What is PCB environmental testing? Why does it require in PCB manufacturing?

With PCB contamination on the rise especially in certain geographic locations, the need for PCB environmental testing is also increasing. Essentially if your PCB has to operate in harsh environmental conditions, it is imperative to test the PCB assembly under those conditions so that you can be sure of their performance & efficacy. It is a specialized process that requires you to go with an expert manufacturer who has the necessary expertise to conduct these tests. The tests also require specialized equipment; in choosing the contract manufacturer, therefore, this aspect needs to be kept in mind. PCB environmental testing is particularly recommended in some mission critical industries such as military and defense.

Types of PCB environmental testing

Typically, when you think of environmental tests you tend to think of testing the boards under high temperature & humidity alone. However, there are a wide variety of PCB environmental tests and protection ways that include shock, vibration as well as mechanical tests. These tests need to adhere to the IEC 60068 environmental testing standards.

There are also few tests which are known as Highly Accelerated Tests including:

• Highly Accelerated Life test or HALT
• Highly Accelerated Stress Screen or HASS

These tests assess the reliability of products in controlled environments. Essentially the aim is to simulate the conditions and ensure that the product does not fail under them. Typically, environmental tests are performed in a small environmental chamber.

Sometimes though product engineers are wary of accepting HALT/HASS test results as they feel that the stresses placed on the system may be more than what is found in the actual environment. However, the disadvantage of ignoring these test results is that you can encounter product failure at a later date on account of these same reasons.

PCB Test for humidity & corrosion

A water absorption test is an important aspect of environmental testing as the PCB may often be deployed in an environment that is humid. For such a test the PCB is put in an environmental chamber with controlled humidity, The weight of the PCB before putting it in the chamber, and after, is taken. Any change in the boards weight is on account of the water that has been absorbed by the PCB. It is also important to see that the exposed conductors do not corrode. Corrosion is the exact reason why copper is normally plated with an alloy that is oxidation resistant.

Thermal Shock and Cycling

A thermal test is an extremely important test & involves simulating the operating temperature under which the PCB must work. The testing involves changing the board temperature and seeing how the expansion and contraction affect the reliability of the board. An extended form of thermal testing is thermal shock testing in which the board is rapidly subject to two extremes of temperatures. While the low temperature is below freezing; the high temperature is typically above the glass transition temperature for the substrate. The board, therefore, expands or contracts accordingly. During expansion high stress is placed on the conductors & the solder point. The mechanical failure points can thus be easily identified & any such areas can be addressed in advance so that you do not have to deal with costly errors later.

To sum up

While not all PCB assemblies need environmental testing, it is a prerequisite for those which are used in extreme environmental conditions where temperature, humidity, shocks, and more are primary risks that can affect the working of the PCB. Therefore, It is important that; working conditions are simulated and the PCB testing is robust.

The other important thing to note is that environmental testing requires specialized expertise as well as equipment. Hence the right contract manufacturer who has the necessary skills needs to be chosen. Sometimes there is the fear that environmental assemblies can affect PCB appearance. However, this fear is unfounded as your professional contract electronics manufacturing partner can offer a reliable cleaning process post the simulation. It is also important to check if the contract manufacturer offers batch-testing or offers environmental testing on all boards bases.

Done correctly, environmental testing can ensure product reliability, like little else.

Technotronix is an ISO 9001:2015 certified company who delivers one-stop PCB manufacturing services with specialized support, reliable testing, and multi-functional features. Our consistent quality and quick turnaround time captivate us with our customers, who look on us as a one-stop-shop for all their PCB requirements. If you have any requirements regarding PCB manufacturing or need urgent assistance, contact us at sales@technotronix.us or call us on 714/630-9200.