PCB部落格 - PCB板純錫電鍍缺陷

1 簡介：在生產過程中 印刷電路板, 由於成本因素，大多數製造商仍然使用濕膜技術進行成像, 這將不可避免地導致諸如“流血”之類的問題, bright edge (thin tin)" and other undesirable problems when electroplating pure tin in graphics. 鑒於此, 我將與您討論我多年來總結的純鍍錫工藝常見問題的解決方案. 其中, 電路板的電鍍工藝大致可分為：酸性光亮鍍銅, 鎳/電鍍金, 和鍍錫. 本文介紹了電路板的加工過程, 電鍍工藝科技和工藝流程, 以及具體的操作方法. 工藝流程：酸洗全板鍍銅圖案轉移酸脫脂二次逆流漂洗微蝕刻二次逆流漂洗酸浸泡鍍錫二次逆流漂洗逆流漂洗酸浸泡圖案電鍍銅-二次逆流漂洗-鍍鎳-二次水洗-檸檬酸浸泡-鍍金 -回收-2-3級純水洗滌-乾燥.

2. Analysis of the reasons for "滲水板" of wet film board (quality problem of non-pure tin syrup)
2.1絲網印刷前刷過的銅表面必須清潔，以確保銅表面與濕油膜之間具有良好的附著力.
2.2當濕膜的曝光能量較低時, 濕膜的光固化將不完整, 純錫的耐電鍍性較差.
2.3濕膜預焙參數不合理, 而且烤箱的局部溫差很大. 由於光敏資料的熱固化過程對溫度敏感, 低溫會導致不完全的熱固化, 從而降低濕膜對純鍍錫的電阻.
2.4缺乏後固化/固化處理降低了純鍍錫的電阻.
2.5電鍍純錫板必須徹底清洗. 同時, 每個板必須插入機架或幹板中, 不允許堆放板材.
2.6濕膜品質問題.
2.7生產和儲存環境和時間的影響. 惡劣的存儲環境或長時間存儲將導致濕膜膨脹，降低其對純鍍錫的阻力.
2.8錫缸內的純錫光劑和其他有機污染物侵蝕和溶解濕膜. 鍍錫槽陽極面積不足時, 電流效率將不可避免地降低, and oxygen evolution during the electroplating process (electroplating principle: anode oxygen evolution, cathode hydrogen evolution ). 如果電流密度過高且硫酸含量高, 陰極會放出氫, which will attack the wet film and lead to the occurrence of tin penetration (that is, the so-called "seepage plating").
2.9 The high concentration of the stripping solution (sodium hydroxide solution), high 溫度 or long soaking time will produce tin flow or dissolved tin (that is, the so-called "seepage plating").
2.10純鍍錫電流密度過高. 通常地, 濕膜的質量電流密度適用於1.0和2.0A/dm2. 超出此電流密度範圍, 某些濕膜質量容易出現“滲鍍”.

3. Causes and 改進ment countermeasures of "seepage plating" caused by the problem of potion
3.1原因：藥水問題導致“滲鍍”的產生主要取決於純錫光亮劑的配方. 光劑具有很强的滲透能力，在電鍍過程中對濕膜的侵蝕會產生“滲透”. 那就是, 當添加過多純錫光亮劑或電流稍大時, 出現“滲水鍍層”. 在正常電流操作下, 由此產生的“滲透鍍層”與藥劑的不受控操作條件有關, 如純錫光亮劑過多., 高電流, 硫酸亞錫或硫酸含量高, 等., 這些會加速對濕膜的侵蝕.
3.2改進對策：大多數純錫光亮劑的效能决定了它們在電流作用下對濕膜更具侵蝕性. 為了避免减少濕膜純鍍錫的“出血”, 建議在平時生產濕膜電鍍純錫. The board must do three things:
1) When adding pure tin light agent, 必須在少量時間內進行監測, and the content of pure tin light agent in the plating solution is usually controlled at the lower limit;
2) The current density is controlled within the allowable range;
3) The control of the composition of the potion, 如將硫酸亞錫和硫酸含量控制在下限也有利於改善“滲水鍍層”.

