The basic knowledge of connector

1. what is connector

 Connector is a common part that we technology person connect with. Its function is very simple: Connectors is a regular component that electrical engineering and technical personnel contact with. Its function is very simple: it’s built a bridge between the interdiction part or isolation power so it makes the power flow to achieve the intended function of the circuit. Connector is an absolutely necessarily party in electronic equipment. Flow along the channel observation, you will always find one or more connectors. Connectors are changeable in form and structure, with the application object, frequency, power, application environment is different there are different kinds of connectors. For example, compare the connector and hard disk used on court light with the connector used to rocket ignited is very different. But no matter what kind of connector should ensure continuous and reliable smooth current flow. General reference, the connector which it connected to is not limited to current, the optoelectronic technology high development recently, in fiber-optic system, the signal transmission carrier is light, glass and plastic instead of the common circuit wire, but the optical signal pathway is also used to connect devices, their role and the same circuit connectors.

2. why we should use the connector

Support that is this is no connector what will happen. Then between the circuit conductor should use of continuous permanently connected, for example, we want to connect the electronic equipment with power, we must connect the both ends of wire, we should use some way to fix it(ex. welding),do this bring much inconvenient no matter use or manufacture use car battery for example. if the battery wire fixed on the battery, it increase work for car product or company to installing the battery. Increase the product time and cost. When the battery is damage need to replace, we should send the car to maintenance station. remove the old, re-welding on the new, for this we should pay more for labor costs, since have the connect can reduce much trouble, We can only buy a new battery from shop, cut the connector, remove the old one , installed the new one, reconnect is ok. This simple example illustrates the benefits of the connector , It enables design and production process more convenient, more flexible, lower production and maintenance costs。

The advantage of connector

Improved the electronic products production process, simplify the connector assembly process. Also the mass production process

Easy to maintenance, if some part out of work, we can replace a new one very quickly.

Easy to upgrade, along the progress of technology, if have connector, we can use new and better one to replace the old component, use connector can increase design flexibility when the design and integration of new products, and Components for component systems.

3. The Classification of the connector

several years ago, the classification of connector is confused, different company have its own method and standard, at 1989, at the support of NEDA(National Electronic Distributors Association, an industry educational organization) several big connector manufactures get together formulate a classification standard and term. molex company have joint in the process. NEDA STANDANDER, NEDA drawn up by the standard, known as Level of packaging) the overviews as below:

Level description:

0 IC chip or chip to the sealed connector, please note that the 1st level is "0" level, not "1" level. This class does not actually involve connection. 0 is the integrated circuit chip. Molex Inc. does not produce IC chips. But product the connector that connect the circuit boards to chip.

1 IC assembly or assembly to the (circuit) board connector when the IC chip is installed on board called 1 level connection

2. PCB to PCB connector called 2 level connector used to the connect between PCB.

3. Wire to broad or sub-assembly to part sub-assembly connector called 3 levels connector, used it to connect the PCB to sub-assembly or between sub-assemblies. Sub-assembly is a part of electronic products. According to the term of Molex Company, level 3 contained some wire to wire connector.

4. Chassis to the chassis or the input / output connectors called 4level provide power or signal connection. General experience: When involved the audio or video signals connected, or network and computer, using of this level connector.

About the above connector level, we need note the below point:

Some connector used more than one level ,for example 3 level connect QF50 and MX50 can used for 2 level or 4level, other example 4 level Molex input/output used for plug and sockets can also used for wire to board or between board connect.

During practical work, we rarely use level to talk about connector, but use outlook and connect method, for example board to board or wire to wire. Level is used for learn and classification.

The basic knowledge of connector

The structure of connector

The basic structure of the connector pieces are ① contacts; ② insulator; ③ shell (depending on species may be); ④ Annex

1. Contacts is the core part of successful finished the connect function. Generally have positive and negative contacts formed connect pair. The connector through the yin and yang connect each other.

     Positive contacts namely rigid parts is cylindrical in shape (round pin), Rectangular (square pins) or flat (Insert). Positive contacts are generally brass, phosphor bronze.

     Negative contacts mainly jack is a key component of contact, it relies on the elastic structure with the pin inserted in the timely occurrence of elastic force caused by elastic deformation of positive contacts with the formation of close contacts, complete the connection. The structure of many types of jack, a cylinder-type (split tank, necking), tuning fork type, cantilever type (vertical slot), folding type (vertical slot, 9 font), box (side jack) and the hyperbolic line spring jack ect.

