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PCB/PCBA knowledge
PCB Tinning – What Is It And What Are The Tinning Solutions

When you manufacture a PCB, you’ll have to coat it with several materials, and that results in a number of lamination layers on your PCB. PCB tinning is a sort of lamination layer on any PCB. If you’re not sure what exactly is PCB tinning, then this article will walk you through every detail associated with it.

Table of Contents

What is PCB tinning?

There’s a fine layer of solder coating applied on the PCB traces and other conductive materials. That’s called PCB tinning. The concept of PCB tinning is to apply a soldering coating on the copper traces, pads, and vias, which will aid the soldering process later during PCBA. PCB tinning ensures protection against oxidation, and solder bridging improvises solderability, and helps avoid any need for repair and rework.

What are the PCB tinning pros and cons?

Advantages

  1. It Aids Soldering During PCBA
    The tinning process leaves your PCB with a smooth, clean and even layer of solder on the top. That helps in proper soldering later during the PCBA process. As a result, you can expect better adhesion of solder between the vias and the component pins.
  2. Your PCB’s Lifespan Will Increase Dramatically
    By tinning, you’re adding an added layer on your PCB that offers several types of protection to it. As a result, you’re increasing your PCB’s lifespan dramatically. Moreover, soldering will be strong due to tinning and that’ll also result in high-quality PCBs.
  3. You Can Save Money By Opting For Tinning
    Tinning is one of the several options for surface finishing. However, other surface finish options are very expensive as compared to tinning. That’s why most manufacturers prefer tinning and its cost-effectiveness has made it so popular in the PCB and electronics industry.

Disadvantages

  1. It’s An Added Cost
    While you’ll love the benefits of PCB tinning, it’s also contributing to the increased cost of PCB. Added PCB manufacturing cost will ultimately impact your overall product’s price.
  2. It Leaves An Impact On The Environment
    Most people are not concerned about the harmful impact on the environment that the tinning chemicals leave. But the concerned people know how much harm they’re causing to the environment by opting for tinning.
  3. High-temperature Applications Can Cause Trouble
    If you’ve tinned your PCB, it can cause some impedance and thermal issues when working in high-temperature. Therefore, the PCB manufacturer needs to make sure that such things don’t happen.

What is the electroplating method of PCB tinning?

Electroplating method of PCB tinning
Electroplating method of PCB tinning

The electroplating method states that your PCB manufacturer will make a layer of tin on the PCB’s copper traces and copper pads. It’ll do so by dipping the PCB in an electrolyte solution. Then an electric current will be passed to the solution, which will ultimately enable the tin to settle on the copper surfaces.

When the current will be passed to the electrolyte solution, tin will react and its ions will automatically deposit on the copper surface, leaving other metals and non-metals on the PCB untouched.

What is the PCB tinning process?

1.Preparing The PCB
The PCB maker will clean up the PCB surface, so there’s no residue or foreign particles present on the surface.

2.Applying The Flux
A layer of flux is needed so that a strong bond between the tin and the copper can be created.

3.Selecting A Tinning Method
Based on your requirements, your PCB maker will select the most appropriate tinning method. Some common tinning methods used in the PCB industry include:

●Hot Air Leveling: A molten alloy such as tin-lead or tin-silver-copper is chosen and the PCB is given a bath in it. However, that leaves the PCB with excess solder, which is later removed by blowing hot air on the surface.
Electroless Nickel Immersion Gold: The PCB maker will put a thin layer of nickel on the copper through a chemical process, followed by a layer of gold over nickel. This is why you’ll notice some expensive gadgets’ PCBs have gold traces.

4.Post-tinning Treatment
It’s highly likely that the PCB maker will have to do some post-tinning treatment, such as excess solder removal, surface polishing, post-tinning clean up, etc.

How to tinning a PCB board

What are the common defects and solutions during PCB tinning?

  • Insufficient & Uneven Tinning
    This happens when the solder coverage is insufficient or the temperature distribution wasn’t proper at the time of PCB tinning. To solve this issue, the PCB maker needs to put enough flux and has to adjust the temperature parameters during the tinning process.
  • Too Much Tinning & Solder Bridging
    When a lot of solder is put, the tinning gets overloaded, which eventually leads to solder bridging. The excess solder flows to the nearby regions, causing a bridging when in a molten state. To avoid or overcome this issue the PCB maker needs to apply solder in medium amounts, so that it’s neither too less nor too much. Also, a proper solder mask can be applied so that it can resist solder bridging to some extent.
  • Oxidation Or Contamination
    Sometimes, due to improper cleaning prior to the PCB tinning process, the PCB makers might experience oxidation or contamination trapped in the tinning. This highly affects the conductivity and can cause overheating. Your PCB maker can resolve this issue by ensuring proper storage conditions for the PCB and perform the tinning process in a highly clean and controlled environment.

Factors to consider when selecting a PCB tinning process?

Factors to consider when selecting a PCB tinning process(1)
Factors to consider when selecting a PCB tinning process(1)

1.Always consider your requirements: After evaluating your requirements, your PCB maker will choose the most appropriate tinning method. You should tell your PCB maker what will be your PCB’s application, if it’ll go through high-temperature, etc.

2.Think about the production volume: There are some PCB tinning methods that are best suited during high production volume. Some slow processes are suited when the production volume is low.

3.Consider your product’s overall quality: The electroless nickel immersion gold process is one such process that’ll leave you with some world-class quality PCBs. Earlier, when the overall cost of PCB manufacturing was controlled, gadgets often used this method. But due to increasing costs and high inflation, most PCB makers have compromised with the quality to control their limited budget.

Key Takeaways

By now you must be clear with the PCB tinning and every detail related to it. After going through this article, you should be ready to start speaking to your PCB supplier about the tinning process like a pro. However, IBE Electronics is one such PCB maker that not only helps clients with the PCB tinning process, but also takes care of the entire hassle. You just have to contact IBE Electronics and IBE Electronics will make sure that you run into no trouble with the PCB tinning for your project.

FAQ

The electroplating method states that your PCB manufacturer will make a layer of tin on the PCB’s copper traces and copper pads. It’ll do so by dipping the PCB in an electrolyte solution. Then an electric current will be passed to the solution, which will ultimately enable the tin to settle on the copper surfaces.

  • Insufficient & Uneven Tinning
  • Too Much Tinning & Solder Bridging
  • Oxidation Or Contamination

1.Always consider your requirements
2.Think about the production volume
3.Consider your product’s overall quality

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