Hdi Rigid-flex Pcb Buried Vias Process

Printed circuit board (PCB) is now becoming one of the main support products in the electronic information industry. The application of special PCB such as HD Iboard,IC packaged board,rigid-flex board,buried component board,optical-electrical PCB represents the current PCB industry development trends. And the development trends of electronic products requires PCB to be smaller,lighter,high speed,high frequency and more functional.To suit the development trends, more and more blind/buried via structure was applied in HDI rigid-flex PCB. Such structure can shorten the wire dimension, reduce the transmit delay time of information, improve PCB characteristic impedance and increase the design freedom. This work was supported by Zhu Hai Topsun Electronic Technology Co.,Ltd. According the blind/buried via structure and metalizing theory, we did some research on the blind/buried via manufacture process. And the main works were:1. We tested focus on the UV laser drilling and the suitable blind/buried via drilling process was researched. The main effect factors, such as pulse width,frequency,speed,focus height, which were the technological parameters of drilling process, were discussed in details by conducting an orthogonal experimental design (OED) study. The regression equations between via depth and drill parameters had been successfully obtained: YCu =136-2.21X1+6.25X2+0.656X3-0.0106X4-0.106X22-0.00303X32 YFR-4 =1058-5.52X1-13.2X2-4.52X3-0.0143X4+0.17X22+0.0144X32In these equations above, the YCu and YFR-4 represent the relevant depth of via,while the X1,X2,X3,X4 represent pulse width,frequency,mark speed, focus height. And the test result of the metallographic slicing tester showed that we can success fabricate 100μm micro blind via using these equations. Then we studied the CO2 drilling process, and summarized the differences between the two process.2. The via cleaning process, mainly the application of plasma cleaning, weather suitable in blind/buried via were discussed. And we conclude that we needn't pass the plasma cleaning process after the UV drilling. Then we did some research on the hole break-out in the black hole process and finally found the suitable solution method. And we successful carried out the chemical plating experiment in the laboratory. The influence of a new additive SPS was studied in the chemical plating process, and we gave the reasonable explanation to how the SPS influence on the plating rate.3. The copper fill process was studied in the later time, the main work included how the main effect factors such as current density,additive consistence,plating time worked on different micro via. Based on these results, we speculated the filling theory during the experiments, and the"bottom-up"filling theory which was studied hotly outside was introduced.4. There were many process in the manufacture of HDI rigid-flex PCB and the mutual effect between different process was very important, so chose the right material and process was the key point. In the help of product line workers, we finally success manufactured a new type of six layer HDI rigid-flex PCB, which contain second-order blind via and the thickness was much smaller than usual six layer board. At last we success tested the copper filling technology applied in the whole board manufacture process.