electronic assembly services

PCB finishing processes are a common aspect of electronic assembly services. However, finishing processes vary and one of those processes is plating. In electronic assembly services, the plating process uses a chemical to fuse all of the different layers of the PCB together. PCB production knows four main types of plating: gold finger-plated plating, through-hole plating, reel linkage selective plating, and brushing plating. This article will discuss these four different methods in more detail.

1. Gold Finger Plating

Gold fingers are electroplated edge-connectors the are generally used to connect PCBs to a motherboard. Since gold fingers are mainly used for plugging, the gold thickness should be between 3u“ to 50u“. The expectant cycles of gold fingers are approximately 1,000 before any repair is needed, however, that is only if the correct thickness is used and if the gold fingers are applied correctly.

2. Through-Hole Plating

Through-hole plating is a crucial step in the manufacturing process for drilling. This method is beneficial as it allows both sides of the printed circuit board to be used and connect to other layers of the board. This method uses copper plating to allow electrical conductivity to travel through the board. The thicker the copper plating, the longer it can go through this thermal cycling without cracking. The life of the printed circuit board is dependant on the thickness of the copper plating of the through-hole.

Through-holes without the copper plating lack conductivity and electricity, and is unable to connect to the other side or other boards.

3. Selective Plating

Selective plating is the ultimate method for corrosion resistance and good contact resistance.  Selective plating is suitable for electronic components that use contact pins. The process of individually selecting the pins is extremely expensive so most electronic assembly services use batch welding. Selective plating only uses the portion of the metal copper foil plate that is selected, as the other part is coated with a resist film.

4. Brushing Plating

Brushing plating is also a form of selective plating. It is a plating technique that only uses a select amount of parts of electrolyte during the plating process, thus only a limited portion gets plated. This plating method is commonly used by electronic assembly services when repairing waste boards.

Defining Selective Soldering

In the world of electronic assembly services, one soldering process reigns supreme – selective soldering.

In the simplest of words, selective soldering is a way of soldering parts onto a printed circuit board in a fast and efficient amount of time, when compared to doing it by hand. It has become a go-to soldering method for many companies. In a more technical sense, selective soldering is an automated soldering process in that parts are soldered to a PCB in quick succession or all at once. In a sense, it sets up a template to make the process quicker.

Selective Soldering Processes

Laser Selective Soldering

– The laser is what makes this process different. It uses the laser to perform the process, thus making it a precision-intensive option.

Miniature Wave Select Solder Fountains

– Using a “wave,” the board is manipulated to solder in premeditated locations. You do not need the aperture tooling and masking for this method.

Selective Dip Solder Fountain

– Relying on the solder fountain, this process works on exact points where the board is meant to be soldered. Once the board is dipped into the fountains, soldering components are sought out and correctly soldered, while other parts remain untouched.

Aperture Tooling Over Wave Soldering

– The second “wave” process in which the board is pushed through a wave of solder which creates a molten solder pool. Un-soldered areas are masked for protection.

After any of these processes, the soldering machine is left to cool and the finished board continues through the manufacturing process.

Why Use a Selective Soldering System?

Because of its efficiency and accuracy, a selective soldering system has become the preferable way of soldering. Reflow ovens and hand soldering is still used and have their benefits, but mass production demands selective soldering. The question comes down to this – how many boards need to be produced, and will it be cost efficient for you to use a selective soldering system?

In conclusion, for many modern operations, selective soldering is the most efficient electronic assembly services for precision and speed. It does so without compromising the delicacy of the board. The companies that use them are able to create and deliver the products their customers seek out in the most effective way.