Connector Terminals Design On Memory Card
Texture of the memory card connector finger plated is a little soft.If connector terminals are not smooth, it will leave obvious scratches after plugging 3 to 5 times on gold finger. So terminals cup must be made into spherical surface to reduce wear. Otherwise, even if surface of cup is the shear plane without burr on the die design, The upper surface of the two edge will upward because of Poisson effect when bending into a cup. In that way, Wear problem is still serious, if there are only two retrousse edge sliding on the male terminals while male and female terminals are mating.
As to the welding foot design of SMT product, There should be a Z shape bending in the horizontal section to avoid excessive thermal stress on solder joints. In addition,the angle between the horizontal plane and tail plating tin can not be too large.Otherwise, there is tin only on the end or bending point.and it can not pass SMT solder inspection. In order to prevent the SMT process of adverse circumstances on overflowing tin, it is Vital for Electroplating of connector terminals to avoid directly connecting of Tin district and the gold zone.when the product space is very small, and the holding part and terminals assembly is very short. It is difficult to get reliable assembly holding effect and retention. Then we should consider the insert molding way.
Pay attention to the two points in connector terminals by insert molding:
In order to avoid crush and burr because of too wide or too narrow size, terminals width of the sealing material part in the mold should be controlled in 0.03mm (the plating thickness are taken into account). In addition, the sealing material should be plane and avoid sealing on the bending surface.
In the process of insert molding, When high temperature liquid plastic flows through the connector terminals surface, the temperature may be higher than 300 degrees Celsius. It will cause that tin of terminals surface melt and flow downstream with the plastic. Unsuitable connection to the adjacent terminals will cause that shortage of injection products. So we must avoid the tin lead extending to the plastic covered area.