1. What is a board-to-board connector?

　　The basic concept of board-to-board connector is to connect different circuit boards together. It is the connector product with the strongest transmission capacity among all connector product types. It is mainly used in power systems, communication networks, financial manufacturing, Elevators, industrial automation, medical equipment, office equipment, home appliances, military manufacturing and other industries. At present, the main pitches of board-to-board connectors are 0.50mm, 0.60mm, 0.80mm, 1.00mm, 1.25mm, 1.50mm, 2.00mm, 2.50mm, 2.54mm, 3.96mm.

　　2. Classification and characteristics of board-to-board connectors

　　Board-to-board connectors are divided into different types according to the different connection methods between the circuit boards. Each type has its own characteristics. The following is an introduction to this aspect for you one by one:

　　First, pin header/pin header header and header header, also called power strip, are the cheapest and most common connection method. Application scenarios: low-end, large-size smart devices, development boards, debugging boards, etc. Advantages: cheap and convenient, hard connection is very stable, strong over-current capability, convenient for wire bonding and testing. Disadvantages: large size, difficult to bend, large spacing, difficult to connect hundreds of pins (too large).

　　Second, high-end board-to-board sockets are denser than pin headers, and are used a lot in compact products. Application scenarios: Basically all conventional smart hardware products are in use, and they are widely used. Advantages: large number of pins, small size, 1 cm length can do 40 feet (the same size of power strip can only do less than 20). Disadvantages: expensive, inaccessible frequently, and the structure design needs to be fixed.

　　Third, thickened board-to-board connector Board-to-board, board-to-wire, can be disassembled, combined, and can be inserted into the header. Usage scenarios: development boards, test boards, large and fixed devices (such as computer case wiring) Advantages: cheap, common, used with pin headers, very easy to connect and measure Disadvantages: bulky, not easy to fix, not suitable Mass production scenario.

　　Fourth, FPC connector plug/ZIF connector Many smart hardware devices need to pull out the signal from the motherboard. FPC is bendable, small in size, and changeable in shape. It is the best choice. Usage scenarios: the connection of the main board and the sub-board, the connection of the main board and peripherals, the need to bend the circuit, and the compact product space. Advantages: compact and cheap.

　　3. How to select the board-to-board connector?

　　It is very important for users to purchase board-to-board connector products correctly. So, how to choose a board-to-board connector, and what are the selection criteria? In recent years, the board-to-board connector is moving towards a smaller trend. The most common board-to-board connector pitch for handheld consumer electronic devices is 0.40 mm; while the stack height of 1.00 mm is a small connector, the connectors currently used by major original equipment manufacturers are as low as 0.70 mm, and sometimes even lower. Old-fashioned miniature connectors with a width of more than 4.00 mm a few years ago were replaced by connectors with a width of 3.40 mm. The current "narrow-body" board-to-board concept is usually in the range of 2.40 to 2.60 mm. Board-to-board products, is the smaller the better? When purchasing board-to-board connectors, in addition to basic issues such as circuit size, stack height and width, several things need to be considered:

　　Really the smaller the better? If you are willing to accept a smaller vacuum port pickup area, then maybe you are right. Before choosing a subminiature connector, you must check whether the connector has all the other properties you need, and carefully test it to ensure that it is strong and durable. Then, it seems necessary to choose a socket with a top-mounted connector, because this setup can run tracking under the socket and is likely to facilitate the use of conformal paint. Some disadvantages of top-mounted sockets are that the width of the vacuum pick-up area is often narrow. There is no plastic shell material above the socket terminals to prevent the rise caused by rough disconnection. The more uneven top surface of the socket may be a connection work belt for the operator Come trouble. These new connectors with greater disconnection sound great! Yes, but you may need to tolerate additional connector lengths in order to achieve the locking function required by these connectors; greater disconnection force usually also means greater engagement force, which may also be a larger size circuit Bring problems.

　　4. Board-to-board connector test and inspection method

　　1. Test and inspection of board-to-board connectors:

　　1) Observe that the loading voltage on the board-to-board connector should not exceed 50% of its rated voltage.

　　2) The installation size of the board-to-board connector For the plug-in header, the length of the soldering feet on the soldered PCB requires that the exposed part of the PCB board is greater than 0.5mm.

　　3) For board-to-board connectors with higher precision, try to choose models with a little positioning when the PCB space allows, so as to facilitate the operation when manual soldering is required.

　　4) Check if there is a foolproof design

　　5) Check whether the material used for the board-to-board connector contains lead.

　　6) Small size board-to-board connectors, low contact pressure, and low current and voltage applications, it is recommended to use gold-plated or silver-plated connectors to avoid the film resistance from affecting the signal.

　　7) Pay attention to observe the height of the board-to-board connector after mating, and whether it meets the soldering height of the components around the PCB. The mating height must be greater than the soldering height of the components around the PCB, and ensure that there is a certain margin to ensure that no interference occurs. Special attention should be paid to the possible height errors of the components after PCB soldering.

　　5. Board-to-board connection problems and common troubleshooting

　　The correct connection of the board-to-board connector products can increase the service life of the product and ensure the good operation of the mechanical equipment. Failure of board-to-board products and failure to deal with them in time will cause immeasurable economic losses. The following briefly introduces the connection and troubleshooting methods of the board-to-board connector circuit.

　　1) About the connection of the board-to-board connector

　　The board-to-board plug socket is used to electrically connect two separate circuit boards. It includes a first connector connected to the circuit board and an adapter connector used to connect the first connector in series, wherein the first connector It has a first terminal connected with the circuit board and a body containing the first terminal. The adapter connector is provided with a second terminal and a body accommodating the second terminal. The two extended tail ends of the second terminal can be plugged and matched with the first terminal to achieve and respectively set on the two circuit boards. The electrical conduction of the first connector, wherein the end of one of the first terminal and the second terminal is provided with a reverse bending elastic part, and the body and the second terminal can be set according to the standard of the spacing of the circuit board. Choose a moderate extension length.

　　2) About board-to-board connector troubleshooting

　　Once the product fails, the cause can be judged to be the wire breakage during use, the product loosening, etc. The frequency of wire breaking in the middle is not much, most of them are broken at the connector, so the focus of inspection should be on the sensor and the wires in the connection to see if they have loosening and poor contact. Generally, open circuit failures caused by poor contact are mostly caused by rust at the end of the product, and external dirt enters the terminals or connection sockets, resulting in a decrease in contact pressure. To deal with this kind of failure, the connector needs to be removed, then re-plugged, and its connection status can be changed to restore normal contact.