Technical Library | 2013-01-24 19:16:35.0
The electronics industry has mainly adopted the higher melting point Sn3Ag0.5Cu solder alloys for lead-free reflow soldering applications. For applications where temperature sensitive components and boards are used this has created a need to develop low melting point lead-free alloy solder pastes. Tin-bismuth and tin-bismuth-silver containing alloys were used to address the temperature issue with development done on Sn58Bi, Sn57.6Bi0.4Ag, Sn57Bi1Ag lead-free solder alloy pastes. Investigations included paste printing studies, reflow and wetting analysis on different substrates and board surface finishes and head-in-pillow paste performance in addition to paste-in-hole reflow tests. Voiding was also investigated on tin-bismuth and tin-bismuth-silver versus Sn3Ag0.5Cu soldered QFN/MLF/BTC components. Mechanical bond strength testing was also done comparing Sn58Bi, Sn37Pb and Sn3Ag0.5Cu soldered components. The results of the work are reported.
Technical Library | 2016-03-24 17:37:09.0
Today's Electronic Industry is changing at a high pace. The root causes are manifold. So world population is growing up to eight billions and gives new challenges in terms of urbanization, mobility and connectivity. Consequently, there will raise up a lot of new business models for the electronic industry. Connectivity will take a large influence on our lives. Concepts like Industry 4.0, internet of things, M2M communication, smart homes or communication in or to cars are growing up. All these applications are based on the same demanding requirement – a high amount of data and increased data transfer rate. These arguments bring up large challenges to the Printed Circuit Board (PCB) design and manufacturing.This paper investigates the impact of different PCB manufacturing technologies and their relation to their high frequency behavior. In the course of the paper a brief overview of PCB manufacturing capabilities is be presented. Moreover, signal losses in terms of frequency, design, manufacturing processes, and substrate materials are investigated. The aim of this paper is, to develop a concept to use materials in combination with optimized PCB manufacturing processes, which allows a significant reduction of losses and increased signal quality.
Technical Library | 2017-04-20 13:51:14.0
The one constant in electronics manufacturing is change. Moore's Law, which successfully predicted a rate of change at which transistor counts doubled on Integrated Circuits (ICs) at lower cost for decades, is ceding to be an appropriate prediction tool. Increasing technical and economic requirements, deriving from the semiconductor environment, are cascaded down to the printed circuit and in particular to the IC substrate manufacturers. This is both a challenge and an opportunity for IC Substrate manufacturers, when dealing with the demands of the packaging market. (...)This paper introduces two new electroless copper baths developed for IC substrates manufacturing based on Semi Additive Process (SAP) technology (hereafter referred to as E'less Copper IC) and HDI production (hereafter referred to as E'less Copper HDI) and optimized for high throw into BMVs. An introduction to reliable throwing power measurement methods based on scanning electron microscope (SEM) is given, followed by a compilation and discussion of key performance criteria for each application, namely throwing power, copper adhesion on the substrate, dry film adhesion and reliability.
Technical Library | 2019-02-13 13:45:11.0
Development of information and telecommunications network is outstanding in recent years, and it is required for the related equipment such as communication base stations, servers and routers, to process huge amount of data in no time. As an electrical signal becomes faster and faster, how to prevent signal delay by transmission loss is a big issue for Printed Circuit Boards (PCB) loaded on such equipments. There are two main factors as the cause of transmission loss; dielectric loss and conductor loss. To decrease the dielectric loss, materials having low dielectric constant and low loss tangent have been developed. On the other hand, reducing the surface roughness of the copper foil itself to be used or minimizing the surface roughness by modifying surface treatment process of the conductor patterns before lamination is considered to be effective in order to decrease the conductor loss. However, there is a possibility that reduction in the surface roughness of the conductor patterns will lead to the decrease in adhesion of conductor patterns to dielectric resin and result in the deterioration of reliability of PCB itself. In this paper, we will show the evaluation results of adhesion performance and electrical properties using certain type of dielectric material for high frequency PCB, several types of copper foil and several surface treatment processes of the conductor patterns. Moreover, we will indicate a technique from the aspect of surface treatment process in order to ensure reliability and, at the same time, to prevent signal delay at the signal frequency over 20 GHz.
