The PCB factory analyses the difference between gold plate and gold plate

In the actual trial process, 90% of the gold plate can be replaced by gold-plated plate. The poor weldability of gold-plated plate is its fatal deficiency, which is also the direct reason for Jialichuang to give up gold-plated plate! In the process of use, because the electrical conductivity of gold is small and widely used in the contact road, such as keyplate, gold finger plate, gold plate to sink the most fundamental difference is that gold is hard gold, gold is soft gold, from the electrical performance analysis!

First, the difference between gold plate and gold plate

Two, why use gold plate

As the integration of IC becomes higher and higher, the IC feet are more and more dense. The vertical tin-spraying process is difficult to flatten the thin pad, which brings difficulties to SMT mounting. In addition, the shelf life of the tin spray plate is very short. And the gold-plated plate is good to solve these problems: 1 for the surface mounting process, especially for 0603 and 0402 ultra-small table paste, because the flatness of the welding pad is directly related to the quality of the solder paste printing process, and plays a decisive influence on the quality of the reflow welding behind, so the whole plate gold-plated in high density and ultra-small table paste process often see. 2 In the trial production stage, affected by components procurement and other factors are often not the board to weld immediately, but often have to wait for a few weeks or even a month to use, the shelf life of the gilded plate is better than that of the lead tin

Gold is many times longer so everyone is happy to use it. Moreover, the cost of gold-plated PCB at the sampling stage is almost the same as that of lead-tin alloy plate.

But with more and more dense wiring, line width, spacing has reached 3-4MIL. Thus brings the problem of short circuit of gold wire:

With the increasing frequency of signals, the impact of signal transmission in multiple coatings caused by skin effect on signal quality becomes more obvious:

Skin effect refers to: high frequency alternating current, current will tend to concentrate on the surface of the wire flow.

According to the calculation, skin depth is related to frequency:

The other disadvantages of gold plate are listed in the table of differences between gold plate and gold plate.

Three, why the use of gold plate

In order to solve the above problems of gold-plated plate, the use of gold-plated PCB has the following characteristics:

1. Because of the different crystal structure formed by sinking gold and gold plating, sinking gold will be more yellow than gold plating, and customers are more satisfied.

2, because the crystal structure formed by gold plating and gold plating is different, gold plating is easier to weld, will not cause poor welding, cause customer complaints.

3, because the gold plate only has nickel gold on the pad, the signal transmission in the skin effect is in the copper layer will not affect the signal.

4. Because of the denser crystal structure of gold plating, it is not easy to produce oxidation.

5, because the gold plate only has nickel gold on the pad, so it will not be produced into gold wire caused by short.

6, because the gold plate only has nickel gold on the welding plate, so the welding on the line and the combination of copper layer is more firm.

7, the project will not affect the spacing when making compensation.

8, because of the gold and gold plating formed by the crystal structure is not the same, the stress of the gold plate is easier to control, for the products of the state, more conducive to the processing of the state. At the same time, because the gold is softer than the gold, so the gold plate is not wear-resistant gold finger.

9. The flatness and service life of the gold plate are as good as that of the gold plate.

Automotive sensor PCB function and performance requirements

Automobile sensor as an important component of automobile electronic computer control system, its use quantity and technical performance, directly affect the working condition of automobile electronic control system. Ordinary cars are equipped with dozens of sensors, while the number of sensors in luxury cars can reach more than 200. These sensors are mainly distributed in the major systems of the car. The more developed the automobile electronization, the higher the degree of intelligence, the greater the dependence on the sensor, therefore, the sensor is one of the core contents in the field of automotive electronic technology research.

A sensor is a device or device that can feel the specified measured signal and convert it into a usable signal according to a certain law. It is usually composed of a sensor and a conversion element. It can transform information such as physical quantity, electric quantity and chemical quantity into electrical signal which can be understood by computer. This transformation includes the transformation of energy form, so it is also called transducer. Automobile sensor is installed on the automobile, used to sense the changes in the process of driving. Automobile sensor is the input device of automobile computer system. It converts the information of various working conditions in automobile operation, such as speed, temperature of various media, engine operation conditions, etc. into electrical signals to computer, so that the automobile is in the best working state. 

The accuracy and reliability of the sensor are two very important parameters for the automobile. Generally speaking, the performance of the vehicle sensor mainly has the following requirements:

First: high precision requirements

For vehicle sensor accuracy requirements of 1% or less, requirements in the range of -40 ~ +120°C can work for a long time, vibration resistance is 150 ~ 2000Hz, impact resistance can reach from 1m height fall on the concrete without causing a decline in accuracy, and can resist electromagnetic interference, corrosion resistance.

Second: strong environmental adaptability

The use of the car environment is very bad, from the engine generated heat, vibration, gasoline or diesel vapor, as well as tire sludge, splashing water, can be summarized as temperature, humidity and other climatic conditions, vibration impact and other mechanical conditions, power supply, electromagnetic interference and other electrical conditions, or simply summed up as temperature, humidity, vibration and other physical environment, Overvoltage electromagnetic wave and other electrical environment. Different environments require different sensors.

Third: good stability

Car traffic accidents and people's lives are closely related, so car sensors have high reliability requirements, in addition, the country has strict regulations on the automobile exhaust components, such as the content of CO, NOx and other components, in normal circumstances to meet the standard, but also required to complete the prescribed driving distance, still can reach the exhaust standards.