The main purpose of gold-plated circuit boards, the difference from other processes

2019-10-18 21:34:14 Juding Circuit Technology

There is a very common process used in the surface treatment of circuit boards, which is called the immersion gold process. In the production, the cost of the Shenjin board is relatively high, and the Jinjin process is not generally used. So how do we distinguish which PCB board needs to sink gold? Which circuit board does not need to sink gold? It can be analyzed and judged according to the following situations.

Analysis of main uses of Shenjin circuit board

1. The board has gold fingers to be gold-plated, but the layout other than the gold finger can be sprayed with tin or immersion gold according to the situation, which is the usual “sink gold + gold-plated finger” process and “spray tin + gold-plated finger” process, occasionally A few designers have chosen the full version of the immersion gold method to achieve the goal in order to save cost or time. However, Shen Jinda does not have the thickness of gold plating. If the gold finger is often inserted, it will cause poor connection.

2. The board's line width and pad spacing are insufficient. In this case, the tin-spraying process is often difficult to produce. Therefore, in order to use the immersion gold and other processes for the performance of the board, this is basically not the case.

3. Immersion gold or gold plating Because the surface of the pad has a layer of gold, the solderability is good and the board performance is stable. The disadvantage is that Shen Jin costs more than conventional tin spray, and it is usually more expensive if the gold thickness exceeds the PCB factory routine. Gold plating is more expensive, but the effect is very good.

 Understand the above three situations, you know the circumstances under which you need to make a sinking gold circuit board.

The immersion gold process is to deposit a nickel-gold coating with stable color, good brightness, smooth plating and good weldability on the surface of the printed circuit. What is the difference between the immersion gold process and other processes?

 The difference between PCB immersion gold process and other processes

1, heat dissipation comparison

The thermal conductivity of gold is good, and the pad made by it has the best heat dissipation due to its good thermal conductivity. The heat dissipation of the PCB board is low, the stability of the chip is stable, and the heat sinking of the gold plate is good. The comprehensive heat dissipation hole can be used on the CPU board and the BGA type component soldering base on the notebook board, while the OSP and the silver plate heat sink. Sexuality.

 2, welding strength comparison

After three high temperatures, the gold plate is full of solder joints. After three high temperatures, the bright OSP plate has a gray color, which is similar to the color of oxidation. After three high-temperature welding, it can be seen that the gold-plated solder joints are full and the light soldering is good and The activity of solder paste and flux does not affect, and the solder joints of the OSP process are dull and dull, affecting the activity of solder paste and flux, and are prone to air soldering and rework.

 3, electrical measurement comparison

The Shenjin board can be directly measured before and after production and shipment. The operation technology is simple and is not affected by other conditions. The OSP board is made of organic solderable film, and the organic solderable film is non-conductive film, so it cannot be directly measured. It must be measured before the OSP, but after the OSP, it is prone to excessive micro-etching and worry, resulting in poor soldering; the surface of the silver plate is generally stable, and the external environment is demanding.

 4. Process difficulty and cost comparison

The process of immersion gold technology is complicated, requires high equipment, strict environmental protection requirements, and is the highest in lead-free process cards due to the high cost of using gold elements. The process of chemical silver card is slightly less difficult, and the requirements for water quality and environment are quite high. Strict, the cost is slightly lower than the sinking gold plate; the OSP board is the simplest process, so the cost is also the lowest.

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