Housing
☆ The main structure of the connector.
☆ other parts rely on it to determine the spatial positioning.
☆ Insulation function between conductor parts.
☆ size planning should take into account the molding.
☆ optional materials to be concerned about the customer's process conditions.
☆ due to the needs of the application section and need to limit the mold into the plastic mouth, should be marked on the surface.
It is the main component of the entire connector, the other parts to assemble it. It roughly determines the size of the connector, to confirm the structural strength of the end user can withstand the destructive use of the end user or customer specific test specifications (for example: the need to impose the direction of the external cable, can not see the damage; When installing screws, the application of appropriate torque can not cause damage).
Since it is the main component, naturally the responsibility of positioning the parts, so with other parts of the parts and the size of the tolerance (including geometric tolerances) need to pinch appropriate. Important feature (for example, the hole of the mounting terminal, the width of its drawer) can be set to a size of +/- 0.02 mm to ensure the function if it is determined by a single die and which can be machined by a grinder. Other geometric tolerances such as orthodontic degree, flatness, contour, etc. should also be used properly to ensure function.
The terminal in addition to the housing on the positioning of the space, but also rely on the housing of its holding force to produce the terminal mechanical behavior of the boundary conditions (such as cantilever terminal fixed end), and then in the male and female mating to produce appropriate Positive force, while avoiding the back pin of the situation occurred. So the terminal and housing interference section size and shape must be very careful. The appropriate terminal barb shape and the amount of interference in order to get the appropriate terminal retention, and will not cause too much interference caused by housing deformation or rupture.
In terms of electrical function, the housing shoulders the insulation function between the conductor parts, the general engineering plastic resistance value, as long as the injection molding to do the thickness of the subsequent processing and did not cause structural damage, the plastic insulation resistance and resistance Voltage effects can meet the specifications. Only in the highly hygroscopic material or the terminal pressure caused by the collapse of the plastic compartment caused by the case may occur plastic part of the insulation resistance or resistance to voltage failure of the situation, or most of the fear of exposure to plastic outside the conductor The insulation effect between the parts, because the air insulation effect is far less than the engineering plastics.
Housing design in addition to consider the above-mentioned functionality, but also to consider the injection molding of the manufacturing, too thick or too thin or uneven thickness are not suitable, too thick is shrinking serious, too thin is not saturated, uneven thickness Plastic flow imbalance when the flow is easy to cause cooling warpage. Usually the manufacturer is responsible for drawing the functional model of the parts to the mold design engineer, the mold engineer will be determined according to experience where to add what kind of escape material to improve the formability, but if the original design of the flesh Size has been very small and the proportion of thick and thin cases, the mold engineers can not rely on fugitive adjustment, the system should avoid such a situation. After the mold engineer is planning to do the job, it should be consistent with the functional requirements of the structural strength of the frying material (and sometimes the effect of the reinforcing structure on the other parts of the assembly, : Rigid shell just good enough, then through the riveting in the housing, the overall rigidity is enough), confirmed after the mold flow analysis and mold action.
Plastic materials are simply divided into high temperature materials and low temperature materials, the material heat distortion temperature and the general SMT process temperature comparison to distinguish between high temperature materials and low temperature material. General notebook connectors are required to go through the SMT high temperature process, it must use high temperature material. In some cases, it is necessary to retain a sufficient plane on the surface of the housing for the customer to use the vacuum suction area of the automatic plug-in. Therefore, it is necessary to avoid the placement of the adhesive point or the mold bonding wire there, so as to avoid the vacuum nozzle failure.
Housing the bottom of the design should pay attention to, to avoid pressure on the PCB coated with solder paste, so as to avoid short-circuit between the pad, so standoff design. In addition, standoff has another function, is to provide SMT type solder tail to adjust the commonness of the benchmark, but also by adjusting the height of the standoff to compensate for the housing warping deformation.
Two
☆ telecommunications transmission of the bridge, do signal or power transmission, but also by shortening the terminal to do Detection to confirm whether the public is fully connected.
☆ to confirm their mechanical behavior, to provide appropriate positive force, male and female with the insertion and tear force, retention, and remain within the elastic deformation range.
☆ To ensure electrical function, still need to pay attention to the size of the terminal, copper and plating specifications.
☆ When there is a long pin arrangement, the convenience of production assembly should be considered.
☆ male and female terminal wiping distance should be enough.
