PCB News - Things you don’t know about gold plating and gold plating on PCB boards

Things you don’t know about gold plating and gold plating on PCB boards

1. PCB surface treatment

Surface treatment methods for printed circuits include: oxidation resistance, tin, lead-free, gold precipitation, tin, silver, hard gold plating, gold plating, gold plating, gold plating, palladium nickel, etc.

The main requirements are: low cost, good solderability, difficult storage conditions, short time, environmental protection technology, good welding, flat plate.

Tin powdering: Tin sputtering board is a high-precision multi-layer model (4-46 layers), adopted by many large communication companies, computers, medical equipment and aerospace equipment, as well as research units in China.

The golden finger is the connecting part between the storage bar and the storage slot. All signals are transmitted by golden fingers. The golden fingers are composed of many golden wires.

Because its surface is gold-plated, and the conductive contact refers to the finger, we call it "golden finger". The gold finger board must be plated or gold plated. However, because gold has high antioxidant activity and high conductivity, but due to the high price of gold, memory has now replaced gold.

Since the 1990s, tin materials have been popular. At present, the "golden fingers" of mother cards, memory and charts are almost entirely made of tin. Only the high-performance server/workstation part will continue to use the gold row method, which is naturally expensive.

2. The difference between gold plating and gold plating process The vault is chemically stored. A layer of gold deposits is produced in the chemical oxidation-reduction reaction method.

Generally speaking, the thickness of the deposit is thicker. It is a method of depositing nickel-gold deposits, which can provide thicker gold deposits. The electroplating of gold plating is based on the principle of electrolyte, which is also called electroplating.

Other surface treatments of metals are mainly electrolytes. In the process of applying actual products, 90% of the gold medal is a gold medal, because its low solderability is his fatal flaw, and it is also the reason why many companies abandon the golden process!

The gold deposition process has a stable nickel plating, good brightness, flat coating and good solderability on the surface of the printed circuit.

Fundamentally, it can be divided into four stages: pretreatment (degreasing, micro-corrosion, activation, after dipping), precipitation of nickel, precipitation, post-treatment (elimination of gold residues, drying, and drying).

The thickness of the gold mine varies from 0.0025 to 0.1Um. Due to high conductivity, oxidation resistance and long life, the circuit board is surface treated. Generally speaking, it is used as a keyboard, fingerboard, etc., and the basic difference between gold plating and shipwreck is gold plating (wear-resistant), while gold shipwreck is a soft gold (not wear-resistant) damage).

1. The vault is different from gold plating. The vault is much thicker than the gold coin. The gold deposit is the yellow color of gold, which is more yellow than the gold plating (this is a way of distinguishing gold and gold depository). The gold deposits are slightly white (the color of nickel).

2. The stored gold is different from the crystal structure formed by gold plating. Gold-plated gold is easier than gold-plated gold, and it will not cause bad solder. It is easier to control the voltage of the gold flakes being cast, and it is easier to handle the pasting of pasted products. At the same time, since gold deposition is more gentle than gold plating, gold deposition plates are not resistant to wear (pros and cons of gold medals).

3. Here only nickel and gold are transmitted in the photoelectric effect on the gold medal. The copper layer does not affect the signal.

4. Gold oil fields are higher than gold plating and are not easily oxidized.

5. With the increasing requirements for the processing accuracy of printed circuits, the line width and spacing reach less than 0.1 mm. Gold is placed on the short circuit. The gold-impregnated board contains only nickel and gold on the solder, so it is difficult to produce a gold wire short circuit.

6. Only gold bullion chips contain nickel and gold. Therefore, the combination of resistance welding and the copper layer in the circuit is stronger. If the project is compensated, it will not affect the spacing.

7. There are higher requirements for the plate. A vault is usually used, and the black pillow after assembly is impossible. The fineness and lifespan of gold foil is better than that of gold-plated gold foil.

3. Why use gold medals

With the integration of integrated circuits, the more the steps of integrated circuits, the higher their density. This vertical-level sputtering process is difficult to drag thin solder pads, which is difficult for SMT installation.

In addition, the storage time of tin sputtered boards is very short. This is a document that solves these problems.

1. In the surface mounting process, especially in the ultra-small surface mounting 0603-0402, because the softness of the buffer directly affects the quality of the solder printing process, and it plays a key role in the quality of reflow soldering. It is during the surfing installation process. Commonplace.

2. In the test phase, the influence of purchased parts and other factors does not mean that the license plate will be welded immediately, but it usually takes several weeks or even months before it is used. The plating time of plating is several times longer than that of lead alloys, so everyone is ready to use it.

In addition, during the sampling phase, the cost of PCBs or PCBs is almost the same as that of lead alloy plates. But as the wiring becomes denser and denser, the width and spacing reach 3-4 minutes.

Therefore, this causes the problem of short-circuit of the gold wire: as the signal frequency increases, the effect of the skin on the signal quality becomes more obvious. The skin effect refers to: high frequency alternating current, the current tends to concentrate on the surface of the yarn flow. According to calculations, the depth of the skin is related to frequency.

4. Why use a gold medal

In order to solve the above-mentioned problems of plated plates, printed circuit boards with plated plates have the following characteristics:

1. Due to the different crystalline structure between gold mines and gold mines, gold oilfields will be gold mines, which are yellower than gold-plated gold, and customers are more satisfied.

2. Due to the different crystalline structure between the vault and gold-plated gold, gold deposits are easier to weld than gold-plated gold, which will not cause welding problems, nor will it cause customer complaints.

3. Since only nickel and gold are located on the bottom plate of the gold block, the effect of the signal on the skin effect is that the copper layer will not affect the signal.

4. Since the precipitation of gold has a higher density than gold plating, it is not prone to oxidation.

5. Since only the welded parts contain nickel and gold on gold, it will not produce gold wires, which will cause slight shortening. Fifth, gold casting gold medals can be divided into two categories: one is gold, and the other is casting gold. During the gold plating process, the tin effect is greatly reduced, and the tin effect of gold mines is better.

2. Only on the issue of PCBs, there are the following reasons:

1. When printing on paper, there is a permeable film on the Pan drill bit, which may hinder the effect of tin, which can be verified by tin bleaching test.

2. If the wetting position of the Pan position meets the design requirements, that is to say, whether the design of the buffer can fully guarantee the supporting effect of the parts.

3. Whether it is contaminated or not, it can be obtained by ion contamination test. ipcb is a high-precision, high-quality PCB manufacturer, such as: isola 370hr PCB, high-frequency PCB, high-speed PCB, ic substrate, ic test board, impedance PCB, HDI PCB, Rigid-Flex PCB, buried blind PCB, advanced PCB, microwave PCB, telfon PCB and other ipcb are good at PCB manufacturing.