The study of the Stability of Pd/PVP Nanoparticles added with Phosphoric Acid and the Activity to Electroless Cu Deposition

磷酸對奈米鈀粒子穩定性及其在無電鍍銅沉積催化活性之研究

周沛瑜(Pei-Yu Chou)

指導教授 ： 萬其超 ； 王詠雲

國立清華大學/工學院/化學工程學系/碩士(2009年)

https://doi.org/10.6843/NTHU.2009.00260

摘要

Palladium nanoparticles were synthesized simply by reducing Pd ions which were attracted to electron nitrogen atom in poly(N-vinyl-2-pyrrolidone) (PVP). This Pd/PVP aqueous system was developed as the activator for electroless copper deposition. Compared with commercial Pd/Sn colloid that was easily oxidized by dissolved oxygen and agglomerated in the solution, Pd/PVP activator was stable without any Pd aggregation for a long time. Pd/PVP activator showed high catalytic activity as Pd/Sn colloid on flat FR-4 substrate (glass fiber reinforced epoxy). From back-light test for printedthrough-hole (PTH) process, we found that micro-etching process would reduce catalytic activity of Pd/PVP activator and voids in PTH occurred
especially on glass fiber. Adding phosphoric acid to Pd/PVP activator could improve back-light performance, but Pd nanoparticles precipitated in a few days.
In this study, we found that H3PO4 molecule was the cause of Pd agglomeration by forming hydrogen bond with PVP. Pd nanoparticles would precipitate if the concentration of H3PO4 were high in the solution. IR spectra
and UV-vis spectra proved that Pd/PVP activator would react with H3PO4 molecules to form a complex by hydrogen bond, and DLS analysis also showed that Pd/PVP/H3PO4 nanoparticles formed a larger hydrolysis cluster than
Pd/PVP nanoparticles. TEM images gave the information about particle size and shape of Pd nanoparticles, and more information about dispersion and distance of Pd nanoparticles and Pd clusters could be obtained by the model
fitting of SAXS data. The results showed that Pd/PVP/H3PO4 nanoparticles formed a looser structure than Pd/PVP nanoparticles, and H2PO4 anion would result in PVP to twist Pd nanoparticles tightly, which reduced the catalytic
activity of Pd/PVP/H2PO4 nanoparticles for copper deposition. SEM images showed that micro etching made the surface of glass fiber rough, and more Pd nanoparticles could be adsorbed in the holes. However, catalytic activity for Cu deposition was low because outer Pd nanoparticles shielded active surface of inner Pd nanoparticles. Since there is higher Cu deposition on epoxy when we use Pd/PVP/H3PO4 nanoparticles as activator, in PTH process, Cu deposition on glass fiber is improved by Cu deposition on epoxy nearby. So back-light performance become acceptable for PCBs industry.

關鍵字

奈米鈀 ； PVP ； 磷酸 ； 無電鍍沉積

並列摘要

本論文主要探討磷酸對於鈀奈米粒子穩定性及在對無電鍍銅沈積催化活性的影響。在高分子PVP作為保護劑下，鈀離子經由甲醛還原成鈀奈米粒子，可作為無電鍍銅沈積製程之催化銅還原活化劑。不同於商業化所使用的錫鈀膠體，二價錫離子容易被溶氧而氧化使得鈀粒子沈澱，此高分子型奈米鈀具有更好的穩定性，在FR-4基板上亦有很高的催化活性，但是鍍通孔實驗結果發現通孔內鍍銅效果不佳，在玻纖處出現孔破缺陷。添加磷酸於奈米鈀活化劑中可以改善鍍通孔的效果，但是卻造成鈀粒子聚集沈澱。
在本論文中，我們發現磷酸分子是造成奈米鈀活化液不穩定的原
因。當溶液中磷酸濃度過高時會導致奈米鈀聚集。由IR和UV光譜圖發現磷酸分子會與PVP高分子產生氫鍵而形成錯合物，DLS結果亦顯示了加入磷酸後的奈米鈀與PVP形成較大的水合團簇。TEM圖提供了奈米鈀粒子顆粒大小與分散情形，利用模型分析SAXS結果得知奈米鈀粒子間與團簇間的距離和分散情形。結果顯示磷酸使得高分子奈米鈀結構更為鬆散，而磷酸二氫根陰離子造成PVP更緊密的纏繞於奈米鈀，進而降低了奈米鈀的催化活性。從SEM圖發現微蝕製程會造成玻璃纖維表面粗糙化，粗糙的表面可以吸附較多的奈米鈀，但是外層的奈米鈀會遮蔽內層奈米鈀的催化活性，使得玻纖布上無電鍍銅結果不佳。加入磷酸後的奈米鈀粒子在環氧樹脂上可以催化較多的無電鍍銅量，也因此在鍍通孔實驗中，即使玻纖處的無電鍍銅效果不佳，但可以憑藉環氧樹脂提高玻纖處的無電鍍銅反應，使得背光結果可以達到工業要求。

並列關鍵字

Palladium nanoparticles ； PVP ； Phosphoric acid ； Electroless deposition

參考文獻

4. C. L. Lee, Y.Y. Wang and C.C. Wan, J. Electrochem. Soc., 150, C125 (2003).

8. W. Reppe, “Polyvinylpyrrolidon” Verlag Chemie, Weinheim (1954).

10. Verall, R. E. in 'Water: A Comprehensive Treatise' (Ed. F. Franks), 3, Plenum (1975).

12. Z. Zhang, B. Zhao and L. Hu, J. Solid. State Chem., 121: 105 (1996).

13. A. Güner, J. of Applied Polymer Science, 75, 1434–1439 (2000).