☆ male and female contact area and SMT welding area to avoid cutting hair, if necessary, coining into the spherical surface to avoid scratch contact.
☆ SMT tail shape and size of the appropriate arrangements.
☆ fine pitch insert molding products, to avoid the plastic coating to the tin terminal area of the terminal, so as to avoid the case of melting tin short circuit.
☆ elastic terminal in the vicinity of the cantilever should avoid large angle, small radius of the bend, so as to avoid the cracks caused by bending the terminal life.
☆ through hole type terminal foot pitch can not be too small, otherwise the customer's PCB or lay line will be a problem.
The main function of the connector is to rely on the terminal to the telecommunications from one circuit system to another circuit system, so the male and female connector after the connection, to ensure that the male and female terminals have a sign and a good electrical conduction. In addition to the parent housing shell and shell and other parts of the male and female terminals fall in the correct interchange position, still have to ensure that the male and female terminals between the contact force is large enough to allow the telecommunications through the contact surface, if the contact with the positive Force is not enough, then the contact surface of the micro-state is only a slight point of contact, only sporadic little point of contact, the impedance value may be large to several Aum, resulting in too much potential drop, so that the telecommunications receiver can not handle. Usually the hardness of the gold-plated surface is low and the conductivity of the gold is good, so the positive force of the contact surface can be 20gf can sit back and relax, but the designer must have the concept of tolerance, not the design of the nominal value set at 20 gf, At about 40 gf or so. Because the general I / O connector plug life of thousands of times, which means that the terminal must be done when the elastic deformation of the deformation at the end of the resistance test can still maintain the appropriate contact with the positive force in the terminal selection On, C5210 is not easy to drop than C5191. In addition, the contact area of the terminal area of the gold-plated film thickness must also be able to withstand thousands of times of wear and tear, usually, to be resistant to 5000 plugging the docking conn. And module conn. In the contact area are gold-plated 30micro-inch min. In order to make the connector as a whole do not insert the force too much, so as not to use is not easy to cause even the terminal was thrown back, top collapse, we must pay attention to the front end of the guide slope can not be too steep, generally designed below 40 degrees.
The holding capacity of the terminals is set so that the lower limit of the required specification is much larger than that of the terminals when producing the on-line force retractability due to the reduced holding force of the connector after the high temperature of the SMT. For example, every The interdigital insertion force of a terminal is 30 gf, but the retention force is set at 300 gf min, taking into account the variation of the tolerance, the poor condition of the user's plug and the disruption of the high temperature of the SMT.
The LLCR specification of the terminal, in addition to considering the contact resistance between the coating of the contact surface and the forward force, must take into account the conductor impedance of the terminal itself, depending on the material of the terminal. Brass conductive good but poor mechanical properties, only for the public terminal; phosphorous copper conductivity is poor but the flexibility is good, can be used to produce flexible mother terminal; beryllium copper both good flexibility, good conductivity characteristics, but the material expensive , Difficult to achieve environmental problems. After the terminal size is designed, it can be divided into several sections according to the cross-sectional area. After estimating the impedance of the conductor, and then adding the appropriate contact impedance, the LLCR value of the product can be estimated. If the product has different lengths of the terminal, then the maximum length of the impedance can be estimated.
Another electrical characteristic is the rated current, which also depends on the material and cross-sectional area of the terminal, the larger the cross-section, the smaller the impedance of the unit length, the less heat generated by the current, the smaller the terminal temperature rise, Conduction of the larger current (rated current is defined as: the terminal to pass the current, the temperature rise itself does not exceed 30 degrees Celsius).
The wiping distance of the male and female terminals can not be too short, on the one hand is to ensure that the effect of cleaning the surface dirt, on the one hand is to tolerate their own manufacturing tolerances and customer system of institutional tolerance, the general design, the shortest terminal should have 1.0mm wiping distance before insurance.
