-
- News
- Books
Featured Books
- smt007 Magazine
Latest Issues
Current IssueBox Build
One trend is to add box build and final assembly to your product offering. In this issue, we explore the opportunities and risks of adding system assembly to your service portfolio.
IPC APEX EXPO 2024 Pre-show
This month’s issue devotes its pages to a comprehensive preview of the IPC APEX EXPO 2024 event. Whether your role is technical or business, if you're new-to-the-industry or seasoned veteran, you'll find value throughout this program.
Boost Your Sales
Every part of your business can be evaluated as a process, including your sales funnel. Optimizing your selling process requires a coordinated effort between marketing and sales. In this issue, industry experts in marketing and sales offer their best advice on how to boost your sales efforts.
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - smt007 Magazine
Top 10 Countdown: Most-Read EMS Tech Tuesday Articles of 2010
December 28, 2010 | I-Connect007Estimated reading time: 3 minutes
The past year was a great one when it came to the techical content offered by SMT Online. The I-Connect007 editors have compiled the top 10 Tech Tuesday articles on technology developments and key issues in the EMS industry for 2010.Here we go...
At the #10 spot, Copper Tin Intermetallic Crystals' Role in Formation of Microbridges Between Leads, Part I: Unless the solder in a reservoir is regularly changed, the dissolved copper reaches a point of saturation, forming orthorhombic Cu6Sn5 crystals. Solder drawn from a saturated pot can solidify into joints whose surface finish exhibits many needle-like metallic protrusions. This paper documents failures caused by this phenomenon and identifies the cause of the problem and rework techniques used to prevent its occurrence.At #9, Solder Joint Reliability Analysis and Testing of a Dual-Row QFN: Dual-row QFN designs help bridge the gap between conventional QFN packages and BGAs. They enable a higher I/O count per area of single-row QFN packages and they maintain similar costing due to the lead frame-based technology. This paper focuses on the board-level solder joint reliability of a 28-lead dual-row QFN package.At #8, Closed-Form, Strain-Energy-Based Acceleration Factors for Thermal Cycling of Lead-Free Assemblies: A framework has been developed for a new type of closed-form AF model for thermal cycling of soldered assemblies. The AF model is strain-energy-based, and was applied to SAC305, SAC387/396/405 and near-eutectic SnPb assemblies. The advantages and limitations of this model compared to other approaches in the reliability engineer's toolbox are also discussed.At #7, Selective Electroless Nickel and Gold Plating of Individual Integrated Circuits for Thermocompression Gold Stud Bump Flip-Chip Attachment: To overcome the intermetallic problem at the IC's aluminum-metallized bonding pads, an electroless nickel and gold plating process was developed for making a gold-bondable diffusion barrier for use on individual, unpackaged silicon ICs--a topic addressed by this paper from APL.At the #6 spot, Electroless Ni/Electroless Pd/Immersion Au/Electroless Au (ENEPIGEG) Plating Process For Gold Wire Bonding on Organic Package Substrates: This study examines the wire bonding reliability of electroless gold plating after heat treatment. Results indicate that in the ENIGEG process, the electroless Ni under the immersion Au/electroless Au diffused onto the surface of the gold plating by heat treatment and changed to nickel oxide, resulting in the prevention of wire bonding between the gold wire and the gold plating and a decrease in bonding strength.At #5, Step Stencil Design When 01005 and 0.3 mm Pitch uBGAs Coexist with RF Shields: A "Two-Print Stencil Process" is an effective solution to print solder paste when different paste heights are required--spacing between apertures requiring different heights can be as small as 380 um (15 mils). It has been demonstrated that the depth of the relief pocket in the second print stencil can be as low as 25 um (1 mil) more than the thickness of the first print stencil.At #4, Counterfeit Electronics: Threats, Risks and Prevention Practices: Product counterfeiting accounts for more than 8% of global merchandise trade and is equivalent to as much as $600 billion in lost sales. Counterfeit items used in computers, aircraft, cars, telecommunications and medical devices are a serious risk for national security, health and safety.At #3, Creep Corrosion of OSP and ImAg PWB Finishes: The effect of post-reflow cleaning processes on creep corrosion are discussed in this paper from Alcatel-Lucent.The authors examine a laboratory MFG test that replicates field creep corrosion. Comparisons of creep corrosion susceptibility between OSP and ImAg PWB surface finishes are also made.At the #2 spot, Effects of Storage Procedures and Bake Out on Solderability of Immersion Silver-Coated PCBs: Authors from Sandia National Laboratories investigate the solderability of current immersion Ag technology after exposure to conditions that simulate long-term storage followed by bake out environments prior to actual reflow assembly.And, finally, at the #1 spot for 2010, Drop Test: Lead-Free Board After Assembly and Rework: This award-winning paper from APEX 2010 examines how the transition to lead-free materials in the general electronics industry significantly impacts the mechanical reliability of solder joint interconnects, a fact widely recognized by the consumer electronics industry.