Technical Library | 2015-08-13 15:52:40.0
Pad cratering has become more prevalent with the switch to lead free solders and lead free compatible laminates. This mainly is due to the use of higher reflow temperature, stiffer Pb-free solder alloys, and the more brittle Pb-free compatible laminates. However, pad cratering is difficult to detect by monitoring electric resistance since pad cratering initiates before an electrical failure occurs. Several methods have been developed to evaluate laminate materials' resistance to pad cratering. Pad-solder level tests include ball shear, ball pull and pin pull. The detailed methods for ball shear, ball pull, and pin pull testing are documented in an industry standard IPC-9708. Bansal, et al. proposed to use acoustic emission (AE) sensors to detect pad cratering during four-point bend test. Currently there is an industry-working group working on test guidelines for acoustic emission measurement during mechanical testing.
Technical Library | 2015-08-20 15:18:38.0
Increasing system integration and component densities continue to significantly reduce the opportunity to access nets using standard test points. Over time the size of test points has been drastically reduced (as small as 0.5 mm in diameter) but current product design parameters have created space and access limitations that remove even the option for these test points. Many high speed signal lines have now been restricted to inner layers only. Where surface traces are still available for access, bead probe technology is an option that reduces test point space requirements as well as their effects on high speed nets and distributes mechanical loading away from BGA footprints enabling test access and reducing the risk of mechanical defects associated with the concentration of ICT spring forces under BGA devices. Building on Celestica's previous work characterizing contact resistance associated with Pr-free compatible surface finishes and process chemistry; this paper will describe experimentation to define a robust process window for the implementation of bead probe and similar bump technology that is compatible with standard Pb-free assembly processes. Test Vehicle assembly process, test methods and "Design of Experiments" will be described. Bead Probe formation and deformation under use will also be presented along with selected results.
Technical Library | 2019-05-06 23:04:05.0
The temperature and humidity test chamber simulate the temperature and humidity, so there are a lot of things customers shoud notice in the process of use, although there is detailed instruction when purchasing the equipment. But some users just know how the device works and start using it. This is very easy to cause problems in the use of the equipment, so Symor intends to describe the safety details during the use of temperature and humidity chamber. 1. Before the test, determine if the sample contains flammable and explosive substances to avoid combustion or explosion during the test. Of course, also make sure there is no flammable and explosive material around the test equipment, otherwise it may cause fire and other accidents. 2, Do not open the chamber door to operate during the experiment, or the gas in the studio may cause the operator to burn and so on. 3. At the end of the test or at the time of regular cleaning of the test chamber, power off the equipment to avoid electrocution accidents. Also, when cutting off the equipment power, pull the power cord to pull out the plug, otherwise it may lead to a rupture of the power cord and so on. You can contact manufacturers if there are some places you donnot understand, do not dismantle and repair the temperature and humidity test chamber without authorization, otherwise it may lead to more serious problems.
Technical Library | 2019-05-08 01:46:32.0
IPX9K Rain Spray Test Chamber(high Pressure high temperature water jet) simulates the use of pressure washer steam cleaning onto the enclosure, It is recognised as the harshest of all ingress protection tests. However the requirement is becoming more prevalent across many industries. Test method for IPX9K : Make sure the water temperature inside the water tank +80°C, water flow rate with 14L-16L per min, water pressure: 8000 Kpa -10000 Kpa (80–100 bar) at distance of 100mm~ 150mm, The test duration is 30 seconds in each of 4 angles, total spray testing time is 2 minutes. IPX9K rain test chamber applicable standards: IEC 60529 – Degrees of protection provided by enclosures (IP Code).Here is working principle in picture. Application: It is mainly suitable for testing the performance of shell and seal of electrical and electronic parts, automobile parts and seals under the condition of dripping rain to prevent Rain Water from permeating or working after drizzling.
Technical Library | 2016-11-30 15:53:15.0
The use of microvias in Printed Circuit Boards (PCBs) for military hardware is increasing as technology drives us toward smaller pitches and denser circuitry. Along with the changes in technology, the industry has changed and captive manufacturing lines are few and far between. As PCBs get more complicated, the testing we perform to verify the material was manufactured to our requirements before they are used in an assembly needs to be reviewed to ensure that it is sufficient for the technology and meets industry needs to better screen for long-term reliability. The Interconnect Stress Testing (IST) protocol currently used to identify manufacturing issues in plated through holes, blind, or buried vias are not necessarily sufficient to identify problems with microvias. There is a need to review the current IST protocol to determine if it is adequate for finding bad microvias or if there is a more reliable test that will screen out manufacturing inconsistencies. The objective of this research is to analyze a large population of PCB IST coupons to determine if there is a more effective IST test to find less reliable microvias in electrically passing PCB product and to screen for manufacturing deficiencies. The proposed IST test procedure will be supported with visual inspection of corresponding microvia cross sections and Printed Wiring Assembly (PWA) acceptance test results. The proposed screening will be shown to only slightly affect PCB yield while showing a large benefit to screening before PCBs are used in an assembly.
Technical Library | 2020-12-10 15:49:40.0
Electronic assemblies should have longer and longer service life. Today there are partially demanded 20 years of functional capability for electronics for automotive application. On the other hand, smaller components, such as resistors of size 0201, are able to endure an increasing number of thermal cycles until fail of solder joints, so these are tested sometimes up to 4000 cycles. But testing until the end of life is essential for the determination of failure rates and the prognosis of reliability. Such tests require a lot of time, but this is often not available in developing of new modules. A further acceleration by higher cycle temperatures is usually not possible, because the materials are already operated at the upper limit of the load. However, the duration can be shortened by the use of liquids for passive tests, which allow faster temperature changes and shorter dwell times because of better heat transfer compared to air. The question is whether such tests lead to comparable results and what failure mechanisms are becoming effective. The same goes for active temperature cycles, in which the components itself are heated from inside and the substrate remains comparatively cold. This paper describes the various accelerated temperature cycling tests, compares and evaluates the related degradation of solder joints.
Technical Library | 2013-04-04 15:28:39.0
This paper will outline and define what requirements must be adhered to for the OEM community to truly achieve the IPC class product from the Electrical Test standpoint. This will include the test point optimization matrix, Isolation (shorts) parameters and Continuity (opens) parameters. This paper will also address the IPC Class III/A additional requirements for Aerospace and Military Avionics. The disconnect exists between OEMs understanding the requirements of their specific IPC class design versus the signature that will be presented from their design. This results in many Class III builds failing at Electrical Test... First published in the 2012 IPC APEX EXPO technical conference proceedings
Technical Library | 2012-12-14 14:28:20.0
This paper examines the potential failure mechanisms that can damage modern lowvoltage CMOS devices and their relationship to electrical testing. Failure mechanisms such as electrostatic discharge (ESD), CMOS latch-up, and transistor gate oxide degradation can occur as a result of electrical over-voltage stress (EOS). In this paper, EOS due to electrical testing is examined and an experiment is conducted using pulsed voltage waveforms corresponding to conditions encountered during in-circuit electrical testing. Experimental results indicate a correlation between amplitude and duration of the pulse waveform and device degradation due to one or more of the failure mechanisms.
Technical Library | 2014-11-18 23:59:30.0
Performance degradation of packaging material is an important reason for the lifetime reduction of LED. In order to understanding the failure behavior of packaging material, silicone and phosphor were chosen to fabricate LED samples within which an aging test at 125℃ was performed. The result of online luminance measurement showed that LED samples with both silicone and phosphor had the highest luminance decay rate among all test samples because the carbonization of silicone and the consequent outgassing reduced the luminance quickly. The result of the luminance variance with test time was analyzed and an exponential decay model was developed with which the lifetime of LED under high temperature could be estimated.
Technical Library | 2015-02-19 16:54:34.0
Pad cratering is an important failure mode besides crack of solder joint as it’ll pass the regular test but have impact on the long term reliability of the product. A new pin pull test method with solder ball attached and positioning the test board at an angle of 30º is employed to study the strength of pad cratering. This new method clearly reveals the failure mechanism. And a proper way to interpret the finite element analysis (FEA) result is discussed. Impact of pad dimension, width and angle of copper trace on the strength is included. Some findings not included in previous research could help to guide the design for better performance
