Episode 5:Smartphones and tablet devices

There are new models of smartphone and tablet announced and launched almost every day.

You have probably guessed from the contents so far that there is a deep relationship between plating and these information terminals, which are displaying some of the most striking technological innovation of today.

From this episode onwards, I will be talking about more specific examples and in particular will be examining plating on parts that are not visible from the external appearance of items.

Let’s have a look at what’s inside a smartphone!!

Many functions packed tightly in a limited space

The smartphone is a very familiar device to us all, but there are probably very few people who have had a look inside one. Please click on the video to see.

When we look inside a smartphone, it is clear that the battery takes up a lot of the space. Even though there have been advances in power saving, the ever higher functionality of the smartphones means that they consume a lot of electricity and this large battery size is unavoidable. Compared with this, don’t you think that the other components are smaller than you imagined? Progress in weight reduction and space saving has meant that all of the components are becoming very compact. Tablet devices are also made with roughly the same configuration as smartphones.

Plating has played a very large role in making it possible to tightly pack functions into such a small space in this way. Plating is used a lot on parts such as the wiring and electronic component connections. The electronic components themselves are also produced using plating technology.

The board that integrates all of the control – The main board

Holding the various related components (parts)

The most conspicuous of the contents of a smartphone or tablet device is the main board. All of the control components, electronic components and units are connected and controlled on this board. If you examine this board closely, you will no doubt see that there are something like fine lines (brown lines) on it. These brown lines are called the copper wiring. They are something like electrical cables and are made using copper plating. They all fulfill the role of electrical wiring.

As miniaturization and higher functionality proceed, the width of the wiring and also the space between the wiring must be reduced. It is therefore necessary for this copper wiring to become more precise. In other words, it is necessary to have more precise plating technology.

The core for information processing – CPU

This is truly the brains of the smartphone

If you ever see a product explanation for a smartphone or tablet device, it will always have “CPU: ***** ** Hz” written in it. Many people will use this as a criterion for purchasing a device.

This CPU (Central Processing Unit) also contains many parts where plating is used. The main area of this use is in the wiring (circuit formation) inside the CPU. The wiring inside a CPU is extremely precise and it is necessary to produce wiring at a level that is not visible to the naked eye. The manufacturing methods used require very advanced technologies.

Also, the core part of the CPU (the central part where the circuits are) is made using a piece of silicon and the circuits are formed on top of the silicon. Plating technology is also used in the connections between the circuits on that silicon part and other parts such as the main board.

Plating is in action in many other parts too!

In addition to the uses written above, plating is also used on many other parts of smartphones and tablet devices and plays various different roles. Here I will introduce one example of this.

The contact points for external devices: Connectors

A connector is a point for the insertion of cables for data exchange with external devices. As this involves an exchange of electrical signals, it is essential that the electrical conduction is reliable. Furthermore, as the cables are constantly being inserted and removed, the connector is also required to be durable. Various types of plating are used for the various different types, shapes and applications of the connectors. In some cases, the aesthetic appearance is also considered and gold plating is used.

Essential parts for circuits: Chip resistors and chip capacitors

If we examine a board from above, we can see that there are rows of multiple square objects that look like small pillows. In many cases, these will be the chip resistors and chip capacitors.
These are essential components that are used for the adjustment and rectification of the electric current on the board.
The color is different at the ends and these parts are the electrical contacts. These are used for the connection to a circuit, such as on a printed circuit board. These parts are produced using plating.
As devices become ever smaller, some chip resistors and chip capacitors are now even smaller than 1 mm. The plating for these is performed on machinery designed to produce specialist plating.

Plating model introduction (PWB/PKG)

As I have said before, plating can be used to give various different items new functions and performance and new applications. Here I will introduce items produced using various types of plating in models that will make the flow of the production more easy to understand.
In this episode, a model has been produced of PWB/PKG manufacturing.

Wiring production processes

[1] Produce the foundation (Electroless copper plating)
The wiring is produced using electrolytic copper and metal is necessary in order to conduct the electricity.
For this reason, the first step is to perform electroless copper plating as a foundation.

[2] Produce the wiring (Electrolytic copper plating)
The wiring is produced on the foundation using electrolytic copper plating.

Final surface treatment

[3] Produce a barrier layer (Electroless nickel plating)
This is used to prevent the diffusion that occurs when gold is plated directly onto the surface of copper plating and also to realize plating strength.

[4] Produce an anti-corrosion layer (Electroless gold plating [Flash gold plating])
If an oxide layer is formed on the surface, then the connection with other electronic components becomes more difficult. The final stage is therefore to perform gold plating on the surface to prevent oxidation. The gold plating used is an extremely thin layer. [Flash gold plating]

*PWB: Printed Wired Board/PKG: Package – a general term indicating electronic components.

Smartphones and plating reliability

Smartphones have become an essential tool for our daily lives and it is easy to see how their reliability is an important issue. It is a device that can be carried around, so it is often subjected to impacts when it is dropped or bumped against something. If these impacts were to cause the electronic components to come loose or the wiring to break, then the smartphone would instantly become unusable.

The large amount of plating technology used inside smartphones has also been selected for its reliability.