Saturday, December 18, 2010

【 Weak current College 】 SMD integrated circuit desoldering 】

1 clearance SMD integrated circuit

Use the Remove method of picking pin SMD integrated circuit, too cumbersome, time consuming, slightly careless that may damage the pads, to create difficulties when welding circuit. Author clearance SMD integrated circuit using plastic welding torch, the use of its high temperature hot blast blowing out will solder to melt. I am using Zhejiang Wenzhou production-electronic thermostat 700 watts, electronic market sell, estimated at around $ 80. When you first put down integrated circuit board carried out from the machine, the IC pins painted pine scent, and then power up the welding torch, temperature up to Max, right hand torch at IC pins move quickly, so that each pin turns heating, left hand pointed pliers IC a PIN, solder completely melted, lift the left hand quickly integrated circuit, in the early ready for alcohol after thermal for misjudgment.

2 cleaning pads

IC removed, pads also has many residue Tin will give heavy welded IC difficult, must be clean. Use absorb rope on Rosin, Bentham and a Tin ceiling. Suction is important to note that absorb rope move direction to follow the trend of pads, do not traverse, otherwise easily damaged pads. After cleaning residual Tin, with cotton wool dipped in alcohol to clean residual Rosin.

3 welding

SMD integrated circuit features a PIN pad for fine, thin, selection of the appropriate electric iron and solder wire welding is the key to success. The author is Guangzhou yellow electronics electric appliances factory of production of the 35-Watt internal thermal long-life soldering iron, soldering iron tip fine without oxidation, dip it after heating, the occurrence of the very bright Rosin, suitable for welding of SMD components. E-markets have sold, approximately $ 20. Solder wire I use 08 mm would contain Tin of 65% of the unknown with Rosin solder wire (Japanese, can't read). This solder wire weight right, moderate with Tin. Solder wire too thick to welding, containing tin content is too low impact welding results.

Welding of the IC pins painted pine scent, and IC pin and printing plate pads where accurate positioning. The four corners welding cell, and then check it once again confirm that the integrated circuit each pin is correct and the location of their land. And then the boards erected (need help), left hand solder wire, right hand soldering iron, soldering iron and Board into a 35 degree angle from the right side of the previous IC pin welding, soldering iron and solder wire down together, using the flow of Hot Tin will lead and pad welding firm. From the last PIN to the next pin, if it has two pins or more pin welded together, repeat above the surface tension of the use of rosin adjacent two feet apart. After welding, throw out a remnant of Tin, about the occurrence of the Rosin cleaning dip, so that it remains clean. Turn the motherboard, and then repeat the previous action, after all pin welding. If there are individual pin also welded together, can absorb rope suction opening, in repair welding, respectively. Use alcohol to clean the PIN IC residual Rosin, drying or air-dry, entire desoldering work knot speed.


Soldering iron welding force must decline, mainly using gravity makes hot welding solder flow to. Too hard easily pin bending, causing trouble.

In addition, welding solder easy flow of the fraternities, welding completed to carefully check the clean residual Tin, prevent losses after powerup.

Initial training in the welding method is excatly VCD Board exercises (such as Samsung 802 motherboard), the Board of IC in the back of the motherboard, the surrounding no discrete components, will not affect the soldering iron welding process moving, and decoding Board of SMD integrated circuits and discrete components in the same plane, affect the soldering iron, causing inconvenience to welding. Welding of plate may be out of the way of discrete componentsbe removed after the IC IC and discrete components.

This method is typically only required to exercise 3 — 5 times to proficiency. Familiar, welding of integrated circuit and the factory for the difference of no welding. This method is simple, easy, save time and effort and high efficiency.

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