Here is the abstract you requested from the Passives_2007 technical program page. This is the original abstract submitted by the author. Any changes to the technical content of the final manuscript published by IMAPS or the presentation that is given during the event is done by the author, not IMAPS.
|PCB Screen Printing Process for Embedded Capacitors and Resistors in RF Application|
|Keywords: Embedded Passives, RF module, PCB|
|The technology of embedded passives in PCB has been applied more common in communication devices. And there are many different processes to implement embedded passives into PCB. Screen printing is one of the most cost effectively procedure in PCB manufacturing. This work developed the embedded resistors and capacitors that were implemented by using conventional PCB screen print process with new resistive and capacitive materials. The property of resistive material is 10K Ohm/square, and the capacitive material keeps high dielectric constant 50 at 1GHz. For RF application, a 2.4GHz power amplifier module with 4 printed resistors, 8 printed capacitors and 4 inductors built in PCB was implemented. The bias circuit using printed resistors and the impedance matching circuit by printing capacitors were been well designed into PCB. The PA module was originally designed by using 19 SMT (R: 5, C: 10, L: 4) components. Thus 84.2% high replacing rate of passives was reached. Only one resistor and two decoupling capacitors remained SMT components. Since the character of embedded one is different from SMD intrinsically, new electrical model of passives should be constructed for design reference. The tolerance, loss and reliability issues are defects of PCB screen printing, the design of these printed components for RF circuit should have some compensation to overcome these problems. Without any trimming of the embedded components, the developed PA module has measured 24.7dB gain, 25.5dBm P1dB and 39.5dBm IP3, which keeps good performance at 2.41~2.47GHz band for WLAN application. Thus the success of PCB embedded passives by screen print process is the fastest and most cost effective method than others for mass production.|
|Chang-Sheng Chen, Vice Project Manager
Industrial Technology Research Institute