We are in the midst of the fourth industrial revolution driven by Smart Technology. Transitioning to this next phase is happening fast and is changing the way we live, work, and play. This blog post covers the technology trends in the electronics industry and provides information on how material testing is used for electronics applications via three case studies:

  1. Leading Printed Circuit Board Manufacturer Turns to ADMET for Innovative Testing System
  2. Various Bend Testing Applications for a Glass Coating Company for Consumer Electronics Industry
  3. Thin Film Biaxial Tension Testing for the World Leading VR Manufacturer

Technology Trends in the Electronics Industry

In the 20th century, the Internet started as a proprietary technology used for U.S. government research. More than half a century later, it’s exploded into the worldwide web linking devices, objects, and people. The electronics industry has realized the benefits of Smart Technology for some time. Along with the Internet and the Internet of things (IoT), cloud computing and wireless sensors have also promoted its growth.

Such game-changing group of technologies makes the availability of smarter, more efficient electronic devices possible from any location while gathering and analyzing data so users can remotely or automatically control the functions of these devices, like cars, smartphones, and home appliances, to their liking. 

Wearables technology via integration of electronics into watches, fitness trackers, fashion accessories, footwear, glasses, and more, is at the forefront of the IoT. Consumer demand for smart-home ecosystems is also on the rise. Devices and services, like Apple TV and Amazon Fire Stick, or Netflix and Hulu have changed the landscape for at-home entertainment. Smart thermostats like the EcoBee or Nest provide users more control over the comfort of their homes. Lastly, companies like Samsung have utilized Smart Technology, allowing consumers to manage their home appliances from an app on their phones.

Case Studies

Leading Printed Circuit Board Manufacturer Turns to ADMET for Innovative Testing System

Challenge 

ADMET was contacted by one of the world’s leading manufacturers of flexible printed circuit boards to help with a new testing application. These boards are used to connect electrical components in various electronics such as mobile phones, laptop computers, and medical devices. The flexibility and thinness of these circuit boards have enabled cell phone manufacturers to design ever more compact and powerful mobile phones. Mobile phones, especially those that are of the flip variety, pose a challenge in the design of flexible circuit boards that can be repeatedly bent and maneuvered into narrow spaces yet remain very durable. New materials and laminates had to be developed that could pass stringent durability testing. At the same time, new testing equipment was needed to validate all of the new designs. 

Testing Application

The first step was to determine an appropriate test method. It was determined that the circuit boards needed to be fatigue tested in both the tensile and flexural directions. Designs of new products change so quickly that a very fast method of testing materials was needed. One test that was deemed appropriate was to stretch the materials going into the circuit board to 100% of starting length 30 times per minute. A normal universal testing machine can be configured to reach those speeds but it is not realistic for a system that needs to test into the millions of cycles. 

Solution

ADMET recommended a low force, voice coil actuated fatigue system from the ADMET eXpert 1900 series controlled with MTESTQuattro testing and fatigue software. The recommended system had:

  • 100mm of crosshead displacement
  • Maximum cycling speeds in excess of the requirement
  • Control software that could fatigue the sample with a sawtooth or a sinusoidal wave profile.
eXpert 1900 ready for fatigue testing

eXpert 1900 ready for fatigue testing

The materials going into the circuit board were not allowed to fail or allow the force at maximum strain to drop below an acceptable force threshold within 200,000 cycles. Using ADMET’s MTESTQuattro software, ADMET engineers programmed and saved a test method with a sinusoidal wave profile that cycled the sample to 100% strain 30 cycles per minute. The system was set to record every 1000 cycles and stopped automatically when the sample failed. At this point the number of cycles completed successfully was noted. The customer can look at the force vs. time graph to determine peak forces across all cycles to make sure none of them dropped below a minimum force reading. The system has already helped in the material selection process. It will continue to serve the quality control department as well as be used for further R&D purposes.

