NTS News Center

Latest News in Testing, Inspection and Certification

NTS News Center - Latest News in Testing, Inspection and Certification

Review of the 2017 IPC Reliability Forum

The IPC held their inaugural Reliability Forum this April in Chicago and by all accounts, the event was a resounding success!

NTS participated along side other industry experts from raw material and equipment suppliers, PCB fabricators, contract manufacturers and OEMs.

William Graver, NTS senior analyst, presented on a number of major reliability concerns in today’s environment in his session “Is test an unnecessary evil, or a life-saving necessity?”

You can read a full write up of the event, as well as other news from the IPC here: The PCB Magazine, July 2017.

Challenges of Meeting Dynamic Frequency Selection (DFS) Requirements

Dynamic Frequency Selection (DFS) requirements for products that operate in certain 5 GHz bands are now firmly established in most regions of the world. DFS is a mechanism that allows sharing of spectrum with radar systems operating in the 5250-5350 MHz, 5470-5725 MHz and in some regions of the world 5725-5850 MHz of the RF spectrum. Regulatory authorities required this sharing mechanism when the decision to open this spectrum up for uses like WiFi was adopted. The mechanism needed to verify that a channel is free of radar before using it, monitoring a channel for radar once a channel is in use, vacating the channel if radar is detected and remain off of a channel on which radar has been detected.

In some cases, the requirements have continued to evolve. For example, last year the FCC updated their testing procedures (KDB 905462 D02) for the Bin 5 radar type waveform to use a fixed width chirp in a given trial and changed which frequencies are used for each trial in the statistical performance check.

A continuing challenge is the requirement that the FCC pre test all products that are required to detect radar transmissions prior to a grant of equipment authorization being issued by a Certification Body. Depending on the FCC workload this can delay FCC certification by 1-3 months.

Since DFS compliance is primarily related to the software controlling a radio, it is necessary to involve software development personnel in DFS evaluation process that includes debug of issues found during testing. In addition, a description of how the product software that controls the radio DFS functions is secured to prevent tampering with by users of the product is necessary for product approval.

DFS testing involves different operation of the radio from other certification testing. Normal product operation with the added ability to restrict DFS functions and report detections are needed (KDB 905462 D04). Testing will proceed more quickly if a complete setup typical of actual use with the device configured to communicate with another product in a manner that produces a sufficiently high use of the channel (typically 17-30%). Additional information needed for performing the tests are the modes of operation, 99% bandwidth for each mode and antenna types and gains (testing with the lowest gain antennas is required).

If you have any questions regarding the best methods to ensure your DFS test session is successful to gain compliance, ask our experts or call 800-270-2516.

Scanning Electron Microscopy (SEM), Energy Dispersize X-Ray Analyzer (EDS) Technology now in Anaheim, CA

We are pleased to announce the addition of Scanning Electron Microscopy (SEM) with fully integrated expanded Energy Dispersive X-Ray Analyzer (EDS) at our Anaheim, CA materials testing lab! This capability has been in place at our Baltimore, MD lab for the past year and clients have been thrilled with the high resolution imaging and range of acceleration voltages provided by this research-grade technology.

For those new to the technology, SEM allows for visual observation of an area of interest in a completely different way from that of the naked eye or even normal optical microscopy. The images generated by the SEM show greater contrast between organic-based and metallic-based materials and thus instantly provide a great deal of information about the area being inspected. Simultaneously, EDS can be used to obtain semi-quantitative elemental results  about very specific locations of interest.

Some common uses of SEM and EDS are contamination analysis, solder join evaluation, component defect analysis, inter metallic evaluation, Pb-free reliability, elemental mapping, tin whisker detection, and black pad analysis.

Click here to learn more about SEM/EDS. Contact our Anaheim, CA or Baltimore, MD lab to discuss your programs today.

Shock or Cycling: What’s Right for You?

