Electricity, a part of our lives through devices like television, refrigerators and lighting, is not seen and has no smell. Electricity is created by electrons that move around freely inside substances (free electrons). Objects that electrons can move around easily in are called “conductors” and objects that are difficult for electrons to move in because they are bound tightly to atoms are called “insulators”
Current is the flow of electricity. (Unit: Amps A)
Voltage is the power when electricity is running. (Unit: Volt V)
Resistance is the force obstructing electricity flow. (Unit: Ohm Ω)
These are often described using the flow of a river as an example.
Ohm’s law describes the relationship between current, voltage and resistance.
Current=Voltage÷Resistance
Current increases when voltage increases and decreases when resistance increases.
Voltage=Current×Resistance
Voltage increases when current or resistance increases.
Resistance=Voltage÷Current
Resistance increases when voltage increases and decreases when current increases.
There are two directional flows of electricity, direct current and alternating current.
Direct current (DC) is the flow of electricity in which the magnitude (current) and strength (voltage) of electricity are almost constant and the flow of electricity have both a positive and negative pole.
Flashlights with batteries use direct current. If the battery is inserted with the positive and negative poles reversed electricity does not flow and the flashlight does not light up.
On the other hand, for alternating current (AC) the positive and negative poles can alternate and the current and voltage also change periodically. Electrical outlets in houses use alternate current which is why outlets can be used without worry about the direction of insertion. Most household appliances can be used with an outlet but since it is easier to use direct current due to the constant current and voltage, the alternating current is changed to a direct current inside the appliance.
Connectors are mechanical parts that connect electricity. Devices can be connected and the inside of devices can be wired with boards or cables.
● Without connectors
Each time a cable is cut it will need to be connected by soldering, etc. which is very difficult
● With connectors
Can easily connect and disconnect to electricity
There are various types of connectors but let’s take a look at a USB connector (Type-C) that everyone is familiar with.
The connector on the cable side is called a “plug” and the connector on the device side is called a “receptacle”. By connecting the plug and receptacle electricity can flow.
Other than Wire-to-Board connectors like the USB connector...
● there are connectors
connecting Board-to-Board...
● and there are also connectors
connecting Wire-to-Wire.
Connectors perform the role of connecting devices in our everyday life, like connecting smartphones to batteries and TVs to recording devices. However connectors also fulfil the connection and separation needs at a production site and have 4 main merits: ease of maintenance, scalability, transportability and productivity.
For example, “Connector Maintenance” is...
Let’s think of when a smartphone’s display (screen) breaks.
● Without connectors
Need to buy a new smartphone to replace the broken phone
● With connectors
Only the damaged display needs to be replaced since the display is joined by connectors
Additionally connector “productivity” refers to parallel production of each unit and easy assembly with connectors, reducing mass production and overall production time.
Connectors improve transportability since large devices such as equipment can be divided into appropriately sized units and then transported easily.
Connector scalability can be seen in computer memory expansion.
Depending on the connector improved maintenance and scalability enable environmental benefits such as conservation of resources. The productivity and transportability also result in production cost reduction and contribute to high product quality and lower overall costs. For electronic devices connectors are a must-have component.
There are many different connectors based just on size and appearance but overall connectors can be divided into 2 categories. The first category is external interface connectors for connection between devices. The second kind is internal connection connectors that connect the inside of a device.
As the devices of the world are becoming smaller, high speed processing is becoming possible and high capacity batteries are being equipped in these devices, external and internal connectors have evolved based on altering the shape and changing functions for various applications and uses. For that reason there are a multitude of types.
Let’s take a look at the kinds of connectors.
● External Connectors
● Internal Connector
Connector design varies on the type but in general consists of terminals, an insulation case, and an outer shield.
● (Ex.) Interface connector
Since terminals conduct electricity they are a crucial part of a connector. In general an electrical connection is established when the rod-shaped male contact and the springy female contact touch.
The insulation case preserves the terminals and insulates between the terminals as well as between the terminal and exterior shell.
