General Principle Of Hand Welding For PCBA Circuit Board Assembly

When a large number of PCBA is welded by machine, if we find a few defective solder joints or high temperature sensitive components, we will use the old hand welding process to remedy it. In addition to the generalized hand welding soldering, welding and welding is another silver etc..

One, welding torch hand welding

This is the most basic welding method, the first tool of the welding gun is also commonly known as the iron. The heating body and the iron head can provide enough heat for the solder wire and the workpiece to be processed, so that it can be welded at high temperature. Due to the heating process of welding transformer will generate electromagnetic waves so New problems crop up unexpectedly. torch, but also possess good isolation function, so as to avoid the "electric pressure" or "ESD" damage to the IC PCB surface sensitive element. The welding should pay attention to the project a lot, such as the type of iron head shape shall be suitable for processing, temperature control sensitivity, heat conduction speed, work temperature before the operation of fast enough recovery temperature is high enough for stability, convenient operation, easy maintenance etc. are for reference.

Two, solder wire

The various weight ratios of tin lead alloy composition, then adding sandwich, solid flux cores, and pumping metal strips made of filamentous solder can be used to pull, welding and filling the mechanical strength of solder joints has become known. The flux should pay attention to corrosion. Whether the insulation resistance of the residue after welding is high enough, so as to avoid the problem of poor electrical insulation of the subsequent PCBA assembly panels. It is sometimes found that when flux is insufficient, fluxes can also be added to help them, but careful attention should be paid to the subsequent ion contamination of these liquid fluxes.

Three, welding process and key points of welding torch hand

(1) to the iron head and wire no rust cleaning, and contact to the position of welding, the molten tin appears quickly after the attachment and filling effect, the tin solder iron head more broken, the water wet sponge to remove.

(2) melt into a proper amount of tin wire and make it evenly dispersed, and not too much. The welding flux can provide a double function of cleaning and heat transfer.

(3) the soldering iron head must be continuously exposed to the welding position to provide enough heat until the solder has been evenly distributed.

(4) be careful when the welding gun is removed after completion, to avoid the misconduct caused by the disturbance of the solder joint before curing and to damage the strength of the solder joint.

(5) when the assembly to be processed into single PCB parts, and the joint area is big and more, can be no other parts of the panel in a hot plate paste is preheated; so will accelerate the operation speed and reduce the local overheating of the surface damage, the preheating can also be used small fan the special.

(6) a tool with a soldering iron head as a heat transfer and replenishment of tin should have the maximum contact area for the area to be processed to reduce the time loss of heat transfer. In order to enhance the efficiency of transporting solder raw materials, and keep the surface must maintain good solderability, and not cause the accumulation of various residues, once the iron head is oxidized or excessive, it must be replaced.

(7) hand welding operations at small or fine legs, in order to avoid overheating damage, additional temporary heat dissipation accessories, such as metal crocodile clips, can be added.


(Source: internal information)

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