) or at tucows (or similar) for pdf writer will turn up enough to allow you to trial and buy... I've been printing pdfs by selecting a pdf writer as the print device (ie, transparent and simple) for nearly a decade. aj * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
