利用低成本液態晶體聚合物基板結合覆晶封裝技術之射頻應用

Abstract

此研究主要探討低成本的液態晶體聚合物基板(Liquid Crystal Polymer, LCP)應用於覆晶封裝結構之高頻特性的研究。LCP基板因為具有較小的介電常數以及較小的loss tangent，這說明了LCP在封裝基板的應用中成為有潛力的選項。 使用HFSS模擬了 LCP上50 Ω CPW 傳輸線的高頻特性，在0~110GHz 間，其結果顯示反射損失(reflection loss, S11) < -20 dB，且介入損失(insertion loss, S21) < -1 dB。此外，具有CPW 傳輸線的GaAs 晶片與LCP基板的接合模擬結果中可以發現，適當的補償設計可以有效的改善特定頻率的高頻特性。最後主動元件(High Electron Mobility Transistors, HEMT)被封裝在LCP基板上，它的DC 與 S參數的量測結果顯示封裝前後的特性只有些許的衰減，呈現了優秀的特性，這顯示出LCP基板適合使用在高頻封裝的應用當中。

This study focuses on low-cost liquid crystalline polymer (LCP) substrate for high frequency flip-chip packaging applications. LCP substrate has low dielectric constant and low loss tangent, exhibiting a potential candidate for high frequency packaged. A coplanar transmission line structure on LCP substrate was simulated by high frequency simulation software (HFSS). The result show the reflection loss < -20 dB and the insertion loss < -1 dB in the frequency range of 0~110 GHz. The simulation results also showed suitable compensation design can improve the performance in specific frequency range with a CPW GaAs chip mounted LCP substrate. Finally, a high electron mobility transistor was flip-chip bonded on LCP substrate, the DC and S-parameter measurement showed mild degeneration before and after flip-chip bonding. The results showed LCP substrate is suitable for high frequency packaging applications.