Internal connector for smart hardware products, circuit board connector selection!

January 24, 2023

Connectors that connect different circuit boards together. Whether it is a mobile phone or a smart hardware device, a large number of connectors are used.

As a hardware engineer, you need to be familiar with the characteristics of various connectors and be able to properly plan what kind of connectors to use. The main categories and characteristics are as follows:

(This article focuses on internal connectors for smart hardware products and does not involve external connections.)

Board-to-board connector

Pin row mother / pin

Pins and rows of mothers, also known as rows and rows, are the cheapest and most common connections.

Application scenarios: low-end, large-size smart devices, development boards, debug boards, etc.

Advantages: cheap, convenient, hard connection is very stable, strong over-current capability, convenient wire bonding and testing.

Disadvantages: bulky, difficult to bend, large spacing, it is difficult to do hundreds of pin connections (too big).

Ordinary 2.54mm pitch row plug

Some high-end board-to-board sockets

Board to board socket

More dense than pin headers, used in a lot of compact products.

Application scenario: Common smart hardware products are in use. Very widely used.

Advantages: A large number of pins, small size, can make 40 feet with a length of 1 cm (the same size of a row can only do less than 20).

Disadvantages: expensive, can not always plug, structural design needs to be fixed.

Common board to board connector

Widely used board-to-board connector for mobile phones

Multi-pin board-to-board connector

Thick-type board-to-board connector

Board-to-line

DuPont Line

Hardware engineers have been using the company from the school, can be disassembled, can be combined, and can be inserted into the pin header.

Use scenario: development board, test board, large and fixed equipment (such as computer chassis wiring)

Advantages: cheap, common, with pin headers, very easy to connect and measure

Disadvantages: bulky, not fixed, not suitable for mass production scenarios.

Cable socket

Similar to the DuPont line, but the plug is customizable and can be snapped onto the socket without loosening.

For production-grade products, cable outlets are usually used instead of the Dupont cable.

Wiring harness

For rotatable products, such as laptop hinges, robot arms, etc., harness connectors are required. More sophisticated than the above cable sockets, the number of lines is more, but it is more expensive than 10 times.

FPC plug/ZIF connector

Many smart hardware devices need to pull the signal out of the motherboard. FPC is flexible, small and varied in shape.

Usage scenario: connection between main board and sub board, connection between main board and peripherals, bent lines, and compact product space.

Advantages: both compact and cheap.

Disadvantages: small over-current, connection reliability is not as strong as the board-to-board socket. In the structural design, the connector cover needs to be pressed well, and it is best to fix the adhesive tape securely.

(About the cheap: The board-to-board socket needs two male and female seats, and the ZIF connector only needs one, so the ZIF is half cheaper than the board-to-board.)

Stamp hole welding

As the name suggests, a circle around the circuit board is welded and soldered directly to another circuit board. The half hole looks like a hole on the edge of a stamp, so it is called a stamp hole.

Application scenario: Connection between module board and main board, heightening of local components

Advantages: Cheap, convenient, direct hard connection is strong enough.

Disadvantages: The number of pins can not be too much, the structure space can only be placed overlapping.

2G module stamp hole.

iPhone X uses a PCB board instead of connector

IPhone X show technology, with a thick PCB board, the two boards overlap. It is an advanced stamp hole craft. More pins than the connector, shorter connection distances (better signal integrity), greater immunity to EMI and ESD. In addition to being difficult to produce and difficult to repair, other properties are good.

Slots

There are a lot of slots on the computer motherboard, memory, graphics, SSD, but on the smart hardware, there are very few slots.

Some communication modules use mini PCI-E slots for laptops. Smart hardware communication modules, sometimes with mini PCI-E, are also available. (But most are stamp hole or board-to-board connectors)