Using functional test on a PCBA after thermal shock to check for PCB failures

Thermal Testing (without humidity) is typically broken into 2 categories (Shock and Cycling). Thermal Shock is performed using a 2 chamber system that rapidly moves product between Hot and Cold Temperatures. In this test the cold temperatures frequently range from -40C to –55C and the hot temperatures range from 125C to 150C. Thermal Cycling is a single chamber test that gradually moves product from one extreme to the other at 5C to 15C per minute. In this test the cold temperatures can range from -25C to –40C and the hot temperatures range from 65C to 100C. Both tests have the effect of causing expansion of the product and accelerating failures caused by expansion.

Bare PCB’s are tested with optimized daisy chain coupons using thermal shock, as the rate of heat change in the chamber has little to do with the failure mechanisms found in PCBs and the faster transitions significantly shorten cycle times. The extended temperatures often associated with Thermal Shock also provide an additional acceleration factor which can identify potential issues with fewer cycles. PCBs are usually tested for resistance in the chamber at the high temperature where expansion is at its peak.

Assembled PCB’s are typically tested using Thermal Cycling as the rapid transitions associated with thermal shock can cause temperature differentials between the PCB substrate and the attached chips putting strain on the interconnecting solder joints that can lead to premature joint failure that would not happen in real life. In addition, many components are not rated to perform at the high temperatures typically associated with Thermal Shock and can be damaged when exposed to temperatures beyond their rating. In many cases the assembled board is powered and tested or cycled through its operating parameters during the thermal Cycling.

Using functional test of assembled PCBs after Thermal Shock to determine failures in the PCB (cracks and IP Separation) can be problematic. Most PCB’s undergo assembly simulation prior to Thermal Shock so the effect of the process of assembling components onto the PCBA in question is consistent with what would done to a bare PCB facing Thermal Shock testing. The rapid temperature change associated with Thermal Shock can have a detrimental effect on the solder joints of the PCBA due to the fact that the component and PCB absorb or give off heat at different rates. This can result in a CTE mismatch between the component and the PCB that could cause solder joint failure. This effect is typically limited to surface mount components. It is also possible that certain components can be damaged by the temperatures associated with Thermal Shock. In some components it is possible that those temperatures would change electrical properties to a point where they would not function properly. These factors make it a imperative when using this technique to verify and track down the cause each failure seen in functional test. This verification is necessary to ascertain whether the issue is PCB, Solder Joint or Component related failure as any of these would cause a functional test failure.

NTS Volunteers Honored for Contributions to IPC and the Electronics Industry

NTS is proud to announce that our own Debora Obitz, Elizabeth Allison, Renee Michalkiewicz, and Russ Shepherd were among the seventy-five individuals who were presented with Committee Leadership, Special Recognition and Distinguised Committee Service Awards at the IPC Fall Standards Development Committee Meeting this past September in Rosemont, IL.30153606905_3577b56ce1_z

For their contributions to IPC-A-600J, Denise Chevalier, Amphenol Printed Circuits, Inc.; Lorraine Hook, Streamline Circuits; Chris Mahanna, Robisan Laboratory Inc.; Debora Obitz, NTS – Anaheim; and Joey Rios, Massachusetts Institute of Technology, earned a Distinguished Committee Service Award.

Leaders of the 7-31AT IPC-A-600 Technical Training Committee that developed the training and certification Program for IPC-A-600J, Acceptability of Printed Boards, Leo Lambert, EPTAC Corporation and Debora Obitz, NTS – Anaheim, received a Committee Leadership Award.

30118587106_5c59f025c8_zFor their extraordinary contributions to the training and certification program for IPC-A-600J, Elizabeth Allison, NTS – Baltimore and Renee Michalkiewicz, NTS – Baltimore, received a Special Recognition Award. Helena Pasquito, EPTAC Corporation; Russell Shepherd, NTS – Anaheim; and Debbie Wade, Advanced Rework Technology-A.R.T., received a Distinguished Committee Service Award for their contributions to the training and certification program.

