[Wire Harness] Five PCBA soldering techniques

In the traditional electronics assembly process, wave soldering is generally used for mounting over-hole cartridge (PTH) printed board assemblies.

Wave soldering has many shortcomings.

① can not be distributed in the welding surface of high-density, fine-pitch SMD components.

② bridging, leaky soldering more.

③ need to spray flux; printed board by the larger thermal shock warpage deformation.

As the current circuit assembly density is increasingly high, the welding surface will inevitably be distributed with high-density, fine-pitch SMD components, the traditional wave soldering process has been unable to do anything about it, generally can only be soldering surface SMD components alone for reflow soldering, and then manually fill the remaining plug-in solder joints, but there is poor quality consistency of the solder joints.

5 new hybrid welding processes

01

Selective Soldering

In selective soldering, only some specific areas are in contact with the solder wave. Since the PCB itself is a poor heat transfer medium, it does not heat up and melts the solder joints in the adjacent components and PCB areas during soldering.

02

Dip soldering process

Using the dip selection soldering process, you can weld 0.7mm to 10mm solder joints, short pins and small size pads are more stable and the possibility of bridging is also small, the distance between the edges of adjacent solder joints, devices, and solder nozzles should be greater than 5mm.

03

Through-hole Reflow Soldering

Through-hole Reflow (THR) is a process that uses reflow soldering technology to assemble through-hole components and shaped components.

04

Wave soldering process using shielding molds

Since conventional wave soldering technology cannot cope with the soldering of fine-pitch, high-density SMD components on the soldering surface, a new method has emerged: wave soldering of cartridge leads on the soldering surface is achieved by masking the SMD components with a shielding die

05

Automatic soldering machine process technology

Since the traditional wave soldering technology cannot cope with the soldering of double-sided SMD, high-density SMD components, and components that are not resistant to high temperatures, a new method has come into being: the use of automatic soldering machines to achieve the soldering of the soldering surface inserts.

Summary

Which welding process technology to choose depends on the product characteristics.

(1) If the product batch is small and there are many varieties, then you can consider selective wave soldering process technology without making special molds, but the investment in equipment is larger.

(2) If the product type is a single, large batch, and wants to be compatible with the traditional wave welding process, then you can consider the use of shielding mold wave welding process technology, but need to invest in the production of special molds. These two welding technology processes are better controlled, so in the current electronic assembly, production is being widely used.

(3) through-hole reflow soldering due to the process control is more difficult, the application of the former relatively less, but to improve the quality of welding, rich welding means, reduce the process, are very helpful, but also a very promising means of development of welding.

(4) automatic soldering machine process technology is easy to master, is a new type of welding technology developed faster in recent years, its application is flexible, small investment, maintenance and low cost of use, etc., is also a very promising development of welding technology.