From my personal experience, I often had a hard time mating connectors because some of them were too tight to fit in. And, sometimes after I disconnected them for several times, I found they were worn out. I often wonder the reason behind this phenomenon, until a technician clarified this. He said,” This may result from a designing defect of female connectors.”
Photo courtesy: http://uk.rs-online.com/web/ Retrieved Jan 13, 2015 from http://img-europe.electrocomponents.com/euro/img/site/campaigns/iz/contact-type.jpg
The defect is usually related to” the clip” which is a key component of a socket (female connector). The function of a clip is to lock the inserted pin and form a contact area which ensures an electrical and mechanical connection between the pin and socket.
Photo courtesy: ebyelectro.com Retrieved Jan 13, 2015 from http://www.ebyelectro.com/images/precidip/socket_02.gif
The quality of clips is heavily influenced by the manufacturing process,in which the most important process is swaging. Swaging is a mechanical treatment which is evenly squeezing the clip to form oval shaped end. The purpose of this treatment is ensuring clips can tightly lock inserted pins when they interconnect. If clips fail to function, connectors will disconnect easily and transmission failure occur.
Photo courtesy: www.chinabaike.com Retrieved Jan 13, 2015 from http://www.chinabaike.com/uploads/allimg/140615/0S25RC3-9.jpg
The process also needs to ensure the proper contact mechanics and the smoothness of the clip surface. This can reduce the insertion force during connectors' interconnection and increase the performance and reliability .
Photo courtesy: www.mill-max.com Retrieved Jan 13, 2015 from https://www.mill-max.com/images/contact_clip_pin_range.jpeg
Some factories, however, would simplify the swaging process to increase their margins. For example, they skip the designing process of clip. Thus, the size will not be fit. It's will be either too big or too small. Moreover, some of them just produce clips as equal size of pins. As a result, the insertion would be difficult and clips would be flared out when pins are inserted. And, after plug out few times,the socket would lose its flexibility and wear out. This would lead to interconnecting failure, shorter life cycle, and transmission issues, etc.
Apart from size, clips has to be flexible and substantial. As a result, manufacturers usually produce clips with phosphor bronze or beryllium copper to ensure the flexibility and durability, while some factories don’t follow the proper process. They replace phosphor bronze or beryllium copper with downgrade materials. Those materials lack of flexibility and endurance. When connectors interconnect, it will cause extension failure of clips and harm both pin and clip.
Next time when you need connectors, remember to put some emphasis on detail to avoid the sequential problem.
Reference:
http://blog.sina.com.cn/s/blog_62491b7d0100xu1v.html
http://www.ebyelectro.com/preci-dip-socketcontact.asp
http://www.precidip.com/en/Products/MIL-Contacts/MIL-Contacts.html
http://www.chinabaike.com/uploads/allimg/140615/0S25RW5-3.jpg
http://www.radioandtelly.co.uk/connectors.html
http://www.chinabaike.com/t/32066/2014/0615/2456521.html
http://www.chinabaike.com/uploads/allimg/140615/0S25RC3-9.jpg