The electronic equipment must be interconnected according to the circuit schematic diagram to achieve the predetermined function. If the connection is wrong, the whole circuit board will be invalid. Therefore, the connection with the best compatibility of reliability, process and economy is an important part of the circuit board design. One. There are many ways to connect externally. It is flexible to choose according to different characteristics. The following two methods are the most common.

Welding method

The advantage of this method is that the operation is simple, the cost is low, the reliability is high, and the fault caused by poor contact can be avoided; the disadvantage is that the interchange and the maintenance are not convenient enough. This method is generally applicable to the case where the component has fewer external leads.

1, PCB wire welding

No connectors are required, as long as the wires are used to directly solder the external connection points on the board to the components or other components outside the board.

Pay attention to the interconnection of the board when soldering:

(1) The pads of the soldered wires should be as close as possible to the edge of the board and arranged in a uniform size to facilitate soldering and maintenance.

(2) In order to improve the mechanical strength of the wire connection and avoid the wire or the printed wire being pulled off due to the pulling of the wire, the hole should be drilled near the solder joint on the circuit board, and the wire should pass through the welding surface of the printed board. Holes are then inserted into the pad holes from the component faces for soldering.

(3) Arrange or bundle the wires neatly and fix them with the plate by wire cards or other fasteners to prevent the wires from breaking due to movement.

2, PCB cable welding

The two circuit boards are connected by a cable, which is reliable and difficult to connect, and the relative positions of the two boards are not limited.

Direct soldering between printed boards, this method is often used for a 90 degree angle between two printed boards, which becomes a whole circuit board component after connection.

Connector connection

In more complicated instruments and equipment, the connector connection method is often used. This “building block” structure not only ensures the quality of the mass production of the product, reduces the cost of the system, and provides convenience for debugging and maintenance. When the equipment fails, the maintenance personnel do not have to check the component level (that is, check the cause of the failure, trace the source to the specific components. This work takes a considerable amount of time), as long as it is determined which board is not normal, It can be replaced immediately, troubleshooting in the shortest time, reducing downtime and increasing equipment utilization. The replaced circuit board can be repaired in a sufficient amount of time and used as a spare part after repair.

1, printed board socket

This type of connection is often used in more complex instruments. In this way, the printed plug is made from the edge of the board, and the plug part is designed according to the size of the socket, the number of contacts, the distance of the contact, the position of the positioning hole, etc., so as to match the dedicated circuit board socket.

When making the board, the plug part needs to be gold-plated to improve wear resistance and reduce contact resistance. This method is simple to assemble, interchangeable, and has good maintenance performance, and is suitable for standardized mass production. The disadvantage is that the cost of the printed board is improved, the manufacturing precision and process requirements of the printed board are high; the reliability is slightly poor, often due to poor contact of the plug portion. In order to improve the reliability of the external connection, the same lead wire is often taken in parallel through the contacts on the same side or both sides of the circuit board.

2, standard pin connection

This method can be used for the external connection of the printed board, especially in small instruments. The two printed boards are connected by standard pins, which are generally parallel or perpendicular, making mass production easy.