In the production process of PCB, surface treatment technology is a very important step, which not only affects the appearance of PCB, but also directly affects the functionality, reliability, and durability of PCB. The surface treatment process can provide a protective layer, prevent copper corrosion, enhance welding performance, and provide good electrical insulation properties. The following is an analysis of several common surface treatment processes in PCB production.

PCB production

1、 HASL (Hot Air Leveling)

Hot Air Flattening (HASL) is a traditional PCB surface treatment technique that involves immersing the PCB in a molten tin/lead alloy and then using hot air to "flatten" the surface, forming a uniform metal coating. The HASL process has a lower cost and is suitable for various PCB manufacturing, but there may be issues with uneven solder pads and inconsistent metal coating thickness.

2、 ENIG (Chemical Nickel Gold)

Chemical Nickel Gold (ENIG) is a process of depositing nickel and gold layers on the surface of a PCB. Firstly, the copper surface is cleaned and activated, then a thin layer of nickel is deposited through chemical displacement reaction, and finally a layer of gold is plated on top of the nickel layer. The ENIG process provides good contact resistance and wear resistance, making it suitable for applications with high reliability requirements, but the cost is relatively high.

3、 Chemical gold

Chemical Gold is the direct deposition of a thin layer of gold on the surface of a PCB. This process is typically used for applications that do not require welding, such as radio frequency (RF) and microwave circuits, as gold provides excellent conductivity and corrosion resistance. The cost of chemical gold is lower than ENIG, but not as wear-resistant as ENIG.

4、 OSP (Organic Protective Film)

Organic protective film (OSP) is a process of forming a thin layer of organic film on the surface of copper to prevent copper oxidation. OSP technology is simple and cost-effective, but it provides relatively weak protection and is suitable for short-term storage and use of PCBs.

5、 Hard Gold

Hard Gold is a process of depositing a thick layer of gold on the surface of a PCB through electroplating. Hard gold is more wear-resistant than chemical gold and is suitable for connectors that require frequent insertion and removal or PCBs used in harsh environments. Hard gold has a higher cost than chemical gold, but provides better long-term protection.

VI Immersion Silver

Immersion Silver is a process of depositing a silver layer on the surface of a PCB. Silver has good conductivity and reflectivity, making it suitable for visible and infrared applications. The cost of silver immersion process is moderate, but the silver layer is prone to sulfurization and requires additional protective measures.

7 Immersion Tin

Immersion Tin is a process of depositing a tin layer on the surface of a PCB. The tin layer provides good soldering performance and certain corrosion resistance. The cost of tin dipping process is relatively low, but the tin layer is prone to oxidation and usually requires an additional protective layer.

8 Lead-Free HASL

Lead Free HASL is a RoHS compliant HASL process that uses lead-free tin/silver/copper alloys instead of traditional tin/lead alloys. The lead-free HASL process provides similar performance to traditional HASL, but meets environmental requirements.

There are various surface treatment processes in PCB production, each with its unique advantages and application scenarios. Choosing the appropriate surface treatment process requires consideration of the PCB's application environment, performance requirements, cost budget, and environmental standards. With the development of electronic technology, new surface treatment processes continue to emerge, providing PCB manufacturers with more choices to meet the constantly changing market demands.