What Is a Test Socket?
A Test Socket is a tool used in the development process or pre-shipment inspection of electronic device packages and semiconductor device packages (hereinafter referred to as devices).
Designed to match the pinout of the package under test, it can be inserted into the socket to establish necessary connections and measurements. This allows for the rapid execution of device testing and development evaluation. The device insertion and removal are straightforward, enabling development evaluation and testing without soldering to the substrate.
The connection between the test socket and the device package is made using electrodes called probes. The mechanism involves the pins of the device package making contact with the probes, and establishing a circuit. The arrangement of probes varies between sockets, and various types are available for different applications.
Uses of Test Socket
The primary uses of test sockets include mass production testing and evaluation development testing of device packages.
Mass production testing is conducted to evaluate the operation and performance of devices and detect defects. The test socket, by inserting the device and making contact with the pins, serves as a tool for executing device testing. Using test sockets enables the efficient testing of a large number of ICs, allowing the identification of defective products. This process is a critical step in quality management, essential for ensuring the reliability of products.
Evaluation development testing involves performance testing when developing device packages. At the development stage, semiconductor chips are processed into their final packages. It is necessary to confirm whether the device operates correctly in this form and obtains the required characteristics at the development stage. Evaluation development is carried out using test sockets without directly implementing on the substrate, confirming characteristics and operations.
Evaluation Criteria for Device Packages
Both are used in testing device packages. Here are examples of items evaluated using test sockets during testing:
1. Pin Configuration Evaluation
Ensures that the pin configuration inside the package matches the design. It is also essential to check for any external damage to the package based on its appearance.
2. Electrical Characteristic Evaluation
Measures voltage, current, and frequency characteristics, and evaluates whether they are within specified values. Insulation resistance may also be measured and evaluated.
3. Mechanical Evaluation
Conducts mechanical evaluations such as the device’s impact resistance and the impact of vibrations.
4. Temperature Evaluation
For some applications, it is necessary to evaluate the temperature characteristics of the device. This is an example of applications used in automobiles or aircraft. Using a test socket, the device’s operation is tested in high-temperature environments.
Principles of Test Socket
The principle of the test socket focuses on facilitating the connection and testing of electronic devices and ICs. The test socket is designed to correspond to the pinout information of a specific IC or device, and the contacts of the test socket are arranged based on the pinout information of the IC. This establishes a connection between each pin of the IC and the test socket.
Designed for easy insertion and removal of the device under test for testing purposes, it allows different devices to be tested using the same test socket, enabling quick testing and debugging. It plays a role in transmitting signals at each pin, connecting the internal signals of the device to external test equipment.
Some products can be customized to accommodate different ICs or semiconductor devices. This may involve changing the pinout to match a specific IC package or adjusting the design to meet special requirements.
Types of Test Sockets
Test sockets come in various types depending on the contact method. Here are some examples of types of test sockets:
1. Probe Pin Type
These are probes with a structure that holds a spring inside a barrel (pipe) and allows the plunger to operate (stroke) vertically by tilting it inside the barrel. They are also called Pogo pins or spring probes. Probe pins are generally categorized into two types: double-ended movable type and single-ended movable type. Additionally, there are variations such as internal spring type and external spring type, depending on how the spring is implemented.
2. Leaf Spring Type
Manufactured by different companies with unique structures, they generally use the elasticity of metal springs or rubber to achieve the stroke required for probing.