Nowadays, with the rapid development of SMT patch assembly technology, almost all circuit boards are processed by patch processing. Therefore, SMT patch processing and assembly printed circuit boards have become the mainstream products of current SMT patch manufacturers. Although its functions are the same as those of through-hole circuit board processing, their respective characteristics and performance are different. The following Sanjing mainly introduces the characteristics of SMT processing and assembly:

First of all, the first one is high density: because the number of pins processed by the SMT patch can reach hundreds or even thousands, and the center distance of the pins can reach 0.3mm, the high-precision BGA on the circuit board requires fine lines, fine pitches, and line widths. From 0.2~0.3mm to 0.1mm or even 0.05mm, the double wire between 2.54mm grid has developed to 4, 5 or even 6 wires. The fine lines and fine pitch greatly improve the SMT assembly density.

The second is the small aperture: the aperture has changed from 0.5mm in the past to 0.2mm, 0.1mm or even 0.05mm. Nowadays, most of the metallized holes in SMT are not used to insert component pins, and the holes are no longer soldered, but only used as electrical interconnections between layers, so the hole diameter should be reduced as much as possible , Provide more space for SMT patch.

The third is the low coefficient of thermal expansion: we know that no matter what material it is, it will expand after being heated. Polymer materials are usually higher than inorganic materials. When the expansion stress exceeds the material's maximum endurance, it will cause damage to the material. Due to the many and short SMT pins, the CTE between the device body and the SMT is inconsistent, and damage to the device caused by thermal stress often occurs. Therefore, the CTE of the SMT circuit board substrate is required to be as low as possible. Adapt to the matching of the device.

The last one is good high temperature resistance: nowadays most of the circuit boards need double-sided mounting components, so the circuit boards processed by SMT are required to be able to withstand two reflow soldering temperatures. In addition, most of them are now lead-free soldering. The soldering temperature requirements are also higher. It is required that the SMT patch should not be deformed or blistered after soldering, and the pads should still have excellent solderability, and the surface of the SMT patch circuit board should still have a high degree of smoothness.

The above is about the characteristics and performance of SMT processing and assembly, I hope it can be helpful to everyone!