Manual welding procedure for patch components:

1. Clean and fix PCB (printed circuit board)

Check the PCB to be soldered before welding to ensure dry.To remove the oily hand prints and the oxides of the above surfaces, they will be removed without affecting the tin.When soldering PCB manually if the condition allows, can use the welding machine such as fixed by the welding, usually by hand fixed good, it is worth noting that the influence is to avoid finger touch pad on the PCB on the tin.

2. Fixed patch elements

The fixation of the patch is very important.According to the tube foot of the patch, the fixed method can be divided into two kinds – one-foot fixed method and multi-foot fixation method.For the small number of pins (generally 2-5), the patch elements such as resistance, capacitance, diode, and triode are generally used with single leg fixation.That is to put a solder on the plate.

Then take the tweezers in the left hand and place the device in the installation position and light up the circuit board. The right hand handle the solder iron near the solder plate.The element is not moving after welding a solder plate, and the tweezers can release.In the case of the multi-sided chip chip, the single foot is difficult to fix the chip, so it needs to be fixed to the foot, which can be used for the fixed foot (see figure 5).Welding fixed a tube foot and then welding the tube foot across the foot of the tube to achieve the fixed purpose of the whole chip.It is important to note that the tube foot is much more and the thick patch chip, the accurate tube foot aligned welding plate is especially important, should be carefully checked and checked, because the welding is good and bad is determined by this premise.

It is worth emphasizing that the chip’s pin must be judged correctly.

, for example, sometimes we secured the chip carefully even welding finished, check to find corresponding errors – pin pin as the is not the first foot first foot to weld!Repent and regret!Therefore, these meticulous early work must not be careless.

3. Welding the remaining pins

After the element is fixed, the remaining tube feet shall be welded.For the small part of the foot, you can use the solder in your left hand and iron in your right hand.For chip pins and more intensive, in addition to spot welding, can adopt welding, namely on the pin on one side of the tin and then use soldering iron to the solder to melt into the side of the rest of the pin on the erase (see figure 6), molten solder can flow, so sometimes can also be the board suitable tilt, and excess solder.It is worth noting that, whether soldering or welding, it is easy to cause the adjacent tube foot to be short-circuited by tin.Don’t worry about that, because you can get to the point that all pins and pins are well connected to the solder, and there is no false welding.

Remove excess solder

In step 3, the short circuit of the tube caused by welding is mentioned. Now how to deal with the excess solder.In general, you can suck the excess solder out of the tin belt.Suction tin with the use of the method is very simple, to absorb with adding suitable amount of flux (such as rosin) then close to solder, use clean welding head on the suction tin take, to absorb with heated to adsorption pad on the solder melts, slowly from the bonding pad to the other end of the light at the end of the pressure drag, soldering is inhaled.Should pay attention to is the end of the tin, absorption should be welding head and absorb in the tin tin take out of bonding pad at the same time, this time if the suction tin with glue on the pad, don’t pull tin with absorption, but to absorb with add flux or to heat with welding head suction tin belt to make it smoothly and then gently pull out of bonding pad and to prevent the hot components around.If there is no special tin belt sold in the market, you can use copper wire in the wire to control the tin belt.The method is as follows: after stripping off the outer skin of the electric wire, exposing the copper wire inside it, the soldering iron is used to melt some of the rosin on the copper wire.Remove excess solder after the effect.In addition, if the welding result is not satisfactory, the solder can be reused to remove solder and resolder the element.

Clean the soldering area

After soldering and removing excess solder, the chips are basically soldered.However, due to the use of rosin and tin to absorb tin, there are some rosin on the sides of the chip tube on board, although it does not affect the work and normal use of the chip, but it is not beautiful.And it may be inconvenient to check.It is necessary to clean up these remnants.The usual cleaning method can be used for washing board water. In this case, alcohol is used for cleaning, cleaning tools can be used for cotton swabs, or using tweezers for toilet paper.When cleaning and erasing, it should be noted that alcohol should be in moderation, and its concentration should be high, so as to quickly dissolve the residue of rosin.Secondly, the force path to be erased must be controlled, not too large, to avoid the abrasion resistance welding layer and to the chip pin.The cleaning effect is shown in the figure.A soldering iron or a hot air gun can be used to properly heat the alcohol to allow the residual alcohol to evaporate quickly.At this point, the welding of the chip is finished.

Summed up

In summary, the welding patch elements are generally fixed – welding – to clean up such a process.The fixing of the elements is the precondition of welding, and be patient to ensure that each pin and its corresponding welding disc are aligned accurately.When welding tube feet more chips, the pin is solder short circuit don’t worry, can use suction tin belt for welding or just use soldering iron absorption use solder melt flow factors after remove excess solder.The mastery of these skills is, of course, practiced.Limited to space reasons, this paper only on more than one pin chip welding demo, for many other types of the SMT chip pins, the pins intensive, mechanical strength, and the number in the case of different welding methods are basically the same, just the detail processing is slightly different.Therefore, to be a good player in the welding piece, you need to practice more to improve your proficiency.If the conditions permit, you can use the old circuit board old chip and so on.