Automotive Connectors
In the following we would like to share some collected basic information on Connection Systems to help the reader and user to understand common wordings, submit some technical background and to raise your interest for this very exciting world of connection systems. It might sound surprising – but connection systems and all related topics are a fundamental science at its best. So we will try to introduce you to the basic elements, their wordings and functionality as best and easily as possible. Your personal input in helping extend this live data file is highly appreciated!
Basics
Connectors are mainly used to connect or disconnect electrical lines. They are used to connect or disconnect prefabricated parts or devices to the given wiring harness. A connection system consists of two mating connectors which are combined into a fully working connection system. On the male side you will have to use male terminals/pins and on the female side you will have to use female terminals/pins. The terminals are mainly produced as metal stamped terminals available in different shapes and plating depending on the used application. Connected matching terminals (male+female) are the items which insures that the user has a linked electrical connection. The connector housing is used as an insulating body [1].
But what makes an automotive connection system different to an industrial or telecommunication connection system for example?
Characteristics of automotive connection systems
The main difference of automotive connection systems to any other branch is the very high level of technical reliability set by OEMs (Original Equipment Manufacturers) like e.g. GM and/or VW. Besides a variety of environmental conditions inside a car (high temperature, vibrations, splash water, oil, braking oil and many more) connection systems need to be connectable and/or disconnectable in rough working conditions. Producers main tasks are to invent connection systems to a very high level of functionality combined with a malfunction rate of zero taking into account increased amounts of connection systems per car. This production requirement is also valid for used terminals and allows this specific industry to find a variety of special technical solutions. [2].
Wire-to-wire Connection
At this type of connection a male connector is linked with a female connectors and “filled” with terminals on both sides. As a result you will have a linkable part of a harness. Mainly this kind of connection is used to connect or disconnect any small application (e.g. electrical window lift) with the main power harness or any other kind of partial harness. A very common wire-to-wire connection system is Metri-Pack 280.Synonym: Wire-to-wire Connector, Inline Connector
Board-to-wire Connection
This kind of connection system is used to fix a connection onto a conductor board. Mainly the male connector named “PCB Header” is fixed with the conductor board. The female connector is linked to the male connector so the female terminals are connected to the wiring harness. A very typical Board-to-Wire connection is to connect the engine control unit with the power harness. A good example is Micro-Pack 100W Header Unsealed Series.Synonym: Board-to-wire Connector, PCB-Header
Device Connections
Here we have the mating part already assembled within a device. Mating parts on devices are mainly the female connectors matching to the given application. In most cases the assembled male connectors are not available for sale. Very annoying for most developers who want to build up connection systems for testing purposes. Example given for a common Device Connections can be found in sensor applications as the Metri-Pack 150.2 Pull-to-Seat Series.The Components of Connection Systems and their functionality
In the following you will find the general elements of connection systems, their wordings and functions in any connection system. Your hints and personal input would be much appreciated in keeping this Wiki alive.
Connector housing
The connector housing is used to carry the pins/terminals. It is made of insulating plastic and its shape secures the connection with the given mating part. The design differentiates between male and female connectors as well as sealed and/or unsealed connection systems. In a sealed connection system you will generally find a radial sealing to protect the electrical system from water or dirt influence. This is located between the male and female connector [2].To avoid misconnections many connectors are produced in different codings. The coding of a connector is often realised by a variety of notches inside the connector. As these notches are not visible at first sight, these coded connectors manufactured by Delphi Connection Systems are mostly marked with different colours so these are easy to use even for people new to the business. The connectors shown in the pictures above are good examples of connectors with different coding. (Picture left 12059181, right 12059183)
Synonym: connector, connector housing
Secondary Lock / Terminal Position Assurance (TPA)
Terminals are mainly assembled by hand into the connector housing. To do this each crimped contact must be inserted fully into the connector to insure a completed technical link. The insertion force varies from the different connection systems and its use. On many connection systems you will here a slight „click“ as soon as the terminal is pluged in. This slight click sound is established to avoid mistakes in mass production. You can imagine that if any worker is assembling terminals 8 hours a day mistakes might happen and these need to be reduced as best as possible. If you consider that a worker can make a maximum error of one mistake in three months he has a mistake rate of less than 10 ppm (ppm = parts per million) [2].Furthermore securing a perfectly assembled terminal with given connector Secondary Locks are used. Secondary Locks are produced and available for nearly all connectors differing in shape of terminals and shape of each connector housing. The use of a secondary lock insures the terminals are fixed perfectly in its end position. Some secondary locks fulfil the function of strain relief [2]. The pictures besides shows two different kinds of Secondary Locks.
