Post by thread:[EE] SMD soldering in toaster ovens.

Alexandre Guimarães wrote: {Quote hidden}> Hi, > > Sorry for taking so long to get into the thread but I was far > behind on the list messages... > > Please be carefull when opening the oven door or putting a fan to > cool the boards faster ! Be very carefull.... All the manufacturers > specifications call for a maximun temperature gradient also on the > colling ramp and opening the oven door above 70 dg celsius will > stress the components ! That is specially true for SMD multilayer > capacitors, they will make micro-cracks with big temperature changes. > > The oven method is great for prototyping without precision > temperature control but if anyone is thinking about using it, as I > already do, for small production runs I strongly recommend using > proper temperature control for both the heating and colling ramps. I > ran a temperature profiler in my setup and I am sure I am not > violating the component manufacturers specs on the temperature and I > am quite sure it is not possible to be sure about it in a setup > without a temperature controller or with an open oven door ! > > My oven makes the soldering in about 6 minutes and cools in 2 more > minutes. If you need faster than that use 2 ovens ! > > Best regards, > Alexandre Guimaraes Alexandre, your above comments are very important, probably everybody is just overseen it. Doing experiments, I noticed that the profile temperature is not critical for the soldering quality. __ ____/ \ / | |\ _______/ | | \ / | | | \____ 100°F _____/ _ _ _ _|_ _ _|__|__ | _ _ A B C D |________|_____|__|___| A = PREHEAT 240 sec B = MELT 120 sec C = SOLDERING 45 sec D = COOL OFF 60 sec I made different tests basically changing temperature first; A = 180°F, 200°F, 220°F B = 300°F, 320°F, 340°F C = 400°F, 420°F, 450°F In any case, any combination, soldering was good, with few bridges. I guess above 400°F the paste melts and soldering happens, no matter what. Probably a better solder paste could reduce the bridges (any recommendations?). I also guess the temperature profile is more to protect the components than produce a good soldering. Alexandre, the above profile temp is adequate? can you comment or point some errors? Thank you. Wagner. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Hi, > Alexandre, your above comments are very important, probably everybody is > just overseen it. It is quite easy to eversee it, specially because the cracks are not visible most of the times. > Doing experiments, I noticed that the profile temperature is not critical > for the soldering quality. Yes it does ! It is just not visible.. The paste needs the right time at preheat to activate the flux and to evaporate the acids with no-clean flux. The liquid solder wetting is too fast the solder bellow will not work well, it it is too slow it will oxidize. There are some other problems with specific components that make changes in the profile mandatory. You should always check with the manufacturers datasheets to see if you are inside the right specifications. Follows some points that I sent to Roman quite a while ago offlist that are important by what I saw in some manufacturers specifications and also in private talks with people from the soldering industry: Some points that I think are worth and that should save you from some trouble: - Look for a 800 watts infrared oven, smaller than that you might have problems on the heating ramps. If you can find a forced air convection oven the results should be better because of better heat distribution. I did not find any ones down here, so I have not tried it myself. - Use solder paste with silver on it. The price is a little higher but some capacitors will not solder nicely with a common pb/sn solder. I use Kester solder paste. It is R276 if I remember right.. - Try many different profiles to see the one that works best on the board you are manufacturing. Each board is a different reality because of the different components density and IR absorption rates. - The solder should stay at the liquid state for more than 45 seconds and less than 90 seconds. Less time will make a bad solder joint and too much time will burn the components and possibly make a solder joint that has an intermetalic connection that is too thick and will be easily breakable by vibration and it will oxidize. - If you have compressed air use it with an eletro-pneumatic valve and electronics time control to make a dispensing unit that puts the right quantity of solder paste on the pads. > In any case, any combination, soldering was good, with few bridges. > I guess above 400°F the paste melts and soldering happens, no matter what. Like I said before it does matter but maybe not visible :-( Sometimes an xray inspections reveals voids and if the flux has not been correctly activated and evaporated it may leave acid residues on the board and inside the solder ball ! > Probably a better solder paste could reduce the bridges (any > recommendations?). The right temperature with the right solder will reduce the problem. I use Kester R276 with 2% of silver. No bridges at all !! > I also guess the temperature profile is more to protect the components than > produce a good soldering. It serves both purposes. Here is a link to the profile I used as a basis for my experiments. In practice I use a much longer preheat and flux activation phase because I prefer to be conservative on that. You will have to experiment because it really varies with the oven size and power and also from board to board. Depending on the board components density you may have to change it around. With a forced air convection oven you may be able to use just one profile but I have not tried that out. I also helps a lot to make your board as equally dense with components as possible. Remember that if a region has too many or too few components it will not heat or cool as the other regions of the board. http://www.iis.com.br/~alexg/profile.bmp If you have any more questions fell free to ask.. Best regards, Alexandre Guimaraes -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

