1.Introduction to Contact Pin

Contact pin is a common electronic component that is mainly used to connect signals or power sources in electronic devices to external circuits. It is usually made of metallic material which can be inserted into or plugged out from connectors. 

2.Classification of Contact Pin

Contact pins play a vital role in electronic devices. They build connections between circuit boards and transmit signals and power. Contact pin can also make circuit boards modular or replaceable, which facilitates maintenance and upgrading of electronic devices.Contact pins can be divided into various types according to different usages and structures, including:

(1) Straight contact pin: Straight pin is a common pin type whose pins are usually arranged in a straight line and can be inserted vertically into connectors on the circuit board.

(2) Pogo-pin: Pogo-pin is made of spring material and can maintain long term shape stability .

(3) Contact pin connector: Contact Pin Connector is usually used to connect multiple circuit boards or modules. They usually have holes which can be connected with other electronic components.

(4) SMD pin: SMD pin is only for surface mounted circuit board assembly to save space and reduce weight.

3.Coatings on Contact Pin Surface

Contact pin is used as a common method of connection in electronic components. Coating on its surface can improve electrical conductivity, corrosion resistance, oxidation resistance and other properties, so as to improve service life and performance. Commonly used coating materials include gold, silver, tin, etc.

(1)Gold coating

Gold coating is a treatment of plating gold on contact pin surface by electrochemical method, with excellent electrical conductivity and corrosion resistance. Meanwhile, golden color and brightness bring good appearance.

Therefore, in the field of high-end instruments or electronic components, gold plating is often used on contact pin surface.

(2)Silver coating

Silver coating is a treatment of plating silver directly on contact pin surface, with high electrical conductivity and corrosion resistance. Compared with gold coating, the surface gloss of the silver coating is weaker and not easy to oxidation. Therefore, in the fields of high-frequency and high-speed transmission, pins with silver coating has obvious advantages.

(3)Tin coating

Tin coating is a treatment of plating tin on contact pin surface. Common application scenarios include low frequency, low speed transmission and other fields. Silvery white color and excellent weldability of tin coating make it commonly used in applications like pin welding.

4.XRF in Contact Pin Coating Analysis

The thickness of coating is an important guarantee factor of contact pin quality. Detection of the pin coating is a critical step to ensure connector performance and reliability. Common coating thickness analysis methods include metallography, X-ray fluorescence(XRF), and electron microscopy. These methods can determine whether the coating thickness is within specified range. Among them, XRF analysis is one of the common and popular methods in the field of coating thickness analysis because of its non-destructive characteristic, rapidity and intuition.

5.Application Case

INSIGHT CTA(coating thickness analyzer) is easy to operate. Flexible configuration can cope with analysis challenges from contact pin samples of different types, shapes and sizes. Following are analysis results of a set of samples by INSIGHT. 

(1)Sample display

(2)Results