Post by thread:[OT:] SMT and the Hobbyist!

Picdude wrote: > > SO's are solderable by hand, using a small soldering iron > tip. > Hi Neil, As you have mentioned, SOICs can be neatly hand soldered with a fine-tip soldering iron aided by thin solder, flux and patience. But when you realise you have to remove an SMD part from the board for whatever reason, the nightmare starts. If it's a 1206 or 0805 resistor, then it's not so much of an issue. Even if you destroy the part in the process of desoldering and removing it, the cost is too little to bother about it. But when you have to remove say, a 16-pin SOIC without damaging it, what is the best method? Using a hot air pencil may be one of the ideal solutions. But if you don't have it, what can be the best alternative? Regards, Bala -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

I've done this only once, and successfully, with a 8-pin SOIC, by first removing as much solder as possible with some copper braid (fluxing the braid works wonderfully), then lightly bending each pin up as it's desoldered. I used a small utility knife for this. When it was off, I carefully re-bent the pins. Took a freakin' long time, but it worked. And each chip would probably only survive one desoldering before the pins break off. Cheers, -Neil. On Thursday 25 September 2003 01:25, spam_OUTBala.ChandarTakeThisOuTAVENTIS.COM scribbled: {Quote hidden}> Hi Neil, > > As you have mentioned, SOICs can be neatly hand soldered with a fine-tip > soldering iron aided by thin solder, flux and patience. But when you > realise you have to remove an SMD part from the board for whatever reason, > the nightmare starts. If it's a 1206 or 0805 resistor, then it's not so > much of an issue. Even if you destroy the part in the process of > desoldering and removing it, the cost is too little to bother about it. But > when you have to remove say, a 16-pin SOIC without damaging it, what is the > best method? Using a hot air pencil may be one of the ideal solutions. But > if you don't have it, what can be the best alternative? > > Regards, > Bala --- [This E-mail scanned for viruses] -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

{Quote hidden}> -----Original Message----- > From: .....Bala.ChandarKILLspam@spam@AVENTIS.COM [SMTP:Bala.ChandarKILLspamAVENTIS.COM] > Sent: Thursday, September 25, 2003 7:26 AM > To: .....PICLISTKILLspam.....MITVMA.MIT.EDU > Subject: Re: [OT:] SMT and the Hobbyist! > > Picdude wrote: > > > > > SO's are solderable by hand, using a small soldering iron > > tip. > > > > Hi Neil, > > As you have mentioned, SOICs can be neatly hand soldered with a fine-tip > soldering iron aided by thin solder, flux and patience. But when you > realise > you have to remove an SMD part from the board for whatever reason, the > nightmare starts. If it's a 1206 or 0805 resistor, then it's not so much > of > an issue. Even if you destroy the part in the process of desoldering and > removing it, the cost is too little to bother about it. But when you have > to > remove say, a 16-pin SOIC without damaging it, what is the best method? > Using > a hot air pencil may be one of the ideal solutions. But if you don't have > it, > what can be the best alternative? > A technique I have used with some success is to pass a length of enamel copper wire behind a row of legs, and solder the end of the wire to a suitable point on the board. You can then gently pull the wire as you apply the soldering iron to each pin in turn. The wire lifts each pin and ensures the solder joint is broken. Generaly with PCB's I work with are 10+ layer and worth far more than the IC's so (if I don't have access to the proper removal kit) I would usualy cut the legs of an IC to lessen the chances of damaging the board. Regards Mike ======================================================================= This e-mail is intended for the person it is addressed to only. The information contained in it may be confidential and/or protected by law. If you are not the intended recipient of this message, you must not make any use of this information, or copy or show it to any person. Please contact us immediately to tell us that you have received this e-mail, and return the original to us. Any use, forwarding, printing or copying of this message is strictly prohibited. No part of this message can be considered a request for goods or services. ======================================================================= Any questions about Bookham's E-Mail service should be directed to EraseMEpostmasterspam_OUTTakeThisOuTbookham.com. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> A technique I have used with some success is to pass a length > of enamel > copper wire behind a row of legs, and solder the end of the wire to a > suitable point on the board. You can then gently pull the > wire as you apply > the soldering iron to each pin in turn. The wire lifts each > pin and ensures > the solder joint is broken. Thanks to Neil, Roy & Mike. Now I have a few more tricks in my bag to try out! Using an enamelled copper wire seems promising since the enamel will prevent the wire from getting soldered to the pins of the IC while it is being used to break the solder joints of each pin. I guess the gauge of the wire should be around 38 or 40 to be suitable for the job. Regards, Bala -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