While we're on the subject of SMD soldering, has anyone tried soldering BGAs with either a heatgun or a toaster oven? Just wondering... Later. -- Phil. spam_OUTphilpemTakeThisOuTdsl.pipex.com http://www.philpem.dsl.pipex.com/ -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

I have a PDF file that contains a description, circuit and software of a SMT toaster oven I built. I'd like to upload for public consumption. I can't see how to upload a PDF file to the PICLIST archive. Can somebody help with instructions on how to do this or provide me with a way to upload the file. Thanks Peter Homann .....Peter.HomannKILLspam@spam@adacel.com Adacel Technologies Limited, 250 Bay St, BRIGHTON, 3186, AUSTRALIA http://www.adacel.com <http://www.adacel.com> Telephone +61 (3) 8530 7777, Facsimile +61 (3) 9596 2960 Mobile 0421-601 665 -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

This oven talk is interesting. If it's so critical to get the profiles right using an oven, how come I seem to be able to hand solder SMD's with a great deal of butchery and still get working boards? (I have had one or two 1uF caps go crack on me though) ______________________________________________________ The contents of this e-mail are privileged and/or confidential to the named recipient and are not to be used by any other person and/or organisation. If you have received this e-mail in error, please notify the sender and delete all material pertaining to this e-mail. ______________________________________________________ -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Hi, > This oven talk is interesting. > > If it's so critical to get the profiles right using an oven, how come I seem to be able to hand solder SMD's with a great deal of butchery and still get working boards? (I have had one or two 1uF caps go crack on me though) It is not too critical, it is just a little critical :-) If you think better about it you will see that hand soldering produces less stress because it is much more localized and it takes much less time to make the solder joints ! My oven cycle takes 8 minutes and your hand soldering less than 10 seconds. It is the same problem that you have when using SOIC components in the oven process. You have to "bake" them for a while at 50 celsius to make sure you do not have any humidity inside the packages or they will crack in the oven. With hand soldering that is not necessary at all.. Getting the right profile done is quite easy and I got it working myself in few days, you just have to know what to look for and read all the manufacturers specs to make sure you are not violating the specs. A toaster oven with the right temperature control can give you a better profile than a cheap 3 zones conveyor oven !!! You just have to look at it carefully. Best regards, Alexandre Guimaraes -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Hi, Philip > While we're on the subject of SMD soldering, has anyone tried soldering BGAs > with either a heatgun or a toaster oven? > Just wondering... Not BGA's but I have soldered small adxl202 acelerometers that come in those weird ceramic packages and have pads bellow the surface. In my opnion BGA's would be too much for a small oven, even the big ones have trouble with them sometimes. I would not try smaller than 0805 and 0.50 pitch. When I need that kind of components you can afford a full size reflow oven ;=) Best regards, Alexandre Guimaraes -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Best bet is to register as a member at http://www.piclist.com (not the same as being a member of the PICList). Then you are entitled to free webspace. You can then post the link here. You may also be able to get James (the webmaster) to start a section about assembling SMT, if one doesn't exist already. Josh -- A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. -Douglas Adams Peter Homann wrote: > I have a PDF file that contains a description, circuit and software of a SMT > toaster oven I built. I'd like to upload for public consumption. I can't see > how to upload a PDF file to the PICLIST archive. > > Can somebody help with instructions on how to do this or provide me with a > way to upload the file. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Alexandre Guimarces wrote: > Please be carefull when opening the oven door or putting a fan to cool > the boards faster ! Be very carefull.... All the manufacturers > specifications call for a maximun temperature gradient also on the colling > ramp and opening the oven door above 70 dg celsius will stress the > components ! That is specially true for SMD multilayer capacitors, they will > make micro-cracks with big temperature changes. Alexandre is correct, I apologise for suggesting that just opening the door after soldering is a good way to do it. In reality our needs were quite different, ie only soldering a few SMD chips and no other components, and it wasn't "instantly" opening the door as it may have sounded. I posted that system in reply to someone who suggested it was difficult to do SMD in a cheap oven, and the main point I was trying to make was that it's not really difficult and no expensive controllers are needed. At the time we were using this simple stopwatch method I tested the system time over temperature and the different phases, ie oven preheat, on full, turn off, and door open, gave temperature in each phase that was close enough to the proper times and temperature ramps that it worked quite ok. If we had to solder the small parts (or larger areas of the PCB than just 1.5 square inches) I would go with the proper temp controller system as Alexandre has suggested. :o) -Roman -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

