PCB科技 - PCB電路板電鍍工藝科技介紹

電鍍銅工藝科技介紹 PCB電路板 electroplating processing

The main feature of 這個 electroplated hole copper plating processing technology used by the 電路板 製造商生產多層阻抗 電路板 是在多層膜的“芯板”中形成的微通孔的盲孔和埋入通孔嗎 PCB電路板. 微通孔需要通過鑽孔和鍍銅實現層間電互連. 這種用於孔金屬化和電鍍的盲埋孔的最關鍵方面是獲取和更換電鍍溶液.

Circuit board manufacturers manufacture multi-layer PCBs by coating or laminating a dielectric layer (or resin-coated copper foil) on the surface of the "core board" and forming micro-vias. 這些在“芯板”上分層形成的微通孔是通過光誘導法等方法製成的, 电浆法, laser method and sandblasting method (mechanical method, 包括未介紹的數控鑽孔方法, 等.) Made. These micro-vias on 多層PCB電路板 need to be metallized and copper electroplated to achieve electrical interconnection between PCB layers. 本節主要介紹PCB板在鑽孔和電鍍過程中微通孔的特性和要求.

對於通孔, 如果是垂直孔板, the PCB製造商 可以搖擺, 振動, 攪拌電鍍液, or spray flow in the plate making fixture (or hanger) to make the PCB on the two plates of the plate. 它們之間存在液壓壓差. 這個液壓差將迫使電鍍溶液進入孔中，並驅走孔中的氣體以填充孔. For high aspect ratio (thickness to diameter ratio: the ratio of the thickness of the dielectric layer to the micro-via hole) Small holes, 這種液壓壓差的存在更為重要, 然後進行孔形成或電鍍. 孔電鍍過程中, part of the Cu2+ ions in the plating solution in the hole must be consumed. 因此, the Cu2+ concentration of the plating solution in the hole is getting lower and lower, 孔形成或電鍍的效率將越來越低. In addition to the effect of the plating fluid in the through hole (such as a "laminar flow" phenomenon, 等.) and the uneven current density distribution (the electric current density in the hole is much lower than the current density on the plate surface), 因此, 孔的中心塗層的厚度始終低於板表面塗層的厚度. 為了减少鍍層厚度的差异, the most fundamental method is: one is to increase the flow rate of the plating solution in the hole or the number of exchanges of the plating solution in the hole per unit time (assuming that the plating solution is changed again and again, 其實很複雜, but this assumption can explain the problem); the second is to increase the current density in the hole, 這顯然是困難或不可能的, 因為新增孔中鍍液的電流密度必然會新增板表面的電流密度, 因此, it will cause a greater difference between the thickness of the plating layer in the center of the hole and the thickness of the plate surface; the third is to reduce the current density during electroplating and the concentration of Cu2+ ions in the plating solution, and at the same time Increase the flow rate of the plating solution in the hole (or the number of exchanges of the plating solution), 以這種管道, can reduce the difference of Cu2+ ion concentration in the plating solution between the plate surface and the hole (referring to the difference between partial consumption of Cu2+ and replacement of the plating solution. Cu2+ concentration difference), this measure and method can improve the difference between the thickness of the plating layer on the board and the plating layer in the hole (at the center), but it is often at the expense of PCB productivity (yield), 這也是不可取的. 第四, 脈衝電鍍法的使用, 根據不同的高厚徑比微孔, 相應的脈衝電流電鍍方法{可以顯著改善PCB板表面電鍍和孔中電鍍層厚度之間的差异, 甚至可以達到相同的塗層厚度. 這些措施是否適用於多層微通孔的孔電鍍 PCB電路板s?

如前所述, 多層膜中微通孔的孔鍍 電路板s在盲孔中進行. 當盲孔的孔深較小或厚徑比較小時, 實踐表明，上述四種電鍍措施都能取得良好的效果. 然而, 當盲孔深度較大或厚徑比較大時, 微通孔電鍍的可靠性如何? 換句話說, 如何控制盲孔的深度或多層膜的適當厚徑比 電路板?

至於使用水准孔電鍍來處理多層PCB中的微通孔, 沒有詳細報告, 但可以想像，對於PCB厚度與直徑之比, 使用水准孔電鍍. 應提供可靠的電力互連. 對於具有較大縱橫比的盲孔, 多層膜下表面上的盲孔 電路板 很難排出孔中的氣體, 電鍍液甚至很難進入孔中, 更不用說孔中電鍍溶液的交換問題了, 除非板面定期翻轉.

綜上所述, 根據上述多層PCB板鑽孔電鍍加工的基本特點和基本原理, 我們可以得出結論，多層膜中的盲孔和埋孔 電路板 are processed by horizontal hole plating (especially the Large aspect ratio, such as aspect ratio>0.8), 遠不如垂直孔電鍍的效果.