The first pass yield is the lifeline of a patch processing plant. Some companies must reach 95% of the first pass yield to meet the standard line. Therefore, the first pass yield is high or low, reflecting the technical strength of the chip processing factory, process quality. The high throughput rate can improve the company's capacity efficiency, reduce production costs, and most importantly, can be stable delivery and improve customer satisfaction.
The rate of meeting shipping standards in one go.
First pass yield specifically means: the number of good products that have passed all tests the first time the process is put into 100 sets of PCBs in the production line. Therefore, products that pass the test only after rework or repair by the production line are not part of the first pass yield calculation.
1. materials (including various electronic components material in the early stage, also including PCB boards)
2. solder paste
3. the quality and mentality of employees
First pass yield is related to the profitability and lifeline of the enterprise, so each chip factory is grasping the optimization and improvement of the first pass yield, 100% certainly can not reach, but also hope to have more than 98%.
1. Optimize the pcb board stencil design
More than 70% of the welding quality in the solder paste printing process, which is the SMT industry summed up the experience data, solder paste printing is the forefront of the process, solder paste offset, pull tip, collapse, in many cases is the stencil design defects, stencil may be too large / small, stencil hole wall rough, etc. will cause the above-mentioned bad, which leads to pcb pads on the paste is bad, resulting in poor soldering, thus affecting the straight-through rate. Thus affecting the first pass yield.
2. Choose the right type of solder paste
Solder paste is a mixture of a variety of metals and fluxes, similar to toothpaste, solder paste is divided into 5, 3 and other different types of solder paste, different products need to choose a different solder paste for printing.
3. Adjust the stencil printer squeegee angle, pressure
The pressure and angle of the scraper of the printing machine will affect the factor of solder paste, the pressure is large, it will cause less solder paste, and vice versa, the angle is best 45-60 degrees range.
4. Reflow oven temperature curve
According to the different products, adjust the preheating time, reflow temperature curve, using the furnace temperature tester, close to the actual temperature of production, and then get the furnace temperature curve, and then adjust the furnace temperature curve, so that the furnace temperature curve in line with the solder paste and product soldering requirements.
