The Issues that Occur with Soldering, Crimping, and Press Contact

Today’s electrical cable connectors are quite complicated to get it right for the do it your- self assembler unless they are well trained in several aspects of skilled assembly. Proper connections must be made between components for an item to function as engineers designed it to work. This post will discuss several areas of failures that occur when attempting to build a cable set without the necessary backgrounds in proper soldering or crimping and to a lesser degree – press-fit contacts.


Soldering could be viewed as the most difficult skill to master. In fact, in the field of electronics manufacturers who assemble circuit boards, employers very often either hire personnel who are certified in soldering or train them internally to properly solder/re-solder as in wave soldering of entire boards. The art of soldering involves making sure the connection doesn’t result in numerous conditions that can cause failures now or sometime down the road.

The issues that can affect wire to connector pins are a connection that is made without proper flux cleaning of the metal surfaces. The right balance of heat and timing is required to allow soldering flux to fuse/weld the surfaces either a lead base solder or one that is lead-free – if required. Lead-free soldering is more difficult to get proper and long-lasting results. Soldering that allows too much heat will result in melted wire insulation and melting of the plastic connector body. Too little heat applied causes poor flux cleaning action and melting of the solder resulting in what many call “cold solder joint”. The solder will appear darker and less shiny than normal. Cold solder can break apart from the connection entirely.

Proper Soldering Tools

Other defects include excessive amounts of solder, too little amounts used, soldering wire at an angle rather than parallel to the pin and not removing flux buildup when necessary (conductive properties to adjacent contacts). Having a precision temperature-controlled soldering station is invaluable along with frequent tip cleanings, not to mention the correct tip for the job. Another defect that includes all wire connection types is too long an area of striped off insulation. Great hand /eye coordination, judgment skills, and patience are needed especially for soldering.

Soldering Issue Examples


Crimping is another form of attaching wires. In this manner, expensive tools or machines are needed to physically bend the terminal end making strong electrical contact with the stripped wire end. And the number of terminal sizes available makes for an expensive outlay of capital to cover more than 1 or 2 sizes of manufacturing specialized tools of machines. Afterward, the crimped terminal is inserted into the connector but not fully completing the process.

Press Contact

The least labor-intensive electrical connection outside of purchasing cable assemblies is press contact. The wire end is stripped to the desired bare conductor and from there it is pushed into the terminal block where it is firmly held by specially designed metal “springs”. These connectors require proper stripping of the wires – neither too little bare wire or removing too much of the insulation can possibly lead to short-circuiting if wires touch or arching over of current.

Before the cable can be placed into use, a visual inspection must be performed to check for any missing parts, no damage exists, and the assembly needs to be tested for issues like being improperly wired (multiple wires misrouted) – this is checked by continuity testing which can also find the regular open connection. 

MISUMI Solution

MISUMI offers cable assembly services to create quality cables which are produced using manufactured tools and equipment. They are also soldered by certified soldering operators along with the cables passing the following quality tests:        

MISUMI’s Cable Product Certification

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One Comment

  1. Betty Hunt

    March 16, 2020 at 7:30 am

    Glad to read this informative blog. Thanks for sharing the issue in the soldering crimping.


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