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The Great Outdoors: How to select parts for water and dust resistance

Jun 26, 2017

The Great Outdoors: How to select parts for water and dust resistance

Last year, I wrote about the trends in PCBs – reduce size but more computation power, features and capabilities.  One major benefit of the reduced size and increased efficiency is the ability move the products that might have traditionally in a fixed indoor location.   More and more, products are now being pushed into “The Great Outdoors”.

We’ve had repeated request to help our customers learn more about designing outdoor products.   This is the first in a three part series on how to determine what is required and select components.  Our focus in this blog is how to select parts for water and dust resistance.

First, we need to determine the IP rating required for the entire product.  IP ratings set the level of dust-proof and water resistance a part and/or product has by design.  IP stands for International Protection Marking and is defined by the IEC standard 60529.   IP ratings are a two digit system XY; where “X” is the dust proof level and “Y” is the water resistance.   For electronic components, dust proof is almost always set to the highest level; or X = 6.  Level 6 requires the component to be dust tight – complete protection against contact. 

The variation for electronic components are usually based on “Y” – the water resistance.  As a pair, the most common IP ratings are in laymen’s terms:

  • IP 64: ability to withstand a splashing of water
  • IP 65: water jets – equivalent to being able to withstand light rain
  • IP 66: powerful water jets – equivalent to being able to withstand heavy rain
  • IP 67: immersion up to 1m depth – think in terms of being “water resistant”; submergible to about 3 feet
  • IP 68: immersion 1m or more – commonly considered “waterproof”

The electronic components that are exposed to the exterior of the product should at least start with the IP rating that fits the need of the product.    But our work is not done. We need to examine the part’s design and fit to the rest of the product.  Afterall – the goal is to ensure the entire product has resistance to the level we want; not just the individual part.  

Let us use an exterior connector as an example; because it is one of the more trickier parts to look at from a design point of view.  There are five things you will want to look at in addition to the IP Rating:

  1. Is the exterior isolated from interior of the part? You will want to look for a sealed design – where if water gets into the front of the connector, it does not leak water into the rest of the enclosure.  

  2. How does the connector form a water-resistant seal to the enclosure?  The panel mount design connectors specify a common shape – circular usually – and have a gasket designed to seal the connectors to the enclosure.   Other connectors provide a rubberized material that allow for a press-fit to the enclosure. We usually get the 3D model of the connector so that customers can design their enclosure for a snug fit.  

  3. Does the connector need to form a seal to the cable at the same water-resistant rating? This is a use-case consideration.  Some connectors may not be expected to be plugged in all the time – as in the case of USB.   If so, you will want to examine how the connector-to-cable connection still retains the water resistance rating. 

  4. Will the cable encounter pulls or pressure while it is connected to the connector?  If so, we will recommend a connector and cable pair designed to withstand pulling, tugging, and bumps.  For most situations;  the connector and cable pair will use an additional interlocking configuration.  But there can be cases where the connector and cable pair need to break-away cleanly with auto-seal covering the connector.

  5. How much dirt and dust will the connector encounter?   Though the connector part may be rated level 6 “dust proof”; the dust and dirt collection on all the contacts might render the product useless if the product is placed on the ground or used in a wet/dirty environment.  We recommend a jack or socket connector that includes a rubber cover. 

In Table 1, I’ve tried to identify the most common exterior facing components to the typical product.  Match the part’s IP rating to the IP rating you have set for the full product.   Test the part for its ability seal to the enclosure and maintain products’ overall IP rating.   There Maybe additional test for these areas depending on the usage of the product.  

Exterior Facing

Set IP rating

Interior isolated from exterior?

Does it Seal to the enclosure?

Does outside element (cable) need to seal?

Protection against physical usage?

Additional cover due to placement?

Connector

Match

Test  

Test

Maybe

Maybe

Maybe

Switch

Match

Test

Test

N/A

Maybe

Maybe

Sensor

Match

Test

Test

Maybe

Maybe

Maybe

LED

Match

Test

Test

N/A

Maybe

Maybe

Displays

Match

Test

Test

N/A

Maybe

Maybe

Antennas

Match

Test

Test

Maybe

Maybe

Maybe

Regulatory Labels

N/A

N/A

N/A

N/A

Maybe

Maybe

 

To reinforce the design process, we have provide examples of custom solutions and projects in the image collage:

  1. External Magnetic Base for an Antenna from Suntsu - upper row

  2. IP-67 Waterproof Switch from Shin Chin Industrial - bottom row left

  3. LED holder and assembly from Shin Chin Industrial - bottom row center

  4. IP-67 Waterproof USB 3.1 Type C from Suntsu - bottom row right

Also very important for outdoor products; don’t forget to consider water and dust resistance for the regulatory (and cosmetic) labels on the enclosure.

Contact us at sl@nexsuninc.com or 949-680-4725 if you need an design support and guidance.