Is there any difference between gold plating and silver plating on PCB?

Lots of DIY specialists will discover that there are various color of PCB in market.Black, green, blue, yellow, purple, red, and brown are the common ones. Some gold plating pcb manufacturers even prefer white and pink,some other colors which haven’t be used .

In the traditional impression, black PCB seems to be positioned at the high end, while red, yellow are dedicated to the low end. Is that right?

The gold plating PCB without soldering mask is easily oxidized when it exposed to air.

We know that both sides of gold plating PCB are copper plated. In the process of PCB production, whether the copper layer is made by addition method or subtraction method, it will eventually be a smooth and unprotected surface. Although the chemical properties of copper are not as active as aluminum, iron and magnesium, pure copper is easily oxidized in contact with oxygen in the presence of water.  The surface of pure copper will be oxidized soon after it comes into contact with the air,as there is oxygen and water vapor in the air.The copper in PCB is very thin, it will be  a poor conductor of electricity after oxidized, which will greatly damage the electrical performance of the whole PCB.

To prevent copper oxidation, to separate the soldering and non-soldering parts of the gold plating PCB during soldering, and to protect the PCB surface, engineers developed a special coating. This coating can be easily applied to gold plating PCB surface, forming a protective layer with a certain thickness and blocking the contact between copper and air. This coating is called a soldering layer and is made of a soldering varnish.

Since it's called lacquer, there must be different colors. Original solder block paint can be colorless and transparent, but usually there are many tiny letters printed on the board for the convenience of maintenance and manufacturing. Transparent soldering paint can only reveal the PCB background color, whether manufacturing, maintenance or sales, the appearance is not good enough. Therefore the engineers added a variety of colors to the solder resist paint, resulting in black, red or blue PCB.

The wiring on the gold plating PCB is not easy to be seen when it is black, which brings difficulties for maintenance.

From this point of view, there is not any relationship between PCB color and quality . The only difference is that the color of end plated. It will not have any impact on the performance, nor will it have any impact on the heat dissipation if the design and manufacturing process are exactly same.

As for the black PCB, its surface wiring is almost completely covered, resulting in great difficulty in the later maintenance, so it is not a good color for PCB manufacturer. In recent years, people gradually prefer to use dark green, dark brown, dark blue and other solder resistance paint for the purpose of maintenance.

At this point, we have know more about the color of PCB. The reason why there is a saying that "color represents high or low grade" that manufacturers used to make high-end PCB black,to make low-end products blue, green, yellow.In a word, products give meaning to colors, not colors give meaning to products.

What are the advantages of gold, silver and other precious metals used in PCB?

Let's turn to talk about the precious metal on the PCB! Some manufacturers in the promotion of their products, they will specifically mention that their products used gold immersion, silver immersion and other special processes.So what's the use of this process?

There are a part of the copper exposed to the surface for the purpose of soldering.It is called solder pad which are usually small rectangular or circular. In the above, we know that copper used in PCB is easily oxidized, so only the copper on the solder pad is exposed to air after the solder block paint.

When the copper on the pad is oxidized,it not only increases the difficulty of welding, but also increases resistivity.It will affect the final product performance seriously. So engineers came up with all sorts of ways to protect the pads. For example, an inert metal is plated with gold, or a layer of silver is covered by a chemical process on the surface, or a special chemical film is used to cover the copper layer to prevent the welding disc from contacting the air.

PCB exposed on the welding disk, copper layer directly exposed outside. This part needs to be protected and prevented from being oxidized. From this perspective, whether it is gold or silver, the purpose of the process itself is to prevent being oxidized and protect the welding plate so as to ensure the yield of the product in the subsequent welding process.

Different metal they used with different storage time and environment of PCB. Therefore, PCB factory will package the PCB through vacuum plastic sealing machine before delivery,so that it can protect PCB from damage.

Before assembling the components on the machine welding, these boards should be checked again, oxidized gold plating PCB will be removed. Those boards that delivered to our clients have passed all sorts of detection.Even oxidized for long time,it won’t affect the solder dish and soldered component because the oxidation just happened in plug and unplug connection place.

The resistance of silver and gold is lower. Will it reduce the heating power after coated with gold or silver?

As we know, resistance effect calorific value most. It is related to the material of the conductor, the cross-sectional area and the length of the conductor.The thickness of metal material on the surface of the welding plate is even much lower than 0.01 mm. If the welding plate is processed by OST(organic protective film), there will be no excess thickness at all.The resistance shown such a small thickness is almost zero, and even cannot be calculated. Of course, it will not affect the calorific value.