>Probably a better solder paste could reduce the bridges >(any recommendations?). Probably a little less paste, so it tends to pull back better due to surface tension and capillary action between the pad and pin. If you look at commercial SMD soldering, you will see that there really is very little solder on each pin, just enough to produce the nice meniscus between the pin and pad. If you have enough to allow the solder to bulge over the pad then you have too much. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam.....mitvma.mit.edu with SET PICList DIGEST in the body

Alan B. Pearce wrote: > > >Probably a better solder paste could reduce the bridges > >(any recommendations?). > > Probably a little less paste, so it tends to pull back better due to surface > tension and capillary action between the pad and pin. If you look at > commercial SMD soldering, you will see that there really is very little > solder on each pin, just enough to produce the nice meniscus between the pin > and pad. If you have enough to allow the solder to bulge over the pad then > you have too much. Also putting the line of paste closer to the end of the chip pins, (not close to the body) seems to help too. When they bridge it's mainly up against the chip body. -Roman -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email EraseMElistservspam_OUTTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

Here http://wwwbode.cs.tum.edu/~acher/bga/index.html is a webpage where someone built his very own BGA soldering station to solder a 256 ball BGA. I do not know if it is the most elegant way, but it worked... I should mention that the web page is only in german language (but there are a lot of pictures). Florian Voelzke Philip Pemberton wrote: {Quote hidden}> While we're on the subject of SMD soldering, has anyone tried soldering BGAs > with either a heatgun or a toaster oven? > Just wondering... > > Later. > -- > Phil. > philpemspam_OUTdsl.pipex.com > http://www.philpem.dsl.pipex.com/ > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email @spam@listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

> -----Original Message----- > From: pic microcontroller discussion list > [KILLspamPICLISTKILLspamMITVMA.MIT.EDU]On Behalf Of Florian Voelzke > Sent: Thursday, 21 November 2002 5:48 PM > To: RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU > Subject: Re: [EE] SMD soldering in toaster ovens. > > Ohhhhhh Noooooooooo It is pulling me under ....... Ok when I have a few $$ Spare, I will be going out and buying a Toaster Oven, Fan Forces, with Top and Bottom Elements... Voiding the waranty, Ripping the Guts out .... Building a uC interface with RS 232 output so I can data log the boards.... This sucker will be mean it will be a fighting machine ....... I will use an old Microwave front Panel with membrane keypad and Multi segment Vacume Flourecent Display..... This will be the .... V8 Super SMD soldering oven..... Tim Allen ;o) arrff arrff arrff ;o) --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.419 / Virus Database: 235 - Release Date: 13/11/2002 -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spamBeGonelistservspamBeGonemitvma.mit.edu with SET PICList DIGEST in the body

Katinka Mills wrote: > Ohhhhhh Noooooooooo It is pulling me under ....... > > Ok when I have a few $$ Spare, I will be going out and buying a > Toaster Oven, Fan Forces, with Top and Bottom Elements... Voiding the > waranty, Ripping the Guts out .... Building a uC interface with RS > 232 output so I can data log the boards.... This sucker will be mean > it will be a fighting machine ....... I will use an old Microwave > front Panel with membrane keypad and Multi segment Vacume Flourecent > Display..... This will be the .... V8 Super SMD soldering oven..... $29 at Target. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email TakeThisOuTlistservEraseMEspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

This sounds similar to what I have done. Wagner has kindly offered to host the document describing my SMT oven. It contains a description, software, circuit, etc. The link is; http://www.iis.com.br/~alexg/oven.pdf Enjoy, and don't be too harsh :-) Peter Homann RemoveMEPeter.HomannTakeThisOuTadacel.com Adacel Technologies Limited, 250 Bay St, BRIGHTON, 3186, AUSTRALIA http://www.adacel.com <http://www.adacel.com> Telephone +61 (3) 8530 7777, Facsimile +61 (3) 9596 2960 Mobile 0421-601 665 {Original Message removed}

Peter, Nice write-up. Have you logged/graphed any profiles or performance tests, etc ? Steve. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservEraseME.....mitvma.mit.edu with SET PICList DIGEST in the body