What Are Check Terminals?
Check terminals are terminal components processed to facilitate temporary wiring connections.
They are used for checking the operation of electronic components in circuit design or to check electrical characteristics in manufacturing processes. Probe-type terminals are commonly used for measuring instruments, such as oscilloscopes.
Since it is difficult to always hold a probe in one’s hand while conducting inspections, measurements are made by connecting it to a check terminal. Check terminals are also available in many shapes that are easy to apply probes to, reducing errors caused by human restraint.
They are sometimes referred to as checker chips or test terminals. In recent years, many RoHS-compliant products have also been sold.
Uses of Check Terminals
Check terminals are used to check board operation and electrical characteristics. The following is an example of where check terminals are used.
- Mounting on evaluation boards
- Signal extraction from logic circuits
Check terminals are used as a mounting base for direct connection to the board and are often mounted on the finished product.
Principle of Check Terminals
Check terminals are components that are placed in a circuit to expand the conduction area and facilitate measurement. Stainless steel or brass is used as the material, and the outside is plated with gold or brass over nickel. Operating temperatures range from -40°C to 150°C.
In many cases, colored beads are attached so that the color of the beads can be distinguished. The beads are made of glass or resin.
Types of Check Terminals
There is a wide range of types of check terminals, depending on the application. Shapes include the type that the probe is pressed against, the type that is hooked onto a loop, and the type that is fastened with an alligator clip.
Check terminals for logic circuits, which are suitable for logic circuits, can be attached to through-hole lands for top and bottom continuity. Check terminals for panels and signal checks are also available.
How to Select Check Terminals
Check terminals are sold by manufacturers specializing in peripheral accessories required when checking board operation, such as Mac-Eight. Check terminals are available for board mounting or surface mounting, and it is important to select the right one for your application.
Also, since there is a wide lineup of sizes and shapes, check terminals are selected according to the board space and the shape of the probe. Products that are not plated on the inside can be used for flow soldering, and the color of the beads can be differentiated for each signal line.
Other Information on Check Terminals
1. Check Terminal Blocks
Check Terminal Blocks are products with check terminals on the board as terminal blocks. Common parts, such as ground terminals and power supply terminals, are replaced with short bars, thus saving space and cost.
If check terminal blocks are not used, it takes time and effort to arrange multiple check terminals in a row, etc. Multiple tester terminals and alligator clips must also be used. By using check terminal blocks, work during inspections such as continuity and withstand voltage tests can be reduced.
Time can also be saved by using check terminal blocks during breakdowns and maintenance. It drastically reduces labour-hours spent on fabrication of electrical inspection jigs and inspection work.
2. How to Use a Check Terminal
Use a check terminal at the point where you want to check the voltage, etc., with a tester or oscilloscope. The check terminal should be soldered directly to the circuit, and a probe can be used to measure the voltage directly.
Generally, the check terminals are installed in the shortest distance from the point where you want to measure and in a position where they will not be affected by other circuits. Decide on the location of the check terminal at the time of circuit design. It is a good idea to avoid placing tall electronic components around check terminals, taking into account that probes may be applied to them.
Incorrect selection or placement of check terminals may have adverse effects such as increased wiring capacitance and influence of wiring impedance due to increased wiring length and wiring area. Reflected noise due to unnecessary radiation noise, etc., can result in erroneous measurements due to so-called wiring impedance matching or unbalanced shielding lines.