(Picture left 12059185, right 12010852)
Synonym: Secondary Lock, TPA, Strain Relief
Connector Position Assurance (CPA)
Each connector is assembled with its mating part to a connection system by hand. The required mating force differs from the amount of cavities, terminal and connectors shape. If the connectors are not fully assembled you might have an electrical connection, however it's not protected from water, dirt or vibration influence and might lead to a malfunction of the connection system. To secure the correctly assembled connection system a Connection Postion Assurances (CPA) is used. Connection Position Assurances are available in many different shapes, as preassembled parts and many more – always depending on each connection system and their technical use. Nevertheless the Connector Position Assurance will always indicate to the user through a slight click sound that the connection is assembled perfectly. (Picture left 12020833)Synonym: Connector Position Assurance, CPA
Single Wire Seal
Single Wire Seals surround the single conductor and seal the cavity against environmental conditions. Seals are crimped to the terminal and to the cable in one working step and than pushed into each cavity. Due to manufacturer and series a seal varies from 2 to 3 sealing disks which are forced from the inside against the cavity. Depending on the manufacturer and series the single wire seals are retained with different percentages of silicon oil. The use of this oil supports the assembly process while inserting into a cavity.(Picture left Delphi 12015899)
Synonyme: ELSeal, Single Wire Seal
Blockseal
Blockseals have the same functions like single wire seals. They also protect the cavity against outdoor influences. As a main difference a block seal offers several openings to retain several cables in each opening. Therefore a blockseal protects several cavities. Blockseals are not crimped to any terminal as they are already assembled to the connectors body(Picture left Delphi 12110489)
Synonyme: Blockseal, Multiple Cable Seal
Cavity Plug
Cavity Plugs are used to block unused cavities and protect these against environmental conditions. Inserting a cavity plug can be done by hand. The top edge of the cavity plug should be pushed in a minimum of 2 mm into each cavity. To remove the cavity plug you can use a screwdriver.The following picture reflects a standard cavity plug as an example.
(Picture left Delphi 12010300)
Synonyme: Cavity Plug, Plug
Design of Terminal Systems
Terminals are differentiated by gender into „male“ and „female“ terminals. Female terminals are manufactured with one or several spring elements which show a bell-mouthed opening. This aperture makes it easy to find and insert the male terminal. The male terminal is slightly thinned at its cone point and can be fixed easily to the female terminal spring elements. The zone for inserted male and female terminals are called contact zones. While assembling male and female terminals the male terminal is slightly elastically deformed in order to reach the desired electrical pressing force. The pressing force is a basic factor while working with terminals and connection systems. Terminals ends are named „conductor wings“. These wings are used to crimp the terminal to the cable [1]. (Picture left 12103881, right 12045773)Synonyms: Terminal, Single terminal, male terminal, female terminal
Performance indicators of Terminals
Contact resistance
Contact resistance is a sum of the following single resistor factors:- Ferule Resistor: depends on the used method of assembling terminals (e.g. crimping, soldering etc) and its assembling quality. To reduce ferule resistor to the lowest possible level it is highly recommended to use the correct cable and correct cable diameter on each terminal. It is also highly recommended to use the professional crimping tools available on each terminal. In general the terminal producing companies do offer crimping specifications for each terminal to insure terminals are used effectively. Crimp specifications can be requested at DeyTrade.
- Resistor force of male and female terminals: Short overall length, big cable diameters and used material with high conductance secures best possible value of resistance.
- Contact resistance at contact zone: Contact resistance at contact zone is a result of constriction resistance and surface contamination resistance. The constriction resistance lowers by raising the contact surface, raising terminal normal force and raising electrical conductance. Depending on the terminals surface coating a thin corrosion coat can be found inside the terminal connection. The corrosion coat has its own resistance differing from used terminal systems. While assembling or disassembling the terminals the corrosion coat can be destroyed [1].
Continuous current-carrying capacity
Continuous current-carrying capacity is one of the main characteristics. Continuous current-carrying capacity is given in Ampere [A] and is limited by heating as a result of the current flow. Responsible for the heating process of terminals is the terminal resistor [1].Plug- and Pull-Force
The used plug and pull force is mainly influenced by the sum of mating force of each terminal system. The friction between the connector housings is insignificant. The more cavities inside a connection system that are used the lower plug and pull forces are needed to secure terminals from damage and to make plug-in easy. Plug and pull force is influenced by form and shape of each terminal, surface roughness and hardness of given terminals. [1].Material for Terminals
Basic material: The basic material of any terminal needs to have a very high electrical and thermal conductance to reduce heating at its best and to insure best possible current carrying capacity. For these reasons the favourable material used is copper and its alloys. The requirements in the automotive industry for terminals material and a trend to miniaturisation led to a change in material use. Copper-Zinc (e.g. CuZn30) and Copper-Bronze (e.g. CuSn4) are slowly beeing replaced by Copper-Nickel-Silicium (CuNiSi) alloys.CuNiSi alloys are showing better results regarding resistance and conductibility. As a result you will be able to have terminal systems with higher ampacity and higher limit temperature [1].
Terminal Plating: To avoid corrosion basic materials of terminals are galvanized. Common terminal platings are gold, silver and tin.
Gold Plated Terminalsare used at:
- extreme electrical conditions: very small allowance of changes in contact resistance, submitting signals at small voltage levels and high data rates.
- extreme environmental conditions: very high pollutant concentration and temperatures above 150°C, high vibration surroundings, high rate of assemble and disassembling over lifetime.
- extreme reliability: long lifetime, low error probability.
- Terminal systems with low terminal normal forces
Silver Plated Terminalsare used
- at High Voltage Systems,
- if value of assemble and disassembling terminal/connection systems is 20-50 over lifetime
- to avoid fretting corrosion
- if surrounding temperature does not exceed 140°C-160°C
Tin Plated Terminalsare the most common used terminals and are mainly used
- if value of assemble and disassembling terminal/connection systems is 10-20 over lifetime
- if surrounding temperature will not excess 130°C-150°C [1].
[1] Volker Behrens: Elektrische Kontakte – Werkstoffe, Gestaltungen und Anwendungen in der Nachrichten-, Automobil- und Energietechnik. expert Verlag, Renningen 2010, S.106 f.
[2] Günter Knoblauch: Steckverbinder – Systemkonzepte und Technologien. expert Verlag, Renningen 2002, S.211