So far in life, many places will use the board to board connector, we are more familiar with it. We should how to choose better parameters of the board to board connector, as follows:
1. Pins and spacing
Pin number and pin spacing are the basic basis of connector selection. The number of pins you choose depends on the number of signals you want to connect. For some patch connectors, as shown in the figure below, the number of pins should not be excessive. Because in the process of SMT machine welding, due to the effect of high temperature, the connector plastic will be deformed by heat, middle uplift, resulting in pin virtual welding. Our P800Flash programmer used this kind of pin and bus to make the connection between plates in the early stage of development, and the result was that the pins of the prototype pin row had a large area of virtual welding. After replacing 2 pin rows with half the number of pins, there was no virtual welding.
Nowadays, electronic equipment is developing to miniaturization and precision, and the pin spacing of connectors is also from 2.54mm to 1.27mm and then to 0.5mm. The smaller the pin spacing, the higher the production process requirements. Pin spacing should depend on the company's production technology level, blind pursuit of small spacing.
2, electrical performance
The electrical properties of connectors mainly include: limit current, contact resistance, insulation resistance and electrical strength. When connecting a high-power power supply, pay attention to the limit current of the connector. When transmitting high-frequency signals, such as LVDS and PCIe signals, pay attention to the contact resistance. Connectors should have low and constant contact resistance, typically tens to hundreds of megohms.
3. Environmental performance
Connector environmental performance mainly includes: temperature resistance, humidity resistance, salt spray resistance, vibration, impact and so on. Select this parameter based on the specific application environment. If the application environment is humid, the connector has high requirements on moisture and salt spray resistance to avoid corrosion of metal contacts of the connector. In the field of industrial control, the resistance to vibration and impact performance of the connector is high, so as not to fall off the connector in the vibration process.
4. Mechanical properties
Mechanical properties of connectors include pulling and inserting force, mechanical anti-freeze, etc. Mechanical anti-freeze is very important to the connector, once inserted, it is likely to cause irreversible damage to the circuit!
Insertion force is divided into insertion force and separation force. There are upper limit of insertion force and lower limit of separation force in relevant standards. From the perspective of use, the insertion force should be small, and the separation force should be large. Too little separation force will reduce the reliability of contact. However, for connectors that often need to be plugged and removed, too much separation force will increase the difficulty of pulling out and reduce the mechanical life.