第四, the characteristics of market pure tin light agent
4.1一些純錫光亮劑僅限於電流密度，且工作範圍相對較窄. 這種純錫光亮劑通常容易濕膜“出血”. 它控制硫酸亞錫的操作參數, 硫酸和電流密度相對. The allowable standard range is also narrow;
4.2一些純錫光亮劑適用於廣泛的電流密度操作. 這種純錫光亮劑通常不易產生濕膜“滲錫”. 這是相對硫酸亞錫的工况參數控制允許標準, 硫酸和電流密度. wide range;
4.3一些純錫光亮劑容易“漏鍍”, seepage plating, blackening" or even "glowing" at the edge of the wet film;
4.4 Some pure tin brighteners do not cause the problem of "brightness" of the edge of the wet film (no baking or UV curing), 但仍然存在“流血”問題, 可以通過烘烤或UV固化. improve. 在濕膜板上進行純鍍錫工藝之前, 未經烘烤或UV固化處理，線路邊緣不存在“光亮和滲透鍍”問題. 現時, 市場上真的很少有純錫光亮劑. 具體操作應基於不同糖漿供應商提供的純錫光亮劑的特性, 以及工作電流密度等參數, temperature, 陽極面積, 硫酸亞錫, 應嚴格控制硫酸和錫光亮劑的含量.

5. The reason for the "brightness" of the line edge caused by pure tin plating on the wet film board
Because the formula of pure tin light agent generally contains organic solvent, 濕油膜本身由有機溶劑和其他資料組成, 兩者之間不相容, 尤其是線條邊緣的“亮度”. Factors related to the "shiny" of the line edges:
5.1 Pure tin polish (under normal circumstances, the formula will contain organic solvents);
5.2 The current density is low (the lower the current density, the easier it is to produce "brightness" on the edge of the line);
5.3 The conditions of the baking board are inconsistent (the main purpose of the baking board is to volatilize the organic solvent of the wet oil film);
5.4 The thickness of the screen printing wet oil film is uneven (the thicker the oil film, the easier it is to "glow");
5.5 The quality of the wet oil film itself (choose the wet oil film to match the electroplating pure tin potion);
5.6 The quality of the acid degreaser in pretreatment (selecting a good acid degreaser not only enhances the water washability of the solution, but also greatly reduces the probability of remaining on the copper surface after degreasing);
5.7 Excessive tin light agent in the plating solution (too much tin light agent will cause organic pollution of the plating solution, 為了防止濕膜鍍錫板隨著生產能力的新增而污染錫筒, 每半月進行8小時的碳芯過濾, 同時電解5小時, 2.5小時零分.5小時，電流密度為5ASF, 10ASF and 15ASF every week);
5.8 It is related to temperature (the higher the temperature, 低電位區的位置越不均勻, 試驗證明，溫度越高, 越容易產生線條邊緣的“亮度”. 此外, the high temperature accelerates the oxidation of Sn2+ and the consumption of additives.);
5.9 Poor conduction (poor conduction directly causes the current density to be seriously low, 當電流密度低於10ASF時, the edge of the line is likely to "glow").
5.10 The wet film board should be stored for a long time (the wet film plated pure tin board should be stored in a workshop with a relatively good environment, 儲存時間不得超過72小時. 圖形電鍍過程中的工作人員將根據生產條件取板, 但在電鍍車間的儲存時間不得超過72小時. 12 hours);
5.11 Insufficient anode area of pure tin plating bath (insufficient anode area of tin plating bath will inevitably lead to lower current efficiency and oxygen evolution during electroplating process. 陰陽極面積之比一般為2～3:1, 純錫槽陽極間距標準為5cm左右, whose purpose is to ensure sufficient anode area). 因此, 一些不好的問題實際上是由某個過程中不顯眼的細節引起的. 只要你從多個方面考慮, 你可以找到問題的關鍵並解决它.

