Component Assessment

“Compliance, Risk and Cost of Ownership Comparisons for Medical Device Sterile Products, Materials and Components Continuous Monitoring”
Author: Ken Appel; ken.appel@vaisala.com
Abstract: A guide to evaluating costs of monitoring critical environments while controlling risk factors. Six different modalities used in medical device and medical products’ materials and components industries for continuous monitoring – chart recorders, standalone data loggers, wired LAN networks with UPS backups, wired LAN networks using Power over Ethernet; WiFi; and Wireless Mesh – are systematically explained and compared in terms of costs of ownership and risks of non-compliance and loss in the context of today’s regulatory environment. (Company white paper, November 2010)

Environmental Management

“PVC-Based Composite Material Containing Recycled Non-Metallic Printed Circuit Board (PCB) Powders”
Authors: X.J. Wang, et al.
Abstract: A study of the use of non-metallic powders obtained from comminuted recycled paper-based PCBs as an additive to polyvinyl chloride substrate. The physical properties of the non-metallic PCB (NMPCB) powders were measured, and the morphological, mechanical and thermal properties of the NMPCB/PVC composite material were investigated. Results show that recycled NMPCB powders, when added below a threshold, tended to increase the tensile strength and bending strength of PVC. When 20 wt% NMPCB powders (relative to the substrate PVC) of an average diameter of 0.08 mm were added, the composite tensile strength and bending strength reached 22.6 MPa and 39.83 MPa, respectively, representing 107.2% and 123.1% improvement over pure PVC. The elongation at break of the composite material reached 151.94% of that of pure PVC, while the Vicat softening temperature of the composite material did not increase significantly compared to pure PVC. The results suggest that paper-based NMPCB powders, when used at appropriate amounts, can be effective for toughening PVC. (Journal of Environmental Management, December 2010)

Stencil Manufacture

“System for Laser Micromachining of Thin Metal Foils”
Author: Robert Barbuchaa, Marek Kocik and Jerzy Mizeraczyk; brobert@imp.gda.pl.
Abstract: A prototype of a laser system for micromachining of the materials (ULMM) is presented. This system is used for metal foils cutting, in particular for cutting stencils used in printing solder paste for PCB assembly. The system consists of prototype Nd:YAG laser; motorized deflection mirror; precise X-Y table with pneumatic metal foil holders; and control unit with custom software. A deflection mirror is used to obtain a trapezoidal shape of cutting edges, which is significant for PCB manufacturing. The X-Y table is based on modern planar motors, which have maximum velocity of 1 m/s at 20g acceleration. This system is capable of cutting holes with diameters of 10 µm and precise trepanation of the holes with diameters of 50 µm. (XVII International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers, April 2009)

Surface Finishes

“Effect of PCB Surface Finishes on Lead-Free Solder Joint Reliability”
Authors: Xu Zheng, Hongfeng Ran, Lei Wang, Hao Kou, Yexiang Ning, Bei Wang, Xian Lin, and Zuyao Liu
Abstract: The reliability of SnAg3.0Cu0.5 (SAC 305) solder joints with four kinds of PCB surface finishes was studied under isothermal aging at 125°C, including electroless nickel and immersion gold, organic solderability preservative, immersion silver and immersion tin. Their intermetallic compound composition and morphology were investigated by SEM/EDX, and the crystallographic features of IMC determined by XRD. Then the evolution of the microstructure of solder joints under isothermal aging was reviewed. Results showed the IMC grains on ImSn pad were unequal, with larger length/diameter ratio, and had different crystal orientations from that on OSP and ImAg pads. The high content of phosphorus in ENIG resulted in the emergence of phosphorus-rich and Ni3SnP multilayer after aging. Moreover, the mechanical properties of the solder joints with four PCB surface finishes were also studied via QFP pull test and high-speed solder ball shear test (HSSBS). Combined with the fracture analysis and mechanical test results of solder joints, it was found that the differences of failure modes and reliability performance were related to solder joint microstructure. ENIG pad showed poor reliability performance in HSSBS test due to the presence of phosphorus-rich/Ni3SnP multilayer structure after aging and interface micro-crack defect. Last, the electrical properties of different solder joints were evaluated by comparing their electrical resistivity. Owing to different composition and IMC crystal orientation, the resistivity of ImSn and ENIG pads after aging increased, while those of OSP and ImAg pads decreased. (Journal of Surface Mount Technology, October - December 2010, vol. 23, no. 4)

This column provides abstracts from recent industry conferences and company white papers. Our goal is to provide an added opportunity for readers to keep abreast of technology and business trends.

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