Technical Library | 2020-05-07 03:46:27.0
The selective soldering process has evolved to become a standard production process within the electronics assembly industry, and now accommodates a wide variety of through-hole component formats in numerous applications. Most through-hole components can be easily soldered with the selective soldering process without difficulty, however some types of challenging components require additional attention to ensure optimum quality control is maintained. Several high thermal mass components can place demands on the selective soldering process, while the use of specialized solder fixtures and/or pallets often places an additional thermal demand on the preheating process. Fine-pitch through-hole components and connectors place a different set of demands on the selective soldering process and typically require special attention to lead projection and traverse speed to minimize bridging between adjacent pins. Dual in-line memory module (DIMM) connectors, compact peripheral component interface (cPCI) connectors, coax connectors and other high thermal mass components as well as fine-pitch microconnectors,can present challenges when soldered into backplanes or multilayer printed circuit board assemblies. Adding to this challenge, compact peripheral component interface connectors can present additional solderability issues due to their beryllium copper termination pins.
Technical Library | 2021-06-15 18:36:00.0
To compensate for the insufficiency and instability of solder paste dispensing and printing that are used in the SMT (Surface Mount Technology) production process, a noncontact solder paste jetting system driven by a piezoelectric stack based on the principle of the nozzle-needle-system is introduced in this paper, in which a miniscule gap exists between the nozzle and needle during the jetting process. Here, the critical jet ejection velocity is discussed through theoretical analysis. The relations between ejection velocity and needle structure, needle velocity, and nozzle diameter were obtained by FLUENT software. Then, the prototype of the solder paste jetting system was fabricated, and the performance was verified by experiments. The effects of the gap between nozzle and needle, the driving voltage, and the nozzle diameter on the jetting performance and droplet diameter were obtained. Solder paste droplets 0.85 mm in diameter were produced when the gap between the nozzle and needle was adjusted to 10 _m, the driving voltage to 80 V, the nozzle diameter to 0.1 mm, and the variation of the droplet diameter was within _3%.
Technical Library | 2013-08-22 14:28:58.0
Tin-rich solders are widely applied in the electronic industry in the majority of modern printed circuit boards (PCBs). Because the use of lead-tin solders has been banned in the European Union since 2006, the problem of the bridging of adjacent conductors due to tin whisker growth (limited before by the addition of Pb) has been reborn. In this study tin alloys soldered on glass-epoxy laminate (typically used for PCBs) are considered. Scanning ion microscopy with Focused Ion Beam (FIB) system and energy-dispersive X-ray spectroscopy (EDXS) were used to determine correlations between spatial non-uniformities of the glass-epoxy laminate, the distribution of intermetallic compounds and whisker growth.
Technical Library | 2023-07-16 21:56:12.0
Imagine being able to accurately predict the correct artwork compensations prior to taking on a large quick turn order regardless of the board design, materials, or process. Such predictive power is possible and can be achieved without a lot of cost and complexity. This paper shows how small sets of designed experiments can be used to create a cImagine being able to accurately predict the correct artwork compensations prior to taking on a large quick turn order regardless of the board design, materials, or process. Such predictive power is possible and can be achieved without a lot of cost and complexity. This paper shows how small sets of designed experiments can be used to create a compensation model. Before a discussion of the design of experiments (DOEs), we will examine key processes and material variables that affect movement as demonstrated on real board design layout in a real production process. Only the few most relevant variables need to be included in the experimental design. A solution is presented that uses small experiments that provide the required information for constructing a general compensation model.mpensation model. Before a discussion of the design of experiments (DOEs), we will examine key processes and material variables that affect movement as demonstrated on real board design layout in a real production process. Only the few most relevant variables need to be included in the experimental design. A solution is presented that uses small experiments that provide the required information for constructing a general compensation model.
Technical Library | 2021-10-20 18:21:06.0
The solderability of the SAC305 alloy in contact with printed circuit boards (PCB) having different surface finishes was examined using the wetting balance method. The study was performed at a temperature of 260 _C on three types of PCBs covered with (1) hot air solder leveling (HASL LF), (2) electroless nickel immersion gold (ENIG), and (3) organic surface protectant (OSP), organic finish, all on Cu substrates and two types of fluxes (EF2202 and RF800). The results showed that the PCB substrate surface finish has a strong effect on the value of both the wetting time t0 and the contact angle h. The shortest wetting time was noted for the OSP finish (t0 = 0.6 s with EF2202 flux and t0 = 0.98 s with RF800 flux), while the ENIG finish showed the longest wetting time (t0 = 1.36 s with EF2202 flux and t0 = 1.55 s with RF800 flux). The h values calculated from the wetting balance tests were as follows: the lowest h of 45_ was formed on HASL LF (EF2202 flux), the highest h of 63_ was noted on the OSP finish, while on the ENIG finish, it was 58_ (EF2202 flux). After the solderability tests, the interface characterization of cross-sectional samples was performed by means of scanning electron microscopy coupled with energy dispersive spectroscopy.
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.
