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Long-Term Non-Operating Reliability of Selected Electronic Products
Published in Judy Pecht, Michael Pecht, Long-Term Non-Operating Reliability of Electronic Products, 2019
Requirements and test methods for solderability are specified in J-STD-003, ”Solderability Test for Printed Boards,” which contains four tests with established accept/reject criteria: the edge dip test, the rotary dip test, the solder flow test, and the wave solder test. In addition, it contains a wetting balance test which currently does not have established accept/reject criteria.
Introduction
Published in Michael Pecht, Handbook of Electronic Package Design, 2018
Michael D. Osterman, Michael Pecht
The solderability of the metallized conductor pads and other metal materials used in electronic packaging is an important manufacturing issue. The ability of a metal surface to accept a solder bond (wet) is critical to the formation of proper electrical and mechanical joints in the electronic assembly. Solderability is affected by the solder type, flux, and soldered material. In addition, the material must be compliant with the machining and chemical processes to which it will be exposed in the creation of the final electronic product.
Developing Measurement for Experimentation
Published in Donald B. Owen, Subir Ghosh, William R. Schucany, William B. Smith, Statistics of Quality, 2020
An example in which the size of the measurement range is an issue is the measurement of solderability with a wetting balance (Lin and Friend, 1989). The solderability of a lead from an electronic component is a property determined by the way molten solder wets the surface of the lead. Solderability is measured with a wetting balance, which produces a curve of force versus time. This curve has four parts. First, the curve proceeds downward from 0 force as the lead is pushed into a solder bath. Second, the curve reverses and starts upward as the lead wets. This upward movement may level off as the solder rises up the lead to some height. Third, starting at a specified time from initiation, the curve moves upward again as the lead is pulled from the bath. Fourth, the curve returns downward to 0 force as the lead is freed from the bath. Generally, a lead with better solderability produces a curve that is higher at each point in time. Various features of the wetting force curve have been proposed as a measurement system response. The issue is that the units of interest determine the right choice of feature. For example, a feature useful for a group of tinned leads is the time from initiation to the point in the second part at which the curve crosses 0. However, this feature may not have the range needed for comparison of a group that includes oxidized bare copper leads because the curve may never cross 0 until the third part. Another feature must be chosen for such a group. In a sense, the entire wetting force curve has a greater measurement range than any of the individual features usually considered. Nair and Pregibon (1993) highlight the general problem of loss of information in the reduction of a function response to a univariate response.
Novel silver-enhanced hard gold electrodeposit applied for electrical contacts: comparison with conventional gold–cobalt alloy
Published in Transactions of the IMF, 2022
Yen Ngoc Nguyen, Jongmin Lee, Injoon Son
Solderability refers to the capacity of molten solder to spread over the coating surface during the soldering process, whereby a metallurgical bond is formed between solder and substrate that connects the two following solidification. Poor solderability may result in defects in the solder joints, including micro-cracks or voids, which increase the contact resistance. The solderability of Au coatings can be characterised by the solder spreadability and wettability with a Sn-based alloy solder. The evaluated solder spreadability is presented in Figure 2. The solder spreadability in conjunction with the Au–Ag coating was higher than that of the Au–Co coating as the aging duration was increased. As the aging duration was extended, the Au–Co coating presented a markedly decreased solder spreadability. Conversely, the Au–Ag coating maintained a stable solder spreadability at aging times of up to 360 s before decreasing mildly over 600 s of aging. Additionally, the solder ball completely spread over the Au–Ag coating, resulting in small contact angles (Figure 3). The Au–Ag coating exhibited a significantly smaller contact angle with the solder compared to that of the Au–Co coating, indicating an increased wettability of Au–Ag coating. In addition, based on standard deviations, variations in solder spreadability and contact angles induced by Au–Co coating over measurements at 10 time intervals were larger than those associated with Au–Ag coating, indicating the poorer reliability of Au–Co relative to Au–Ag coating.
Electrodeposition of Pd–Ag alloy for electrical contacts
Published in Surface Engineering, 2022
Yen Ngoc Nguyen, Jisun Yoon, Jiyeon Shin, Injoon Son
In addition to contact resistance, solderability of coatings is a crucial property as poor solderability might result in defect sites in the solder joint, intensifying the resistance. Figure 8 shows the contact angles of Pd-based coatings with the solder ball after heating at 260°C for 30 s. The Pd-based coatings presented a decrease in the contact angles with the solder ball with an increase in the Ag content, demonstrating that the wettability of the Pd-based coatings with solder was improved when the Ag content was increased. This was elucidated that Ag could diffuse into Sn with a fast diffusion rate, which is only inferior to Au [33]. As a result, the solder spreadability obtained using Pd-based coatings increased with an increase in the atomic per cent of Ag (Figure 9).
Sn-Cu intermetallic compound laminated film with excellent friction coefficient, contact resistance, and solder wettability
Published in Transactions of the IMF, 2022
Hiroki Hayashi, Naohiro Takaine, Hiroyuki Funasaki, Mitsuhiro Watanabe
A solderability tester (SAT-5200 manufactured by Rhesca Co., Ltd.) was used. Evaluation was performed by the wetting balance method, and the solder temperature was 245 ± 3 °C, the immersion depth was 3 mm, the immersion time was 10 s, and the immersion speed was 5 mm s−1. Sn-3.0Ag-0.5Cu (M705 manufactured by Senju Metal Industry Co., Ltd.) was used as the solder, and a rosin-based flux (NA-200 manufactured by Tamura Corporation) was used. In addition, as a reliability evaluation, the authors also confirmed the solder wettability when the product was held at 160 °C for 120 h. Furthermore, in order to confirm the relationship between the Sn plating thickness of the surface layer and the solder wettability in the Sn-Cu alloy laminated plating, a sample in which the Sn plating thickness in the Sn-Cu alloy laminated plating was changed to 0.1–0.5 µm was prepared and evaluated.