眾所周知，電子設備和電路技術的不斷進步，在設計、開發和製造方面達到了工程藝術的頂峰。 印刷電路板 （PCB）已經被世界各地的人們目睹了。 Our planet is full of highly intelligent machines, automated robots and scientific marvels, and of course, there are plenty of PCBS in every corner of the planet, no matter what country or city it is. 然而，這些 PCBS 在功能、複雜性、製造成本、質量和可靠性方面確實有所不同。 本文重點討論最後兩點，PCBS的質量和可靠性。

是的，潛在客戶總是想要高質量的電子產品，但這非常昂貴，並且可能涉及復雜的製造過程。 在PCB製造、組裝和測試的複雜過程中，有一個非常重要的過程叫做PCB的“保形塗層”。 在質量和可靠性方面，這種敷形塗層在 PCBS 中非常重要。

什麼是敷形塗層及其重要性：

Conforming coating, an ultra-thin protective coating of polymer film, can be used in conjunction with assemblies mounted on assembly surfaces to protect assembly leads, solder joints, exposed wiring, and other metal points on the PCB surface from corrosion, dust, or chemicals due to various operating or environmental conditions.

保形塗層可以薄至 25 微米，並“符合”電路板的形狀和組件佈局。 如上所述，在 PCB 的表面（頂部和底部）應用保形塗層的原因是為了保護 PCB 免受不利的外部環境條件的影響，從而增加 PCB 和相關電子設備的使用壽命。

與工業、工廠和大功率電子產品中的高溫一樣，這些帶有敷形塗層的 PCBS 可以承受極端溫度。 同樣，安裝在靠近海洋或海洋的地區/地區的電子設備可能會受到高濕度的影響，例如導航電子海軍設備可能會受到腐蝕/侵蝕，從而導致金屬氧化。 Similarly, in microbiology laboratories and the medical industry, sensitive electronic equipment can be exposed to toxic chemicals, acidic and alkaline solvents that can accidentally spill onto a PCB, but the PCB’s “conformation coating” will protect the PCB and components from fatal injury.

如何應用保形塗料？

In fact, the method of applying “conformal paint” in the right way is so important that careful consideration must be given to how conformal paint is applied. It is as important to choose suitable conformal coating materials.

決定敷形塗料正確應用的主要因素是：

1- 油漆厚度

2- The level of coverage achieved

3- The degree of adhesion of paint to wood panels and their components.

There are five methods for applying conformal coatings:

1-用刷子手工繪畫

2- 氣溶膠塗層

3- Atomizing spray gun coating

4- Automatic dip coating

5- Automatic selection of coating

三防漆固化/乾燥方法：

Conformal coatings themselves can be classified according to the drying and curing methods used after conformal coatings are completed. These methods are:

1- Heat/heat curing: Conformal coating is dried at high temperature. Drying rate is much faster than normal room temperature drying/curing.

2-冷凝固化：PCB的保形塗層在環境溫度下乾燥，大氣中的水分會減慢固化或乾燥過程。

3- ULTRAVIOLET (UV) curing: Here PCB with conformal coating is exposed to UV radiation. The uv energy determines the curing speed of PCB conformal coating

4- 氧化固化：在這種方法中，PCB 構象異構體暴露在含有大量氧氣的露天環境中，這將有助於溶劑型構象異構體的干燥/固化

5- Catalytic curing: This is the process of curing conformal coating in which two materials are fused together, one of which is conformal coating. 一旦塗層與其他催化劑材料融合，固化過程在完成之前不能停止。

Classification of conformal coatings:

There are five main conformal coatings used: acrylic resin, epoxy resin, silicone, polyurethane (PU) and polyparaxylene coating.

L 丙烯酸樹脂（AAR）：

Acrylics are ideal for (low-cost and high-volume) common electronics because AAR is inexpensive and can be easily applied to PCB surfaces by brush, dip, and manual or automatic spraying, reducing turnaround time and producing cost-effective products.

為妳而設的優點:

1 – 低成本

2- 易於手動或自動機器人應用

3- Easy to rework

4- 出色的防潮保護

5- Good surface elasticity, can withstand static voltage discharge, and does not react with the atmosphere, therefore helps cure through solvent evaporation

缺點：

1- Due to the use of atmospheric curing/drying methods for this material, proper ventilation systems need to be ensured

2- 低粘度維護

3- 低耐磨性和耐化學性

L Epoxy conformal coating (ER) :

基於環氧樹脂的敷形塗層可以通過手刷、噴塗或浸塗來完成。 建議對較大體積和較小體積或原型 PCBS 進行噴塗。

為妳而設的優點:

1- High moisture resistance and good dielectric resistance

2- Excellent chemical resistance, abrasion resistance, moisture resistance and high temperatures up to 150 O C

缺點：

1-epoxy conformal paint is very hard and rigid and can damage PCB and its components if attempted peeling or removal. 使用危險溶劑去除塗層

2-低溫性能差

3- 高固化收縮率

4-它們很難重做

L 矽樹脂 (OSR) 敷形塗層：

The softest of the above two types of conformal coatings is silicone resin (OSR) conformal coatings. They are widely used in LED lamp PCBS without reducing light intensity or color change. Ideal for PCB installation at high humidity and exposure to air. Suitable for PCB with high operating temperature and high power

為妳而設的優點:

1- 良好的耐化學性、防潮性、鹽霧和高達 200 OC 的高溫

2- 良好的柔韌性使其能夠抵抗外部環境對 PCB 的振動應力。

3- 適用於高濕度的 PCB 戶外應用

壞事：

1- 由於橡膠特性不耐磨

2- 可以返工，但不容易，需要特殊溶劑、長時間浸泡和像刷子或超聲波浴一樣攪拌

3- Low mechanical strength, weak adhesion to PCB substrate

L 聚氨酯 (PU) 敷形塗層：

適用於汽車、工業、儀器儀表和電信領域的 PCB 應用。 特別是在航空航天領域，燃料蒸氣不斷與電子設備主體碰撞，從而滲透到內部並影響PCB板

為妳而設的優點:

1- High resistance to moisture, chemicals (acid and alkali) and wear

缺點：

1-經過長時間的完全固化過程，由於其VOC含量高，在高溫下容易變黃

2-像矽一樣，不容易完全去除

L polyparaxylene conformal coating:

This type of coating is suitable for avionics, microelectronics, sensors, high-frequency circuits, and densely populated PCB-based components. It is applied by means of vapor deposition.

為妳而設的優點:

1- 優異的介電強度

2- High resistance to moisture, solvents, extreme temperatures and acid corrosion

3- Can be applied evenly with very thin paint.

缺點：

1-拆卸/返工非常困難

2-成本高是最大的缺點。