> -----Original Message----- > From: Jon Elson [mailto:[email protected]] > Sent: 05 July 2017 23:25 > To: [email protected]; Rob Jarratt <[email protected]>; General > Discussion: On-Topic and Off-Topic Posts <[email protected]> > Subject: Re: ChipQuik Troubles > > On 07/05/2017 03:42 PM, Rob Jarratt via cctalk wrote: > > I bought some ChipQuik recently and managed to successfully remove a > > 74LS125 with little trouble. Today I have come to trying to desolder > > another similar sized chip, but try as I might I just cannot get it to > > work. The ChipQuik just balls up and won't "take" to the pins. I > > applied plenty of the flux supplied with the ChipQuik, but I wonder if I applied > too much? > > > > > > > > > The solders may be incompatible. What are you trying to do, replace a > defective chip to make an old board work? >
I *think* it may be defective, I have a replacement for it anyway. > You DON'T need ChipQuik. If the board was soldered with lead-free solder, > diluting the solder with PbSn solder makes it easier. If it is already done with > leaded solder, then you just need a little technique. For surface mount parts, > use an Xacto knife under the pins, and lift them one at a time while touching > with the iron. Generally, I remove as much solder as I can with solder wick first, > then lift the pins. When one row of pins are lifted, the chip can be flexed a few > times and the other row of pins break off. The remaining pins can be swept off > with the soldering iron. > Then, the solder can be removed with solder wick and the new chip installed. > If all else fails I may go with this. I don't mind if the chip is damaged during removal as I have replacements. Thanks Rob > For through hole chips, the safest way is to snip the pins off at the chip body > with tiny diagonal cutters, remove the body and then pick each lead out with > tweezers while heating the pad with the soldering iron. Also, with good > desoldering tools, you can remove the chip without destroying it. The best > desolderers have a vacuum pump (or air venturi pump) and a hollow > desoldering tip. You apply the tip to the lead for about 5 seconds, then apply > the vacuum while "swirling" the tip around the component lead. > This works amazingly well, and the parts generally fall off the board when all > leads are done, even on multi-layer boards. The solder suckers that are used > with a standard iron are FAR inferior to the units described above. > > Jon