I have raised pins on a surface mount chip with a needle. My prefferred method, however, is to saw the %&$^%*(! thing off with a small dremel tool and a tiny abrasive blade, then wipe off the ramining leads with a hot soldering iron, and clean off the board with flux remover to get the copper powder off. I ruin the least amount of pads this way. I also make custom sodering iron tips. Take an aluminum block, and mill out a section in the middle that fits over the IC so the edges touch the leads. Drill a hole in the middle and swedge it over an old worn out soldering iron tip. Then you install it in your iron (I use Weller irons, which make this possible, your iron may have a tip assembly that prevents this) and viola! A custom chip remover. Heat the chip and gently slide it sideways off the pins. 25% fo the time, by any method, you will screw up pads and have to add a change order wire to fix it. -- Lawrence Lile Picdude <picdudespam_OUTNARWANI.ORG> Sent by: pic microcontroller discussion list <@spam@PICLISTKILLspamMITVMA.MIT.EDU> 09/25/2003 02:11 AM Please respond to pic microcontroller discussion list To: KILLspamPICLISTKILLspamMITVMA.MIT.EDU cc: Subject: Re: [OT:] SMT and the Hobbyist! I've done this only once, and successfully, with a 8-pin SOIC, by first removing as much solder as possible with some copper braid (fluxing the braid works wonderfully), then lightly bending each pin up as it's desoldered. I used a small utility knife for this. When it was off, I carefully re-bent the pins. Took a freakin' long time, but it worked. And each chip would probably only survive one desoldering before the pins break off. Cheers, -Neil. On Thursday 25 September 2003 01:25, RemoveMEBala.ChandarTakeThisOuTAVENTIS.COM scribbled: > Hi Neil, > > As you have mentioned, SOICs can be neatly hand soldered with a fine-tip > soldering iron aided by thin solder, flux and patience. But when you > realise you have to remove an SMD part from the board for whatever reason, > the nightmare starts. If it's a 1206 or 0805 resistor, then it's not so > much of an issue. Even if you destroy the part in the process of > desoldering and removing it, the cost is too little to bother about it. But > when you have to remove say, a 16-pin SOIC without damaging it, what is the > best method? Using a hot air pencil may be one of the ideal solutions. But > if you don't have it, what can be the best alternative? > > Regards, > Bala --- [This E-mail scanned for viruses] -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

But > when you have to remove say, a 16-pin SOIC without damaging it, what is the > best method? Using a hot air pencil may be one of the ideal solutions. But > if you don't have it, what can be the best alternative? Using a hot air station is the best alternative, say Weller WMD-1. If you don't have one, then get one. Regulating the air flow and the temperature you will do the job quickly and well. Never had any crap in my eyes or destroyed any pad. The only problem I still have is inspecting the quality of the joints under the BGA ic's. VV --------------------------------- Do you Yahoo!? The New Yahoo! Shopping - with improved product search -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

But > when you have to remove say, a 16-pin SOIC without damaging it, what is the > best method? Using a hot air pencil may be one of the ideal solutions. But > if you don't have it, what can be the best alternative? Using a hot air station is the best alternative, say Weller WMD-1. If you don't have one, then get one. Regulating the air flow and the temperature you will do the job quickly and well. Never had any crap in my eyes or destroyed any pad. The only problem I still have is inspecting the quality of the joints under the BGA ic's. VV Unless you have an X Ray machine or vision like Superman.... --------------------------------- Do you Yahoo!? The New Yahoo! Shopping - with improved product search -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

"Roberts II, Charles K." <spamBeGonerobertsckspamBeGoneORNL.GOV> wrote: >>The only problem I still have is inspecting the quality of the joints >>under the BGA ic's. >>VV >Unless you have an X Ray machine or vision like Superman.... That's the problem I don't have an X ray machine, not at the moment. Right now I send the boards to a company which does have one, they charge a little fee for soldering the bga's and inspecting the joints. VV --------------------------------- Do you Yahoo!? The New Yahoo! Shopping - with improved product search -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics