Printed Circuit Design & Fab - August 2008 - (Page 37)

outSourcinG fiGurE 1. Supplier score for quality systems audit. fiGurE 2. hDI PCB. fiGurE 3. ALIvh PCB. and quality system. The supplier was then certified for production based on a minimum score of 90% or above as shown in fiGurE 1. Most manufacturers in Asia have some percentage of their operations outsourced. It is important to understand the manufacturing process of your product or technology, and to also survey any subcontract operations during the audit since process controls implemented there also affect the end product. In this case, all action items generated from the audit were closed within five working days. It is also important to follow up with annual quality audits. Product Qualification. The board assembly process that qualified used a double-sided, surface-mount assembly soldering of BGA (ball grid array) packages, connectors, chip resistors, capacitors, diodes and other components. Assembly reflow took place using convection air at a peak temperature of 244°C. The assembly solder paste used was SAC 305 (tin/silver/ copper) no-clean version.3 Cross-sections were performed on BGA packages and other components to evaluate the quality of the solder joints and ensure compliance to IPC 610 – Rev D for leaded packages and IPC 7095 for BGA packages. Microvia integrity was also evaluated with cross-sectional analysis. Cross-sections showed acceptable solder joints and no degradation of the microvias.3, 4 The qualification process was conducted using product build for a phone program and cross-sectional analysis, and reliability testing per IPC 9701.5 Temperature and humidity tests were conducted at 85°C at 85% relative humidity for 500 hours, and thermal shock testing was conducted from AUGUST 2008 –25°C to +125°C at 20 minute dwell for 500 cycles. fiGurE 2 shows crosssections for HDI board assembly post reflow, and fiGurE 3 shows ALIVH PCB assembly post reflow. Rework Process Surface-mount packages were reworked using hot-air soldering tools, and BGA packages were reworked with hot air using controlled ramp/soak profile. The main concern was damage to microvia connections and PCB pads during component removal and reattach. Component rework was performed two times on the leaded packages and one time on the BGAs. All packages survived rework. There was no damage to PCB pads or blistering of the solder mask during rework. No damage was seen on microvia connections. fiGurES 4 and 5 show cross-sections of HDI and ALIVH PCB post rework after 500 thermal shock cycles. Production DPPM Issues There were two types of production rejects. Cosmetic rejects were lots rejected at the incoming IQC inspection and functional rejects where the printEd circuit dEsign & faB 37 http://www.chemcut.net http://www.chemcut.net

Table of Contents Feed for the Digital Edition of Printed Circuit Design & Fab - August 2008

Printed Circuit Design & Fab - July 2008 Contents Our Line Market Watch Around the World Happenings ROI Tip Jar Software Performance Interconnect Strategies Final Finish Forum Product Development Challenges in a Global Market Innovative Modeling Supports Co-Design of the Power Supply Chain, Part 2 Low-Loss Fluoropolymer Copper Clad Laminate Qualifying PCBs Outsourced in Asia Copper Plating and Microvia Fill for Advanced PCBs Off the Shelf Marketplace Ad Index BGA Bulletin

Printed Circuit Design & Fab - August 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.