Technical Library | 2023-09-13 13:04:47.0
SMT nozzle cleaning machines are essential for ensuring the quality and reliability of SMT assembly processes. These machines remove contaminants and debris from SMT nozzles, which can cause defects and reliability issues.
Technical Library | 2010-06-10 21:01:48.0
This paper researches the effectiveness of the R.O.S.E. cleanliness testing process for dissolving and measuring ionic contaminants from boards soldered with no-clean and lead-free flux technologies.
Technical Library | 2022-03-16 19:48:18.0
Dendrites, Electrochemical Migration (ECM) and parasitic leakage, are usually caused by process related contamination. For example, excess flux, poor handling, extraneous solder, fibers, to name a few. One does not normally relate these fails with environmental causes. However, creep corrosion is a mechanism by which electronic products fail in application, primarily related to sulfur pollution present in the air.1 The sulfur reacts with exposed silver, and to a lesser extent, exposed copper. This paper will explore various aspects of the creep corrosion chemical reaction
Technical Library | 2023-02-13 18:56:42.0
This paper describes the results of an intensive whisker formation study on Pb-free assemblies with different levels of cleanliness. Thirteen types of as-received surface-mount and pin-through-hole components were cleaned and intentionally contaminated with solutions containing chloride, sulfate, bromide, and nitrate. Then the parts were assembled on double-sided boards that were also cleaned or intentionally contaminated with three fluxes having different halide contents. The assemblies were subjected to high-temperature/high-humidity testing (85_C/85% RH). Periodic examination found that contamination triggered whisker formation on both exposed tin and solder fillets. Whisker occurrence and parameters depending on the type and level of contamination are discussed. Cross-sections were used to assess the metallurgical aspects of whisker formation and the microstructural changes occurring during corrosion.
Technical Library | 2023-04-17 21:17:59.0
The purpose of this paper is to evaluate and compare the effectiveness and sensitivity of different cleanliness verification tests for post soldered printed circuit board assemblies (PCBAs) to provide an understanding of current industry practice for ionic contamination detection limits. Design/methodology/approach – PCBAs were subjected to different flux residue cleaning dwell times and cleanliness levels were verified with resistivity of solvent extract, critical cleanliness control (C3) test, and ion chromatography analyses to provide results capable of differentiating different sensitivity levels for each test. Findings – This study provides an understanding of current industry practice for ionic contamination detection using verification tests with different detection sensitivity levels. Some of the available cleanliness monitoring systems, particularly at critical areas of circuitry that are prone to product failure and residue entrapment, may have been overlooked. Research limitations/implications – Only Sn/Pb, clean type flux residue was evaluated. Thus, the current study was not an all encompassing project that is representative of other chemistry-based flux residues. Practical implications – The paper provides a reference that can be used to determine the most suitable and effective verification test for the detection of ionic contamination on PCBAs. Originality/value – Flux residue-related problems have long existed in the industry. The findings presented in this paper give a basic understanding to PCBA manufacturers when they are trying to choose the most suitable and effective verification test for the detection of ionic contamination on their products. Hence, the negative impact of flux residue on the respective product's long-term reliability and performance can be minimized and monitored effectively.
Technical Library | 2015-02-05 20:25:41.0
In the past 20 yrs the solvent industry has gone through a great deal of change. In the early 1990s, CFC-113 and 1,1,1-trichloroethane were the workhorses of the industry. The Montreal Protocol to phase-out substances that deplete the Earth's protective Ozone Layer was implemented in the mid 1990s. After phase-out of the CFC solvents, the solvent industry fragmented to a variety of cleaning solutions. The electronics industry was a large user of CFC solvents and many of these applications changed to aqueous based cleaners (...) But those alternatives are now facing various problems: e.g. aqueous based cleaners use a lot of energy, require long drying times, use equipment that requires frequent maintenance, and require a large footprint; no-clean fluxes leave flux residues; and trichloroethylene and n-propyl bromide have toxicity issues. In response to these serious issues newer solvents and blends are being introduced in the marketplace
Technical Library | 2019-07-24 23:55:32.0
Voiding is a key concern for components with thermal planes because interruptions in Z-axis continuity of the solder joint will hinder thermal transfer. When assembling components with solder paste, there is a high propensity for voiding due to the confined nature of the solder paste deposits under the component. Once reflowed, many factors contribute to the amount of voiding in a solder joint such as the reflow profile, designs of the component, board and stencil, and material factors. This study will focus on the solder paste alloy and flux combination as well as profile and board surface finishes.
Technical Library | 1999-05-07 10:47:00.0
White residue remaining after cleaning circuit board assemblies can be caused by a variety of chemicals and reactions. Rosin and water-soluble fluxes, circuit board resins and epoxies, component materials and other contamination all contribute to this complex chemistry. This paper discusses many of the sources of the residues that seem to be an ever-increasing occurrence.
Technical Library | 2021-08-25 16:28:36.0
In this study, a Sn–Bi composite solder paste with thermosetting epoxy (TSEP Sn–Bi) was prepared by mixing Sn–Bi solder powder, flux, and epoxy system. The melting characteristics of the Sn–Bi solder alloy and the curing reaction of the epoxy system were measured by differential scanning calorimeter (DSC). A reflow profile was optimized based on the Sn–Bi reflow profile, and the Organic Solderability Preservative (OSP) Cu pad mounted 0603 chip resistor was chosen to reflow soldering and to prepare samples of the corresponding joint. The high temperature and humidity reliability of the solder joints at 85 #14;C/85% RH (Relative Humidity) for 1000 h and the thermal cycle reliability of the solder joints from
Technical Library | 2023-05-22 16:49:42.0
Our customers' issues • Apertures are getting smaller • Paste does not release as well • Contaminates the bottom of the stencil • Increases defects / reduces yield Insufficient solder Bridging Solder balls on surface of PCB Flux residue • Requires more frequent cleaning • Reduced efficiency (wasted time) • Increased use of consumables (cost) USC fabric (use "cheap" fabric to reduce cost) Lint creates more defects Cleaning chemistries (use IPA to reduce cost) IPA breaks down flux and can create more defects
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