If you’re designing a cable assembly to carry signal or power, you’ll need to select a connector that mates your conductors to your printed circuit board (PCB) or elsewhere in your product. And there’s a lot you’ll need to consider, from voltage rating to a variety of physical characteristics.
Spend enough time scanning connector data sheets and you’ll come across connector IP ratings, mating cycle ratings and mating/unmating force specs. All these indicate a connector’s physical characteristics, but they won’t all be equally relevant for your project.
Knowing which characteristics to prioritize for your cable design will help you choose the perfect connector for your cable assembly. This article will bring you up to speed on connector IP ratings and mating specs so you know where to focus your attention.
In reference to cable connectors, IP rating means ingress protection rating and denotes a connector’s level of protection against solid and liquid infiltration. The International Electrotechnical Commission (IEC) developed IP ratings with the intent of producing a simple way to label a connector’s protection.
Every IP rating has two numerals. The first numeral refers to the connector’s protection against solid objects, and the second against water. The below table articulates the meaning of these numerals.
| Solid object protection | Water protection |
|---|---|
| 0 – No protection | 0 – No protection |
| 1 – Protected against hand-sized objects | 1 – Protected against vertically falling water drops |
| 2 – Protected against finger-sized objects | 2 – Protected against vertically falling water drops if angled at 15° |
| 3 – Protected against objects larger than 2.5 mm around | 3 – Protected against spraying water |
| 4 – Protected against objects larger than 1 mm around | 4 – Protected against splashing water |
| 5 – Dust-protected | 5 – Protected against water jets |
| 6 – Dust-tight | 6 – Protected against powerful water jets |
| 7 – Protected against temporary immersion in water | |
| 8 – Protected against continuous immersion in water | |
| 9 – Protected against high pressure and temperature water jets |
Honestly, the numeral-by-numeral specifics of IP ratings tend not to mean much to manufacturers. When the cost of product failure is high, it’s not worth scouring old IEC documentation for exact definitions of “water jets” and “powerful water jets.” In our lane, there’s just not a meaningful enough per-unit price difference between an IP67 and IP69 part.
So talk to your cable assembly supplier. If you need a connector with water resistance, Deutsch connectors are universally available and rated IP69k, the IEC’s highest rating. It doesn’t make sense for manufacturers to split hairs over potentially ordering an IP67-rated connector instead.
On the solid side of the scale, you can easily see how some of the ratings would be irrelevant. An IP20 rating only tells you that you could electrocute yourself by sticking your locker key into the connection.
As with water protection, it doesn’t make sense to split hairs over dust protection vs. dust-tightness. Either your connector needs ingress protection or it doesn’t. If it does, there’s plenty of readily available connectors that offer airtight dust protection.
The three most common connector mating specifications are mating force, unmating force (sometimes referred to as retention force) and mating cycle rating. Typically, they aren’t all relevant for a custom cable assembly.
Mating force refers to the amount of force it takes to plug the connector in. Unmating force refers to the amount of force required to unplug the connector.
Guitar cables have low mating/unmating force ratings — the cable should plug in simply by hand, and it should release from the guitar should an errant bassist disrupt it on stage. Most connectors on consumer electronics have similar specs.
If your cable assembly is flexible and designed for motion (maybe it powers a robotic arm), a high unmating force could help ensure no connections break during standard cable movement.
Mating cycle rating refers to the number of times a connector can be plugged in and maintain its reliability. Every time you plug a connector in, its contacts are spread out, just the tiniest bit. Over numerous mating cycles, those contacts can become less effective.
Most consumer electronics devices use connectors with very high mating cycle ratings. USB cables, for instance, are typically rated for thousands of mating cycles. Since we mainly build cable assemblies for industrial applications, mating cycle rating tends not to matter. Some cables are meant to stay connected for years, others disconnected only for maintenance.
So prioritize the specs that matter for your application and feel free to disregard the rest.
Connector data sheets contain enough details to stall most people brave enough to read through them. Chances are, your cable assembly supplier can help you select the right connector for your next project.
If you have questions about specific connectors or about your application, get in touch. We’ll happily share our expertise. Request a quote for your next project, and you’ll hear back in less than three business days.
We’ll provide you with a fast quote (standard time is three days, can be as quick as same-day) and recommend manufacturability improvements.
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