Various Bend Testing Applications for a Glass Coating Company for Consumer Electronics Industry 

Challenge

A leading supplier of thin-film processing systems and highly advanced digital night-vision technologies for use in the defense industry sought out ADMET to measure the flexural strength of a Gorilla Glass 3 specimen. The material was a brand of glass coated with specialized glare and scratch-resistant material. 

Testing Application

The following three ASTM standards were selected  to collect the data:

  • ASTM C1499 – Standard Test Method for Monotonic Equibiaxial Flexural Strength of Advanced Ceramics at Ambient Temperature
    • Uses concentric/circular ring on ring fixtures
  • ASTM D790 – Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
    • Uses a three-point bend fixture
  • ASTM C158 – Standard Test Methods for Strength of Glass by Flexure (Determination of Modulus of Rupture)
    • Uses a four-point bend fixture

ASTM C1499 outlines a ring bending test method that applies load to the surface of a sample at a constant rate to obtain the sample’s surface strength. The sample is supported by a circular ring fixture, while the load is applied by a smaller, concentric ring fixture, resulting in an equibiaxial loading condition. This test method was used to calculate the flexural strength of Gorilla Glass 3 samples, instead of ceramic samples. Other minor modifications to the test method were applied.

ASTM D790 quantifies the flexural strength and modulus of samples using 3 points of contact until the sample either fractures or bends to a specified strain. The Gorilla Glass 3 sample was supported by two points of contact on the bottom while the third point of contact applied force to the sample from the top.

ASTM C158 employs 4 points of contact to calculate the same properties as above until the sample either fractures or bends to a specified strain. This test method uses two points of contact to support the sample from the bottom while two points of contact to apply load from the top.

Solution

ADMET recommended a few different options with custom and standard items, but ultimately the following solution was agreed upon:

Four point bend fixture on an eXpert 2600

Four point bend fixture on an eXpert 2600

A performance specification agreement was created between ADMET and the customer to allow the customer to collect results before shipping out the system. After the solution was built, the customer visited ADMET’s headquarters to perform multiple test scenarios on the equipment. Once the data was gathered and reviewed, the system was shipped and installed in the San Francisco Bay area facility. The customer was very pleased with the results and doing business with ADMET.

Thin Film Biaxial Tension Testing for the World Leading VR Manufacturer

Challenge

The customer for this project specializes in virtual reality hardware and software products. Within its product portfolio, the customer utilizes a high-strength and puncture-resistant material, polymer film. ADMET was contacted to design a custom solution to test this polymer film in a multi-axis application.

Testing Application

Ultimately ASTM D638 was the standard selected to perform the test and collect the data. This is a common standard for measuring the tensile strength of plastics (<1mm) before the sample breaks to assess its elastic properties. In this case, ADMET’s engineers adapted the standard’s test procedure to calculate the tensile strength of the polymer film when force is applied in two different directions. This test method modification is often applied to analyze the stress and strain distribution of film in different directions.

Test specimens and target data were provided to ADMET to aid in designing a custom solution that meets their needs. Such requirements included the need to stretch samples to high strain (polymeric gel samples remain elastic in excess of 1000% uniaxial strain), measure a range of loads from <1kN to >1kN while applying biaxial loading, and perform slow quasi-static fatigue tests.

This application required the use of an extensometer to measure the strain of this material in both uniaxial and biaxial testing applications. Due to the thin nature of the material, a clip-on extensometer was not a feasible option. While ADMET offers multiple brands of non-contact extensometers, the Correlated Solutions, Inc. VIC-3D DIC solution was the ideal choice for this application. Using this instrument, the customer is now able to not only measure strain in 2 axes, but also visualize stress mapping of the material, and utilize a Z-axis view of how the specimens are acting under load.

Solution

ADMET recommended its biaxial testing machine. It is configured to analyze a material’s tensile strength when force is applied to more than one axis. The final BOM consisted of the following: