News
National Physical Laboratory has completed a three-year project investigating the impact of thermal cycling regimes on the shear strength of lead-free solder joints.
The project undertook a comparison of accelerated test regimes for accessing the reliability of solder joints, in particular those made using lead-free solders. Samples were subjected to six different cycling regimes to investigate the effect of thermal excursions, ramp rates and temperature dwells. The most damage to joints per cycle was found to be caused by thermal cycling between 55-125°C, with a 10°C/min ramp rate and 5 minute dwells.
Similar degrees of damage in the lead-free solder joints were experienced from thermal shock regimes with ramp rates in excess of 50°C/min. However, these regimes, although faster to undertake, appeared to cause different crack propagation paths than observed with the thermal cycling regimes, although importantly still remaining within the solder.
Since this is a small difference, thermal shock testing may still be used to differentiate between, or enable ranking of, the effects of changes to materials or processes on the reliability of the solder joints. Hence, if a wide range of conditions are to be tested, a first sift can be completed using thermal shock, with the final work using more typical thermal cycling conditions. The difference between the SAC (95.5Sn3.8Ag0.7Cu) and SnAg (96.5Sn3.5Ag) solder alloy results across all types of cycles showed very little difference in rates of joint degradation.
Dr. Chris Hunt, one of the investigators, said, "One of the major findings to come out of this work is that the thermal shock cycles do produce a failure that is different to ordinary thermal cycles, but the failure is still in the solder, hence it gives us enough confidence to use it as a process to sort out reliability on a range of assemblies. It requires us to use the more usual thermal cycles which are slower ramp and dwell for final qualification, but the thermal shock is definitely a useful tool in getting through lots of different assemblies and evaluating & ranking reliability. The thermal shock cycle will typically be at least a third of the time, so you will get there more than three times quicker. So, if you are cycling, typically up to 2000 cycles, significant time can be saved—down from two months to two weeks."
For more information contact Dr. Chris Hunt: chris.hunt@npl.co.uk.
Copyright 2004, UP Media Group. All rights reserved.
Aegis Industrial Software Corp. (Horsham, PA), a provider of manufacturing productivity software, has announced that the Key Electronics (New Albany, IN) has purchased the entire scope of Aegis software to support all factory information management from new product introduction (NPI) through manufacturing execution, quality, traceability and line monitoring. The electronic manufacturing services (EMS) provider has selected Aegis software to deliver efficient management of data from the factory office to the factory floor and from end-to-end of the product lifecycle.
Tom Hardy, Key Electronics president, said, "Our decision to partner with Aegis is the result of a deliberate effort to increase efficiencies and productivity for our customers as we grow as well as maintain aggressive quality levels....and demonstrates our commitment to leading edge technology, improved processes and total commitment to be the choice for original equipment manufacturers (OEMs) in the high mix/low volume marketplace."
Jason Spera, chief executive officer of Aegis, said, "Key Electronics and Aegis are both recipients of our industry's Service Excellence Awards, sponsored by Circuits Assembly. By standardizing factory-wide on the entire Aegis system, Key Electronics has invested to even further enhance their quality and the service they provide their customers. Both companies share a common vision; a single software platform spanning NPI to MES to the real-time machine data, and out to management and customer portals delivers real business advantage."
The deployment of Aegis software at Key Electronics provides a single source for all NPI engineering operations, including bill of materials (BOM) validation and program generation cross-line, and a single-database solution for MES and factory execution analysis. Quality data collection, automated repair and product tracking is automated through interactive and visual Web interfaces throughout the factory floor. The system joins this information to real-time data streaming from machines across the entire line—not just surface-mount placement—for real process visibility and traceability.
Copyright 2004, UP Media Group. All rights reserved.
Preco Electronics (Morton, IL), a provider of electronic manufacturing services, received ITM Process Certification for Class 2, Electronics Assembly.
ITM Consulting's (Durham, NH) principal consultants, Jim Hall and Phil Zarrow, conducted a series of operations and process audits and certified that the materials, equipment, processes and personnel comprising the Preco Electronics facility have met the standards set forth by ITM and represent best practices for the assembly of Class 2 electronic products. ITM determined that the printed circuit board (PCB) assembly operation within the Preco's Morton facility is capable of producing high-quality printed circuit assemblies in accordance with IPC-A-610, Class 2, Acceptability of Printed Circuit Boards.
Jim Lanigan, director of operations and engineering at Preco, said, "The significance of attaining ITM Certification is that it allows our customers to benefit from our sophisticated degree of technology for EMS products coupled with a high commitment to quality, all while enjoying the service level a world-class Tier 3 EMS provider can offer. The team at ITM conducted the audit and noted areas requiring enhancement or improvement. Our engineering, quality and production staff made the modifications and we attained certification."
ITM president, Phil Zarrow, said, "Preco's certification should help dispel the myth that only a Tier 1 EMS provider can have a world-class facility. Preco is the first North American EMS provider to receive ITM Assembly Process Certification."
PCB Assembly and PCB Fabrication Process Certifications are patent pending services provided exclusively through ITM Consulting.
Copyright 2004, UP Media Group. All rights reserved.
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