SMT process is now more and more mature for electronics manufacturing. What are the main features of SMT PCB Assembly process, today China SMT factory will introduce to you.
1. High density
Since the number of pins processed by SMT is as high as hundreds or even thousands, the center distance of the pins can reach 0.3mm. The high-precision BGA on the circuit board requires fine lines and fine spacing, and the line width is reduced from 0.2~0.3mm to 0.1mm or even 0.05mm, the double wire between the 2.54mm grid has developed to 4, 5 or even 6 wires. Thin lines and fine pitches greatly increase the assembly density of SMT.
2. Small aperture
Most of the metallized holes in SMT are not used to insert component pins, and no welding is performed in the metallized holes. The metallized holes are only used as electrical interconnections between layers, so the aperture should be reduced as much as possible to provide more space for the SMT. The aperture has changed from 0.5mm in the past to 0.2mm, 0.1mm and even 0.05mm.
3. Low thermal expansion coefficient
any material will expand after heating. Polymer materials are generally higher than inorganic materials. When the expansion stress exceeds the material bearing limit, the material will be damaged. Due to the many and short SMT pins, the CTE between the device body and the SMT is inconsistent, and device damage caused by thermal stress occurs from time to time. Therefore, the CTE of the SMT circuit board substrate should be as low as possible to suit the matching with the device.
4. Good high temperature resistance
Today, most circuit boards today need to install components on both sides. Therefore, SMT processed circuit boards need to be able to withstand two reflow soldering temperatures. At present, lead-free soldering is widely used, and the soldering temperature is higher. After soldering, the circuit board is required to have small deformation and no blistering, the pads still have good solderability, and the surface of circuit board still has a high flatness.
SYS Technology is an electronics contract manufacturing factory since 2006, with SMT lines and wave soldering line in house. We have 100+ professionals waiting to service you. Contact us today: sales@syspcb.com.
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