Technical Library | 2012-11-27 14:06:48.0
Quality managers and line supervisors are routinely tasked with the responsibility of ensuring that the hand soldering process is under control. The method most commonly used is to measure the idle tip temperature of the soldering station and to use this reading as a benchmark of system compliance. This method, although popular is now being seriously questioned by many industry professionals as being irrelevant in qualifying true system process control. This document aims to present a practical view of what factors are important for successful hand soldering and to suggest an alternative procedure for qualification that is simple, repeatable and directly related to the effectiveness of the soldering station.
Technical Library | 2022-06-20 21:01:37.0
We've been doing a lot of print testing in our lab. In our first set of published results, "The Impact of Reduced Solder Alloy Powder Size on Solder Paste Print Performance1" from IPC/APEX 2016, we revealed a hierarchy of input variables to maximize solder paste transfer efficiency and minimize variation. In that study, we used a fully-optioned stencil as part of the equipment set. In order to tease out the data we were looking for, we could not lose critical information to the noise of stencil-induced variations.
Technical Library | 2010-03-04 18:11:53.0
While the electronics manufacturing industry has been occupied with the challenge of RoHS compliance and with it, Pb-free soldering, established trends of increasing functionality and miniaturization have continued. The increasing use of ultra-fine pitch and area-array devices presents challenges in both printing and flux technology. With the decrease in both the size and the pitch of said components, new problems may arise, such as head-in-pillow and graping defects
Technical Library | 2021-09-21 20:36:45.0
The present paper gives an overview of surface failures, internal nonconformities and solders joint failures detected by microscopic analysis of electronic assemblies. Optical microscopy (stereomicroscopy) and Fourier-Transform- Infrared (FTIR) microscopy is used for documentation and failure localization on electronic samples surface. For internal observable conditions a metallographic cross-section analysis of the sample is required. The aim of this work is to present some internal and external observable nonconformities which frequently appear in electronic assemblies. In order to detect these nonconformities, optical microscopy, cross section analysis, FTIR-microscopy and scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) were used as analytical techniques.
Technical Library | 2014-05-12 15:32:17.0
The issue of lead-free soldering has piqued a great deal of interest in the electronics assembly industry as of late. What was once an issue that seemed too far away to worry about has become a pressing reality. In order to avoid confusion, last minute panic, and a misunderstanding of how the issue of lead-free soldering will affect the industry and individuals users of solders, it is necessary for all suppliers and assemblers to become educated in this matter.
Technical Library | 2019-10-10 00:26:28.0
Voids are a plague to our electronics and must be eliminated! Over the last few years we have studied voiding in solder joints and published three technical papers on methods to "Fill the Void." This paper is part four of this series. The focus of this work is to mitigate voids for via in pad circuit board designs. Via holes in Quad Flat No-Lead (QFN) thermal pads create voiding issues. Gasses can come out of via holes and rise into the solder joint creating voids. Solder can also flow down into the via holes creating gaps in the solder joint. One method of preventing this is via plugging. Via holes can be plugged, capped, or left open. These via plugging options were compared and contrasted to each other with respect to voiding. Another method of minimizing voiding is through solder paste stencil design. Solder paste can be printed around the via holes with gas escape routes. This prevents gasses from via holes from being trapped in the solder joint. Several stencil designs were tested and voiding performance compared and contrasted. In many cases voiding will be reduced only if a combination of mitigation strategies are used. Recommendations for combinations of via hole plugging and stencil design are given. The aim of this paper is to help the reader to "Fill the Void."
Technical Library | 2015-02-12 16:57:56.0
Electronic systems are known to be affected by the environmental and mechanical conditions, such as humidity, temperature, thermal shocks and vibration. These adverse environmental operating conditions, with time, could degrade the mechanical efficiency of the system and might lead to catastrophic failures.The aim of this study is to investigate the mechanical integrity of lead-free ball grid array (BGA) solder joints subjected to isothermal ageing at 150°C for up to 1000 hours. Upon ageing at 150°C the Sn-3.5Ag solder alloy initially age-softened for up to 200 hours. This behaviour was linked to the coarsening of grains. When aged beyond 200 hours the shear strength was found to increase up to 400 hours. This age-hardening was correlated with precipitation of hard Ag3Sn particles in Sn matrix. Further ageing resulted in gradual decrease in shear strength. This can be explained as the combined effect of precipitation coarsening and growth of intermetallic layer. The fractured surfaces of the broken solder balls were also investigated under a Scanning Electron Microscope. The shear failures were generally due to ductile fractures in bulk solders irrespective of the ageing time.
Technical Library | 2024-01-08 18:36:01.0
The following aims lie behind the investigations described: The circuit board is an integrated structure made of metal and plastic. Like most integrated components enclosed in plastic, it absorbs water. When it is rapidly heated as, for example, in soldering technology temperature processes, it is a well known fact that the water will evaporate abruptly, leading to destruction. It is therefore essential that the circuit board be dried before these soldering processes. Circuit board manufacturers are extremely hesitant at providing instructions on drying their circuit boards. Information from the ZVEI [1] should also be regarded critically. The cardinal problem is the high temperature which is recommended for baking. If this is applied, the result is often de-lamination and distortion of the circuit boards. Corrosion and the formation of intermetallic phases of the metallic surfaces are also to be expected. The following investigates whether gentle drying at 45°C or 60°C and at low relative humidity achieves the same result as baking at high temperatures. The industry provides novel dry cabinets which are suitable for rapid drying at relative humidities below one percent.
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