For their leadership of the 5-32e Conductive Anodic Filament (CAF) Task Group that developed IPC-9691B, User Guide for the IPC-TM-650, Method 2.6.25, Conductive Anodic Filament (CAF) Resistance and Other Internal Electrochemical Migration Testing, Karl Sauter, Oracle America, Inc. and Russell Shepherd, NTS – Anaheim, earned a Committee Leadership Award.

29524746043_44027d8efe_zDistinguished Committee Service Awards were presented to Douglas Eng, PPG Industries Inc.; Todd MacFadden, Bose Corporation; Renee Michalkiewicz, NTS – Baltimore; and Bhanu Sood, NASA Goddard Space Flight Center, for their contributions to the document revision.

Acoustic Noise Testing Explained

Fremont, CA 10 Mic Acoustic Set Up

NTS 10 Microphone Acoustic Set Up

Acoustic noise testing is the measurement of sound emissions radiating from the equipment under test. In other words, how loud is the equipment?

Why test for acoustic noise?

Many markets and industries require acoustic noise testing to protect the hearing of technicians and users of equipment.

  • Regulatory: OSHA and other international regulatory bodies require that acoustic noise emissions values of many different types of equipment be declared in order for the equipment to be legally sold.
  • Telecommunications: AT&T, Verizon and Telcordia require acoustic noise testing to be performed on products being deployed in central offices, data centers, customer premises and outside plant environments.
  • Medical: Life critical devices need to have a minimum loudness and frequency range for tones and alarms in order to be heard by doctors, nurses and medical technicians.
  • Business/ITE: Equipment that generates annoying or loud tones and buzzes can easily be heard throughout an office environment.
  • Military: Military and defense products are required to undergo acoustic noise testing to prevent hearing loss, permit acceptable speech communication and minimize aural detection by the enemy.

Industry standards which cover acoustic noise testing include: ISO 9296, ISO 7779, ISO 3744, GR-63-CORE, ETSI EN 300 753, IEC 60601, and MIL-STD-1474D (previously MIL-STD-740).

Sound Pressure vs. Sound Power

Sound pressure is the difference in pressure between the instantaneous pressure the audible wave generates and the static pressure of the background environment. This is what your ear actually perceives. The measurement is usually expressed in Pascals or Dynes per square centimeter.

Sound power is the sound pressure taken at multiple points through a surface in space (measurement surface). It is the product of the sound pressure and the particle velocity normal to the surface integrated over the surface. This is a measurement of sound energy over time radiating from a source. The measurement is usually expressed in Watts.

Some standards dictate measurements be expressed in raw sound pressure, and others in sound power. Sound pressure varies between environments based on background noise and reflections. Sound power is a calculation that tries to eliminate the variations that sound pressure is prone to. Using the measurement techniques of ISO 3744 and NTS’s semi-anechoic chambers, consistent reliable sound power values are achievable and can be easily used to compare different product configurations, cooling fan vendors and fan speeds.

A-Weighting & (1/3) Octave Bands

  • A-weighting is a weighting curve applied to sound pressure measurements that replicates the response of the human ear across the entire audible spectrum from 10 Hz to 20 kHz. Most standards require sound pressure measurements to be A-weighted.
  • Octave bands and 1/3 octave bands subdivide the spectrum into different bands to analyze which frequencies in the spectrum have the most sound pressure content. Some standards require specific octave and 1/3 octave bands (such as those closest to human speech) to have lower sound pressure content than others.

10 Microphone Array

NTS Silicon Valley recently upgraded our acoustic noise data acquisition system from a single microphone to a 10 microphone array. This new setup can capture multiple sound pressure measurements or an entire sound power field instantaneously. Our customers can now test many different product configurations in a single day long test session allowing faster troubleshooting and ultimately a quicker time to market.