What Are The Characteristics Of SMT Processing And Assembly?
Date：2024/01/11 Click：150 times
As SMT processing assembly and interconnect used printed circuit boards must adapt to the rapid development of the current SMT chip assembly technology, SMT chip processing assembly printed circuit boards have become the mainstream products of the current SMT chip manufacturers, almost 100% of the circuit boards are SMT chip processing, its function is the same as the through hole PCB processing products. SMT chip processing has the following main characteristics:
1. High density: Because the number of SMT patch processing pins is as high as hundreds or even thousands of pins, the center distance of the pins can reach 0.3mm, so the high-progress BGA on the circuit board requires fine lines and fine spacing, the line width is reduced from 0.2~0.3mm to 0.1mm or even 0.05mm, and the double line between the 2.54mm grid has been developed to 4, 5 or even 6 wires. Thin lines and fine spacing greatly improve the assembly density of SMT. The corresponding SMT processing equipment with high precision can be completed by the corresponding SMT processing plant.
2, small aperture: most of the metallized holes in SMT are not used to insert component pins, and are no longer welded in the metallized holes, and the metallized holes are only used as an electrical interconnection between layers, so the aperture should be reduced as much as possible to provide more space for the SMT patch. The aperture has changed from 0.5mm in the past to 0.2mm, 0.1mm and even 0.05mm.
3, low coefficient of thermal expansion: any material will expand after heating, polymer materials are usually higher than inorganic materials, when the expansion stress exceeds the limit of the material will cause damage to the material. Because the SMT pins are many and short, the CTE between the device body and the SMT is inconsistent, and the device damage caused by thermal stress often occurs, so the CTE of the SMT board substrate should be as low as possible to adapt to the match with the device.
4, good high temperature resistance: Most of today's SMT circuit boards require double-sided mounting components, so the SMT chip processing circuit board is required to withstand two reflow welding temperatures, and today's multi-lead-free welding, welding temperature requirements are higher, and the SMT chip circuit board after welding is small deformation, no foaming, the welding pad still has excellent weldability, and the surface of the SMT chip circuit board still has a high smoothness.
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