Differences between e-gold and sinking gold and Some Problems

Gold sinking board vs Gold plating board

I. Differences between gold sinking board and gold plating board

1. Differences in principles

Flash gold adopts the chemical deposition method!

Planting gold adopts the principle of electrolysis!

2. Differences in appearance

The electric gold will have an electric gold lead, but the chemical gold will not. In addition, if the requirements for gold thickness are not high, the method of gold conversion is adopted,

For example, a memory PCB uses a gold-Based Method on its pad surface.

And tab (Golden finger) has the use of electricity and also has the use of gold!

3. Production Process differences

Gold Plating, like other electroplating, requires power-on, and requires a rectifier. there are many kinds of processes, including cyanide, non-cyanide, non-cyanide, citric acid, and sulfate. non-cyanide systems used in the PCB industry.

Gold (gold plating) is deposited on the plate by chemical reaction in the solution without power-on. they have their own advantages and disadvantages. In addition to power-on and power-off, the power supply can be very thick, as long as the time is extended, suitable for bonding boards. the chances of e-gold potion waste are smaller than that of gold. however, the electric Fund requires full-board conduction, and is not suitable for very small lines. gold is usually very thin (less than 0.2 microns), the purity of gold is low. work fluid can only be discarded to a certain extent

The circuit board of a gold board has the following features:

1. the scalability of the gold board is equivalent to that of the OSP, and the wetting of the dip tin board of the gold board is the best for all PCB finishing.

2. The thickness of electric gold is much higher than that of chemical gold, but the flatness is not as good as gold.

3. The electric gold is mainly used for gold fingers (wear-resistant), and there are also many pad.

The circuit board of the gold sinking Board has the following features:

1. The gold sinking board is golden yellow, and the customer is more satisfied.

2. The gold sinking board is easier to weld and will not cause complaints from customers due to poor welding.

3. the sinking gold plate only has nickel gold on the pad, and the signal quality is not affected by the signal transmission in the copper layer.

Ii. Why should we use gold plating plate?

As the integration of IC becomes higher and higher, the more IC feet become more and more confidential. The vertical tin spraying process is difficult to flat the welding pad, which makes it difficult to mount Smt. In addition, the waiting life of the tin spraying Board (shelf life) is very short. The plating plate solves these problems:

1. For the surface mount process, especially for the 0603 and 0402 super small table stickers, because the Solder Pad flatness is directly related to the quality of the solder paste printing process, it has a decisive impact on the quality of the subsequent re-flow welding, the whole plate is often seen in high-density and ultra-small table stickers.
2. In the trial phase, Components Procurement and other factors often do not affect the welding of boards right away, but often wait a few weeks or even months before they are used. The waiting life of gold plated boards (shelf life) it is much longer than lead-tin alloy, so we are happy to use it. In addition, the cost of the gold-plated PCB in the sampling phase is almost the same as that of the lead-tin alloy board.

However, as the wiring becomes more and more dense, the line width and spacing have reached 3-4 mil, which leads to the problem of Kingdom short circuit;

As the signal frequency increases, the skin effect significantly affects the signal quality when the signal is transmitted in multiple coatings;

Skin effect refers to the high-frequency alternating current, which tends to flow on the surface of the wire.

Iii. Why should we use gold sinks?

 

To solve the above problems of gold plating board, the PCB adopting gold sinking Board has the following features:

1. Because of the different crystal structures formed by gold sinking and gold plating, the gold sinking is yellow compared with gold plating, and the customer is more satisfied.

2. Because of the different crystal structures formed by gold sinking and gold plating, gold sinking is easier to weld than gold plating, which will not cause poor welding and cause complaints from customers.

3. Because the sinking gold plate only has nickel gold on the pad, the signal quality is not affected when the signal is transmitted in the copper layer.

4. The crystal structure is more dense and hard to produce oxidation because the gold sink is stronger than the gold plating.

5. Because the gold sinking board only has nickel gold on the pad, it will not be made into gold wire, resulting in micro-short.

6. Because the gold sinking board only has nickel gold on the pad, the solder resistance on the line is more powerful with the copper layer.

7. The gap will not be affected when the project is compensated.

8. Because of the different crystal structures formed by gold sinking and gold plating, the stress of the gold sinking board is easier to control. For products with fixed state, it is more conducive to the processing of gold sinking. At the same time, it is because the gold is more soft than the gold plating, so the gold plate is not wear-resistant.

9. the smoothness of the gold sinking board is as good as the service life of the gold plating board.

Iv. Advantages and Disadvantages of gold, gold plating and gold immersion

The three are different. Chemical gold is also called chemical gold. A layer of coating is formed by chemical oxidation and reduction reaction. Generally, the thickness of the coating is thick. It is a kind of method for depositing the Gold Layer of Chemical Nickel gold to reach a thick gold layer; another kind is the replacement gold, that is, the leaching gold, that is, the replacement gold, the general thickness is thin, 1-4 micro-Inches about the gold plating is generally only gold plating, can be plated thick; one half of the deposit and leaching gold are used for boards with relatively high requirements. The flatness is better, and the deposit is better than the leaching gold. The deposit generally does not appear as a black pad after assembly; because of the high purity of the plating layer, the solder joint strength is higher than the above two.

V. Q &

1. What are the abbreviations of gold and gold plating?

Answer: A. Electroless gold without Electrolytic gold leaching gold Immersion Gold (IG) Chemical gold nickel oxide-less nickel (en)]

B. Electrolytic gold soft (bondable) Gold Hard Gold

2. How can nickel be used on copper (whether chemical reduction is also used )? Gold and copper cannot be bonded, So nickel is required, right?

A: When the temperature is high, the interaction between gold and copper passes through the nickel layer, causing migration and increasing contact resistance, which is not good for the golden finger. Nickel blocks both migration and diffusion between gold and copper. Therefore, it is called diffusion layer or barrier metal. Nickel Plating before gold plating, minimum thickness U ".

3. Our supervisor said that if we want to hard-Plated Gold on the key pad (like the keypad of a mobile phone), can we make some hard-Plated Gold? Are others normal?

A: The keypad provides hard and golden touch resistance for contacts.

4. Is hard or soft gold plating a processing process?

If they use gold, gold dip, or gold plating soft gold, are they used only in wirebond hard gold and only in the Gold finger? Thank you! Hard Gold soft gold is Electrolytic gold in the process, as long as it is pluggable, touch-resistant hard gold, such as the Gold finger card board, keypad, Calculator board, etc. however, to wire bonding, the soft gold is used to obtain the high-purity gold plating. there is no Electrolytic gold process in the gold leaching metal. Because of its thin nature, the "gold leaching" is usually used to replace tin spraying. It is recommended that its surface be flat and has advantages in assembly. Lead-free is also one of the requirements. the gold is thick and can replace the folding Plating Without Farah Guide wires in the Electrolytic gold process. some people use the gold wire (usually aluminum wire), but the chemical en and P content 6-10 affect the hardness, wire bond bottom metal should be hard enough, otherwise, the high temperature may cause wedge bond (when the TG is exceeded), and the combination strength cannot pass.

5. Why is the copper thickness of the mobile phone board top bot (1 oz) different from that of the inner (0.5 oz?

This is an electrical design consideration. The inner layer is 05. Oz. refers to the sending of materials. The outer layer usually refers to the finished thickness, so if it is finished, if it is 1 oz. The sending material may be 05. Oz. After plating, it is changed to 1 oz.

Differences between e-gold and sinking gold and Some Problems