Technical Library | 2019-05-29 23:10:30.0
There are times when a PCB prototype needs to be built quickly to test out a design. In such cases where it is known early on that there will be multiple iterations or that a "one and done" assembly will be made that there will be some SMT assemblers who choose to hand print solder paste onto the board using a "frameless" stencil. In such cases where hand printing is used, the consistency of the printing technique has typically been in question. Furthermore, the effectiveness of both the nanocoatings as well as the higher end stainless steel materials, which have been heretofore studied in controlled printing environments, will be evaluated for their impact on the hand printing process.The purpose of the study was to determine the effectiveness of select nanocoating materials as well as certain high end stainless steel stencil materials as they relate to the manual SMT printing process. A variety of nanocoatings were applied to SMT metal stencils and solder paste volume measurements were taken to compare the effectiveness.
Technical Library | 2016-08-24 06:15:35.0
From consumer electronics to systems control, automotive technology to aviation and aerospace – today, electronics are absolutely essential in many sectors. They increasingly replace mechanical components, eliminating wear and tear and thereby extending the service life. What is easily forgotten in this regard is that electronics are also subject to the laws of mechanics. Mechanical test equipment is crucial to test components for the secure hold of welded, soldered or adhesive bonds. A new, mechanically intricate test probe with universal clamping jaws, that can even grasp the individual bonding wires, is in line with the trend toward ever smaller components. Serving as an actuator for these is a micro drive that can be precisely controlled using a miniaturised motion controller to relieve the control unit in the test device.
Technical Library | 2018-11-07 03:31:04.0
Generally speaking, there are not many cases of insufficient solder and solder short in BGA soldering, but it is not impossible. Here we discuss some elements may cause it
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 | 2022-07-11 09:24:48.0
The change of squeegee pressure has a significant impact on printing. Too small pressure will make the solder paste unable to effectively reach the bottom of the stencil opening and not be well deposited on the pad. Too much pressure will cause tin The paste is printed too thin and can even damage the stencil.
Technical Library | 2021-09-08 13:43:56.0
Manganese can be an optimal alloying addition in lead-free SAC (SnAgCu) solder alloys because of its low price and harmless nature. In this research, the mechanical properties of the novel SAC0307 (Sn/Ag0.3/Cu0.7) alloyed with 0.7 wt.% Mn (designated as SAC0307-Mn07) and those of the traditionally used SAC305 (Sn96.5/Ag3/Cu0.5) solder alloys were investigated by analyzing the shear force and Vickers hardness of reflowed solder balls. During the preparation of the reflowed solder balls, different cooling rates were used in the range from 2.7 K/s to 14.7 K/s.
Technical Library | 2014-06-19 18:13:23.0
For high-density electronic packaging,the application of flip-chip solder joints has been well received in the microelectronics industry. High-lead(Pb) solders such as Sn5Pb95 are presently granted immunity from the RoHS requirements for their use in high-end flip-chip devices, especially in military applications. In flip-chip technology for consumer electronic products, organic substrates have replaced ceramic substrates due to the demand for less weight and low cost. However, the liquidus temperatures of high-Pb solders are over 300°C which would damage organic substrates during reflow because of the low glass transition temperature. To overcome this difficulty, the composite solder approach was developed...
Technical Library | 2021-09-08 13:57:37.0
While the presence of silver in SAC solder provided excellent temperature cycling durability, the silver in high silver SAC alloy also made the solders susceptible to failures under drop/shock loading. To improve the drop/shock reliability, the silver content in SAC alloys was reduced from three percent, to as low as no silver. Solder dopants, also known as microalloy additions, are elements (typically 0.1% or lower) other than the main constituents of the alloy that have been shown to improve solder performance. Commonly used microalloy additions include nickel (Ni), bismuth (Bi), manganese (Mn), and antimony (Sb).
Technical Library | 2019-11-07 08:59:14.0
Inductors realized with high permeable MnZn ferrite require, unlike iron-powder cores with an inherent dis-tributed gap, a discrete air gap in the magnetic circuit to prevent saturation of the core material and/or tune the inductance value. This large discrete gap can be divided into several partial gaps in order to reduce the air gap stray field and consequently the proximity losses in the winding. The multi-gap core, realized by stacking several thin ferrite plates and inserting a non-magnetic spacer material between the plates, however, exhibits a substan-tial increase in core losses which cannot be explained from the intrinsic properties of the ferrite. In this paper, a comprehensive overview of the scientific literature regarding machining induced core losses in ferrite, dating back to the early 1970s, is provided which suggests that the observed excess core losses could be attributed to a deterioration of ferrite properties in the surface layer of the plates caused by mechanical stress exerted during machining.
Technical Library | 2004-09-02 11:56:32.0
The main goal of this paper is to highlight the importance of interrelating the physics and the chemistry in wave soldering and soft soldering in general. Often we find the disciplines of chemistry and physics being analyzed distinct and separate. However in the quest for alternative ways for leading edge competitive and especially environmental friendly manufacturing, separating or ignoring this interrelationship is detrimental to the success of No-Residue soldering.