6. Master the advantages and disadvantages of wet film quality in the market
A good quality wet film is very beneficial to reduce the "brightness" of the line edge, 但不能完全消除. 此外, 更適合純鍍錫板的油膜不一定是良好的油膜. The following briefly introduces the quality characteristics of wet film:
6.1良好的濕膜不易產生“滲鍍”, 當電流密度較高時，油膜不容易分解, and the film is relatively easy to remove;
6.2某些濕膜確實可能在降低線條邊緣的“亮度”問題方面發揮一定作用, 但要去除薄膜相對比較困難. 這種濕油膜不適用於電流密度範圍大的藥劑, 並且容易產生稍高的電流密度. “電鍍, 薄膜3明治, “發黑”甚至油膜破裂等問題.
關於電鍍錫, 1) purpose and function: the purpose of pure tin in graphic electroplating mainly uses pure tin as a metal anti-corrosion layer to protect circuit etching; 2) the bath is mainly composed of stannous sulfate, 硫酸和添加劑； 硫酸亞錫的含量控制在35克左右/公升, 硫酸控制在10%左右； 鍍錫添加劑的添加一般採用千安培小時法或根據實際生產板效果進行補充； 電鍍錫電流計算一般為1.5安培/平方分米乘以可在板上電鍍的面積； 錫筒的溫度保持在室溫, 一般不超過30度, 更容易控制在22度, 所以在夏天因為溫度太高, it is recommended to install a cooling temperature control system for the tin cylinder; 3) Process Maintenance: replenish tin-plating additives in time according to the thousand ampere hours every day; check whether the filter pump is working properly and whether there is air leakage; every 2-3 hours, use a clean wet cloth to clean the cathode conductive rod; every week Regularly analyze stannous sulfate (1 time/week) and sulfuric acid (1 time/week) in the tin cylinder, 通過霍爾電池測試調整鍍錫添加劑的含量, 並及時補充相關原材料； 每週清潔陽極導電棒和箱體兩端的電力連接器； 低電流電解0.2到0.5 ASD，每週6-8小時； 每月檢查陽極袋是否損壞, 並及時更換損壞的； 檢查陽極袋底部是否有陽極污泥堆積, 如有必要, 應及時清洗； 每月用碳芯連續過濾6至8小時, 低電流電解去除雜質； 大約每六個月, it is determined whether large-scale treatment (activated carbon powder) is required according to the pollution status of the bath liquid; every two weeks Replace the filter element of the filter pump; 4) Major treatment procedure: A. 取出陽極, 拆除陽極袋, 用銅刷清潔陽極表面, 沖洗並乾燥, 放入陽極袋, 放入酸槽備用B. 將陽極放入袋中，在10%堿液溶液中浸泡6至8小時, 用水沖洗, 然後浸泡在5%的稀硫酸中, 用水沖洗並乾燥以備日後使用； C. 將儲罐液體轉移至備用儲罐, 然後按每公升3到5克. 活性炭粉末緩慢溶解到罐液中. 解散完成後, 吸附4-6小時. 使用10um聚丙烯濾芯和助濾劑粉末將槽液過濾到清潔的工作槽中. 根據0. 2-0. 5ASD電流密度低電流電解6至8小時, D. 實驗室分析後, 調整罐內硫酸和硫酸亞錫含量至正常工作範圍內； 根據霍爾電池測試結果補充鍍錫添加劑； E. 電解板顏色均勻後, 停止電解； F. 試鍍可以. 添加硫酸時, 注意安全. When the amount of sulfuric acid is large (more than 10 liters), 應分幾次緩慢添加； 否則, 鍍液溫度過高, 亞錫會被氧化, 浴的老化會加速 PCB板.