2. Insulator Often referred to as the base or insert, its role is to make the contacts located according to the location and spacing arrangement and to ensure that between contacts and contact shell to shell with the insulation. Good insulation resistance, breakdown voltage performance and ease of processing is the basic requirements to choose insulator insulation material.

3 shells is the outside of connector, it offer the protective to install board and pin, and apply the right alignment to plug and sockets. So you can install the connector to the equipment.

4. Annex divided into sub-structure, and installation accessories. Structure accessories such as card ring tabs, pins, guide pin, connection rings, cable clamps, seals, gaskets, etc. Installation of accessories such as screws, nuts, screws, spring rings. Annex almost is standard parts and common part.

The basic feature of connector

The connector can divided into three category: Mechanical properties, electrical performance and environmental performance

1. Mechanical properties: the connection function, the insertion force is important to mechanical properties. Plug power connector into socket and extraction force (also known as separation of forces pull force), the two requirements are different. In the standard maximum insertion force and the minimum separation of power provisions, which shows that from the use of perspective, the insertion force is smaller (and thus have a low insertion force ZIF LIF and no insertion force structure), while the separation of power, if too small, will affect the contact reliability.

Another important mechanical property is the mechanical life of the connector. Mechanical life is actually a durability index; in national standard GB5095 it is called mechanical operations. A cycle include one insert and one pulled out ,after the required plug connector can normally complete their connectivity (such as contact resistance value) as the basis for evaluation.

The connector Plug power and mechanical life have relations with the structure (positive pressure size) coating contact quality parts (sliding friction coefficient) and the dimensional accuracy of contact arrangement (aligned degrees).

Electrical performance: The main electrical performance of connector, including resistance, insulation resistance and electric strength.

① Contact resistance high-quality electrical connectors should have a low and stable resistance. Connector resistance region from a few cents to tens of cents in Ω。

② Insulation resistance used to measure the insulation feature of electrical connector contact with connector and shell. The figure level is range hundreds of me ohms to several thousand me ohms.

③ Electric strength or resistance to voltage, medium voltage is characterized of nominal test voltage tolerance capability between connector contacts. And connector with shell.

④ Other electrical properties capability, the electromagnetic interference attenuation is a way to evaluate the effect of connector leakage of electromagnetic interference shielding, electromagnetic interference attenuation to evaluate the connector leakage of electromagnetic interference shielding effectiveness, generally test in the frequency range 100MHz ~ 10GHz.

In terms of RF coaxial connectors, as well as impedance characteristic, insertion loss, reflection coefficient, voltage VSWR etc. electrical indicators.

As the developing of digital technology, in order to connect and transmit high-speed digital pulse signal, there has been a new type of connector that is high-speed signal connectors, accordingly, in electrical properties, in addition to the characteristic impedance, emergence of new electrical indicators such as crosstalk, delay, skew etc.

4. Environment capability

Common environmental performance includes temperature, humidity, salt spray, vibration, and shock.

① Temperature current the connector’s highest operating temperature is 200 ℃ (except for a small number of high-temperature special connector) and the lowest temperature is -65 ℃. As when the connector work, the current cased heat at the point of contact, resulting in temperature rise, so generally the temperature should be equal to environment temperature and junction temperature. In some specifications, the connector specified point out the allowed temperature.

② humidity moisture intrusion will affect the connector insulation feature, and corrosion of metal parts. Damp heat test conditions relative humidity 90% ~ 95% (based on product specifications, up to 98%), temperature +40 ± 20 ℃, test time according the product, at least 96 hours. Damp heat test is more stringent.

③ the tolerant of salt spray, connector working in humidity and salt environment, its metal structure, contact with the surface treatment layer may produce galvanic corrosion and affect the physical and electrical connector performance. To evaluate the electrical connector's ability to withstand such as environment provides salt spray test. In this test handing the connector in the temperature controlled box, with the provisions of the concentration of sodium chloride solution with compressed air exhaust, the formation of salt fog, the exposure time according the product specification, at least 48 hours.

④ Vibration and shock   resistance to vibration and shock are important properties of electrical connectors, in special environments such as aviation and aerospace, rail and road transport is particularly important; it is the important indicator to test the mechanical structures solid and reliable of electrical contact to electrical connectors. In the test methods are clearly defined.

Impact test shall be provided that the peak acceleration, continue time and pulse shape, and the interruption of electrical continuity of the time.

⑤ Others environmental performance according to use, other rack mount connector

Circular Connectors

Nevertheless, some basic categories are still valid.

 

The classification and structure of connector pressure etc.

Performance of electrical connectors are sealed (air leak, the liquid pressure), liquid impregnation (of the bad habits of a particular liquid resistance ability), low pressure etc.

The classification and structure of connector