Length pin design, some is to reduce the overall insertion force and make short pin staggered; some is to allow the terminal to have a poor time, for example: hope grounding pin first connected, so there are several particularly long terminal as the grounding pin , And may arrange a few shortest pin at both ends of the frame as the detection of the terminal, as long as the shortest pin all connected, it means that the other signal terminals are connected (so the detection terminal to be arranged in the two end). Consider the product manufacturing tolerances, the length of the pin size differences should be appropriate, so as not to lose time in the worst case of the effect of the general 0.5mm as a difference, if a product has long and short three terminals, the difference between the length of 0.5mm, but also To ensure that the shortest pin of the wiping distance is sufficient, then the product size will become larger. The length of the pin arrangement, unless the customer due to other electrical functional requirements and to specify the location, or should consider the convenience of assembly in the factory, because either by continuous die directly out of the length of the pin or after the 2nd forming, always than The length of the terminal is more time consuming or more expensive to store the precious metal, so should be as long as possible or short pin and other special terminals are arranged in the same row of end material tape (some products such as docking connector is installed by the eight rows of tape Made, should avoid the length of the terminal spread in the eight discharge belt).
Some memory card connector, because the contact with the terminal is the gold finger on the memory card, some gold finger gold-plated texture is soft, the terminal is not smooth, plug three or five times in the cheat to see the obvious scraping Marks, so the terminal cup should be coining into a spherical surface to reduce wear. Otherwise even if the mold design cup surface for the shear surface is no hair, but after bending into a cup, where the upper edge of the two sides will be because of Poisson effect upturned, so when the male and female interchange only this up The two edges are tilted on the male terminal (or gold finger), and the wear problem is still serious.
SMT product of the foot design, in the horizontal section is best to have a Z-shaped bend to avoid the solder joints on the excessive thermal stress, in addition, the real tin to eat that section of the tail and the horizontal angle can not be too much, otherwise caused Only the end or bending point to eat tin, can not be tested by SMT solder. Terminal plating should be careful to avoid the tin area directly connected with the gold-plated area, so as to avoid SMT process in the solder (solder wicking) of the bad situation. When the product pitch is very small, the terminal by the housing part of the fixed and very short, it is difficult to rely on the assembly method to obtain a reliable holding effect and retention, then consider the insert molding (folder molding) way. Take this way in the terminal to pay attention to two points:
(1). In the mold within the seal part of the width of the terminal to be controlled in the 0.03mm (plus or minus a half) of the variation range (even the thickness of the coating should be taken into account), so as to avoid too much die Or too narrow hair. Another seal section should be a flat section, to avoid sealing the surface of the seal material.
When the high temperature liquid plastic flows through the surface of the terminal, the temperature may be higher than 300 degrees Celsius, will cause the terminal surface of the tin and lead melting with the plastic to the downstream flow, unfortunately, to the adjacent terminal, change Resulting in the short issue of the finished product. It is necessary to avoid the tin-plated lead extending to the plastic coverage area.
Elastic terminals in the male and female, the internal stress of the largest place in the cantilever of the root, should avoid any stress near the location of the situation, bending radius is too small caused by the crack is a serious stress concentration, should avoid the flexibility If there is a bend with a small radius near the root of the terminal, it is recommended to take the bending radius of more than twice the minimum R / T ratio of the material to avoid cracking. Some terminals are designed for secondary bending after plating and then assembled. The secondary bending point should be covered by the tin-plated lead area because the tin-lead coating is better and more ductile than the nickel coating, Bend and produce coating cracks, but also because it is relatively soft and easier to bend the rule to get scratches.
The terminal to press the way with the housing combination, often in the terminal pressure to the positioning, the governor back to the back when the terminal back out of some of the situation, it is best not to design a terminal shoulder (the rule of pushing the terminal Force point) and housing the surface after the cut, so as not to pressure in place. Usually the shoulder part of the terminal is exposed to the widest outside the housing, that is, adjacent pin spacing the shortest distance between the air, pay attention to the resistance voltage here. So far the customer can tolerate a minimum of 0.15mm PCB edge spacing, so if the pitch of the terminals in the mating frame is too small, the tail should be staggered in multiple rows to increase the PCB hole spacing.

Spacer
Spacer is the tail of the tail to do the precise positioning, to facilitate the connector connector on the PCB. If the space allows, can be designed to float: the customer receives the goods at the bottom dead center, the terminal tail protruding spacer bottom length is shorter, then the tail of the orthodontic degree of the most accurate, the customer directly aligned PCB hole insertion , Insert the process by the way to spacer up to positioning. The design should pay attention to how to make spacer stable positioning in the bottom dead center, will not fall off, it will not be due to vibration and self-loading to the top dead center, in addition, the assembly line, because the product inspection similar to the action of the board, so also To be designed to facilitate the use of simple tools to spacer from the top deadline