The exterior shell covers the insulation case including the terminal and protects the terminal from shock and dirt. Additionally the case can be used as a lock function or for electromagnetic noise (EMI) prevention.
Connecting a connector to a board is called “mounting” and there are three typical methods.
DIP mounting is a method of mounting in which contacts are inserted through a hole for fixing the board in place (through-hole). In order to attach from the backside the retention force needs to be high. However since it difficult to adjust the amount of solder, a solder bridge can occur if the distance to the next terminal is short (defect in which the adjacent terminal connects to the soldering). There is also the demerit of occupying space on both sides of the PCB board due to the through-holes.
SMT (Surface Mount Technology) mounting is a soldering process in which solder paste is painted on the mounting part of the PCB surface. Afterwards surface mount components are placed on the board and soldering is set by melting using a reflow machine. Since only space on the front side is used for mounting the back side of the PCB can be used more effectively. This method is also useful for small components since it is possible to apply solder only to the mounting portion. However since components are attached only to the front the retention force is weaker in comparison to DIP.
Press-fit is a method of mounting in which the contacts are pushed into the through-holes of the PCB board. It is an effective method when wanting to avoid the use of solder. Additionally there is little deterioration even over long time periods such as 10 to 20 years since no solder is used. When mounting a board able to withstand press-fitting and a press device are required.
The methods of connecting cables can be divided into 3 types.
Solder termination is an old termination method in which metal is connected by melting the soldering. Generic tools can be used but the worker ability and tools used impact the termination quality.
Crimp termination is a termination method in which the metal contacts are squeezed and cable wire is wrapped around the contacts until they touch. Tools suitable to each terminal’s size are required but variation based on worker skill can be reduced. This method is also compatible for mass production if an automatic crimping machine is used.
IDC termination requires pushing the cable through the IDC contact slit until touching. Flat cables (also referred to as ribbon cables), which caused IDC to become a termination method used worldwide, are pre-aligned into flat electrical wires. Multiple terminations can be performed at one time, resulting in high operability. However this method is not suitable for high current as the contact area is small.
Noise is unintentional and unneeded signal.
Specifically it occurs in audio as “static” and “image distortion” in video.
Since noise is unneeded noise elimination and/or reduction measures are necessary for connectors and cables it is common to use a shield for noise prevention.
● Shielded Connector
● Shielded Cable
Transmission rate is the speed in which information is transferred.
Information encoded/coded for transmission is called a signal. The smallest unit of signal is referred to as “bit”. The amount of signal that can be sent in one second is called “bps” (bit per second).
Another unit of equal speed is called T/s (Transfer per second).
Let’s think of a scenario in which an hour long video recorded on a video camera is imported to a PC.
Assume the one hour video is 5GB (gigabytes)
*Byte refers the amount of data and since 1Byte=8bits, 5GB=40Gbit
When using a USB Type-C type with a transmission rate of 10Gbps it will require at least 4 seconds to import the video.
(The actual times vary based on cable used)
As digitalization advances the amount of data is becoming increasingly larger.
For that reason connectors and high-speed transmission are required.
 |  Dr.H is very knowledgeable. He knows everything about connectors. Dr.H always explains nicely when Little Q doesn’t understand something. If you look closely, you can see he is fluffy like a sheep. |
Dr.H is very knowledgeable. He knows everything about connectors. Dr.H always explains nicely when Little Q doesn’t understand something.
If you look closely, you can see he is fluffy like a sheep.
 |  Mr. A is a childhood friend of Dr.H. He says “Uhhh...” a lot. He likes playing cards and is quite strong. His way of walking is so intriguing that people feel relaxed just by watching him. |
Mr. A is a childhood friend of Dr.H. He says “Uhhh...” a lot.
He likes playing cards and is quite strong. His way of walking is so intriguing that people feel relaxed just by watching him.
 |  Little Q is very curious and interested in everything around him. Like a young Edison, he is always asking everyone around him “What?”, “Why?”, and has an innocent heart. |
Little Q is very curious and interested in everything around him.
Like a young Edison, he is always asking everyone around him “What?”, “Why?”, and has an innocent heart.
