Standard of Excellence: The Human Touch in an Automated World
The Government Circuit: Navigating New Trade Headwinds and New Partnerships
Global Sourcing Spotlight: How to Evaluate Supplier Capabilities Worldwide
Solder Paste Stencil Design for Optimal QFN Yield and Reliability
April 29, 2015 | Ben Gumpert, Lockheed MartinEstimated reading time: 13 minutes
These two components were selected based on results of previous testing. The QFN68 package has a very high die to body size ratio, and has performed relatively poorly in other thermal cycle tests. The QFN44 package, however, has a low die to body size ratio, and in a previous test, there were no failures after 2520 thermal cycles. This testing will investigate the ability to improve results on a ‘poorly’ performing part, as well as the potential for reducing performance on a ‘robust’ part.
To develop an idea about how the chosen experimental parameters and variation would affect test results, a simulation software package was used to predict the outcomes of the testing. Figure 2 shows the results of that simulation and the prediction of the average thermal cycle survival period for the QFN68 package at the solder joint heights to be used in this test. Results of previous testing were used as a baseline to fit the prediction results to the test vehicle used.
A 5 mil stencil was used for solder paste application with apertures similar to those shown in Figure 3, but which varied by location on the board to control the volume of solder deposited at different sites across the assembly. The volume of solder was controlled by the number and size of apertures on the center pad of the QFN/BTC footprint. The volume of solder applied to the perimeter pins was also adjusted, with the objective of creating similar solder joints on all component locations (i.e. solder joint with the same amount of toe wetting and with similar fillet shape), although the height of these joints was different from location to location. Ten different aperture patterns were used for the QFN44 package, and 14 different aperture patterns were used for the QFN68 package. Reduction of solder on the center pad ranged from 10% to 90%. These values are outside of both the minimum and maximum recommendations, but are being evaluated to observe potential trends.
Page 2 of 4
Share on:
Testimonial
"We’re proud to call I-Connect007 a trusted partner. Their innovative approach and industry insight made our podcast collaboration a success by connecting us with the right audience and delivering real results."
Julia McCaffrey - NCAB GroupSuggested Items
More Than a Competition: Instilling a Champion's Skill in IPC Masters China 2025
09/01/2025 | Evelyn Cui, Global Electronics Association—East AsiaNearly 500 elite professionals from the electronics industry, representing 18 provinces and municipalities across China, competed in the 2025 IPC Masters Competition China, March 26–28, in Pudong, Shanghai. A total of 114 contestants advanced to the practical competition after passing the IPC Standards Knowledge Competition. Sixty people competed in the Hand Soldering and Rework Competition (HSRC), 30 in the Cable and Wire Harness Assembly Competition (CWAC), and 24 in the Ball Grid Array/Bottom Termination Components (BGA/BTC) Rework Competition.
Indium Promotes Huang to Senior Manager, Marketing Communications
08/28/2025 | Indium CorporationWith its commitment to innovation and growth through employee development, Indium Corporation announces the promotion of Jingya Huang to Senior Manager, Marketing Communications, to continue to lead the company’s branding and promotional efforts.
Rehm Academy Expands Its Training Program
08/28/2025 | Rehm Thermal SystemsThe demands on modern industrial companies and employees continue to rise, and therefore, the topic of further education is becoming increasingly important today.
MacDermid Alpha Awarded for Innovation: Driving Process Optimization and Efficiency with Major Indian EMS Provider
08/28/2025 | MacDermid Alpha Electronics SolutionsMacDermid Alpha Electronics Solutions, a leading global supplier of integrated materials for the electronics industry, is recognized by one of India’s top EMS providers, Syrma SGS, with an award for innovation that advanced process optimization, enhanced operational efficiency, and yield gains.
Integrated Solutions for Board-level Reliability: A Smarter Path Forward
08/27/2025 | Alan Gardner, MacDermid Alpha Electronics SolutionsIn today’s electronics manufacturing landscape, reliability is no longer just a benchmark but a business imperative. As industries such as automotive, aerospace, and high-performance computing (HPC) push the boundaries of innovation, the demand for dependable board-level performance under extreme conditions has never been greater.