Technical Library | 2007-01-03 16:36:58.0
Solder paste dispensing is not a new process. However, today's microelectronics present a daunting array of technical challenges to meet deposit size requirements. The need for better paste formulations, more precise equipment, and more tightly controlled processes is driving paste suppliers and equipment suppliers to develop new methods and materials. The most challenging solder paste deposits are those smaller than 0.25mm in diameter and today’s electronics demand such deposits. This paper addresses the process requirements for solder paste micro-deposits in terms of material, equipment and process variable control required for success in producing 0.25mm and smaller deposits.
Technical Library | 2018-11-06 12:42:25.0
Solder paste is a homogeneous, stable suspension of solder powder particles suspended in a flux binder, and is one of the most important process materials today in surface mount technology (SMT). By varying the solder particle size, distribution and shape, as well as the other constituent materials, the rheology and printing performance of solder pastes can be controlled. Paste flow behavior is very important in defining the printing performance of any paste.The purpose of this paper is to study the rheological behavior of SAC (Sn-Ag-Cu) solder paste used for surface mount applications in the electronic industry. The reason why the rheological tests are presented in this paper are two critical sub-processes: aperture filling and paste withdraw. In this paper, we report on the investigation of the rheological profiles, the serrated cone-to-plate system was found as effective in parameter minimizing the wall-slip effect
Technical Library | 2010-05-12 16:21:05.0
Numerous studies have shown that greater than 60% of end of line defects in SMT assembly can be traced to solder paste and the printing process. Reflowing adds another 15% or so. In light of this fact, it is surprising that no simplified procedure for solder paste evaluation has been documented. This paper is about such a procedure.
Technical Library | 2017-12-27 22:52:43.0
To compensate for the insufficiency and instability of solder paste dispensing and printing that are used in the SMT 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.
Technical Library | 2021-05-13 16:09:02.0
The 2017 iNEMI Board and Assembly Roadmap forecasts that, due to economic, environmental and technical drivers, use of low temperature solder pastes will increase significantly and reach 10% of all solder paste used for board assembly by 2021.
Technical Library | 2007-01-31 12:08:36.0
Air-powered dispensing systems use controlled pulses of air pressure to dispense solder paste from syringe reservoirs in uniform amounts. In this paper, EFD explains the most critical variables affecting air-powered dispensing of solder pastes and shows how to manage those variables to your advantage.
Technical Library | 2016-09-01 16:21:11.0
Sn3.0Ag0.5Cu (SAC305) is currently the most popular near eutectic lead-free alloy used in the manufacturing processes. Over the last several years, the price of silver has dramatically increased driving a desire for lower silver alloy alternatives. As a result, there is a significant increase in the number of alternative low/no silver lead-free solder alloys available in the industry recently. Our previous study showed that many alternative low silver solder paste materials had good printing and wetting performance as compared to SAC305 solder pastes. However, there is lack of information on the reliability of alternative alloy solder joints assembled using alternative low silver alloy solder pastes.In this paper, we will present the reliability study of lead-free solder joints reflowed using various lead-free alloy solder pastes after thermal cycling test (3000 cycles, 0°C to 100°C). Six different lead-free pastes were investigated. SAC305 solder joints were used as the control. Low and no silver solder pastes and a low temperature SnBiAg solder pastes were also included.
Technical Library | 2015-10-01 16:12:51.0
Solder paste printing is known to be one of the most difficult processes to quality assure in electronic manufacturing. The challenge increases as the technology development moves toward a mix between large modules and small chip components on large and densely populated printed circuit boards. Having a process for quality assurance of the solder paste print is fast becoming a necessity.This article describes a method to ensure quality secured data from both solder paste printers and inspection machines in electronic assembly manufacturing. This information should be used as feedback in order to improve the solder paste printing process.
Technical Library | 2007-01-31 14:10:17.0
This white paper is suitable for both new and experienced users. It is a practical education in the use and misuse of auger valves for solder paste dispensing.
Technical Library | 2017-11-15 22:49:14.0
While a significant level of voiding can be tolerated in solder joints where electrical conductivity is the main requirement, voiding at any level severely compromises thermal conductivity. For example, in LED lighting modules effective conduction of heat through the 1st level die attach to the substrate and then through the 2nd level attach to the heat sink is critical to performance so that voiding in the solder joints at both levels must be minimized. (...) In this paper, the authors will review the factors that influence the incidence of voids in small and large area solder joints that simulate, respectively, the 1st and 2nd level joints in LED modules and discuss mitigation strategies appropriate to each level. They will also report the results of a study on the effect on the incidence of voids of flux medium formulation and the optimization of the thermal profile to ensure that most of the volatiles are released early in the reflow process.
