Technical Library | 2019-10-16 23:18:15.0
Despite being a continuous subject of discussion, the existence of voids and their effect on solder joint reliability has always been controversial. In this work we revisit previous works on the various types of voids, their origins and their effect on thermo-mechanical properties of solder joints. We focus on macro voids, intermetallics micro voids, and shrinkage voids, which result from solder paste and alloy characteristics. We compare results from the literature to our own experimental data, and use fatigue-crack initiation and propagation theory to support our findings. Through a series of examples, we show that size and location of macro voids are not the primary factor affecting solder joint mechanical and thermal fatigue life. Indeed, we observe that when these voids area conforms to the IPC-A-610 (D or F) or IPC-7095A standards, macro voids do not have any significant effect on thermal cycling or drop shock performance.
Technical Library | 1999-05-06 13:35:26.0
The invention of the transistor almost fifty years ago was one of the most important technical developments of this century. It has had profound impact on the way we live and the way we work. This paper describes the events that led to the invention of the point-contact transistor in December of 1947. It continues with the development of the theory of the junction transistor in early 1948 and the fabrication of the first grown-junction transistor in 1950.
Technical Library | 2001-05-23 16:23:26.0
Lowering inventories is one of the quickest ways to decrease working capital needs. Performance measurements, such as the old standby ROA (return on assets) and the newer EVA (economic value added), as well as other measures that gauge how efficiently capital is used, have become more common organizational drivers. In fact, many an executive’s bonus depends, at least in part, on how efficiently capital is used.
Technical Library | 2017-04-13 10:57:53.0
Parylene has been used for decades as a barrier layer to protect critical devices and components. The parylene deposition process typically requires an adhesion promotion step to make sure the parylene adheres well to the base substrate. Typical adhesion methods don't work well on Kapton and Polyamide, until VSI Parylene came up with a solution.
Technical Library | 2018-10-29 05:03:59.0
We found that NPI process of SMT is mostly similar and sometimes overlapping to tooling process. In addition, in most cases the programmer is part of the team working on the NPI process. So, QPlan was extended with NPI Tools as a part of tooling process. This allows the team to carry out the NPI process at offline. And at the end of it, they can create corrected SMT program at zero time.
Technical Library | 2019-08-07 22:56:45.0
The requirement to reconsider traditional soldering methods is becoming more relevant as the demand for bottom terminated components (QFN/BTC) increases. Thermal pads under said components are designed to enhance the thermal and electrical performance of the component and ultimately allow the component to run more efficiently. Additionally, low voiding is important in decreasing the current path of the circuit to maximize high speed and RF performances. The demand to develop smaller, more reliable, packages has seen voiding requirements decrease below 15 percent and in some instances, below 10 percent.Earlier work has demonstrated the use of micro-fluxed solder preforms as a mechanism to reduce voiding. The current work builds upon these results to focus on developing an engineered approach to void reduction in leadless components (QFN) through increasing understanding of how processing parameters and a use of custom designed micro-fluxed preforms interact. Leveraging the use of a micro-fluxed solder preform in conjunction with low voiding solder paste, stencil design, and application knowhow are critical factors in determining voiding in QFN packages. The study presented seeks to understand the vectors that can contribute to voiding such as PCB pad finish, reflow profile, reflow atmosphere, via configuration, and ultimately solder design.A collaboration between three companies consisting of solder materials supplier, a power semiconductor supplier, and an electronic assembly manufacturer worked together for an in-depth study into the effectiveness of solder preforms at reducing voiding under some of the most prevalent bottom terminated components packages. The effects of factors such as thermal pad size, finish on PCB, preform types, stencil design, reflow profile and atmosphere, have been evaluated using lead-free SAC305 low voiding solder paste and micro-fluxed preforms. Design and manufacturing rules developed from this work will be discussed.
Technical Library | 1999-05-06 13:38:45.0
This paper traces the key steps that led to the invention of the integrated circuit (IC). The first part of this paper reviews the steady improvements in the performance and fabrication of single transistors in the decade after the Bell Labs breakthrough work in 1947. It sketches the various developments needed to produce a practical IC. In addition, the more advanced processes such as diffusion, oxide masking, photolithography, and epitaxy, which culminated in the planar process, are summarized.
Technical Library | 1999-05-07 10:23:43.0
Software decoding of Dolby Digital allows it to become a baseline capability on the PC, with greater flexibility than a hardware approach. Intel's MMX™ technology provides instructions that can significantly speed up the execution of the Dolby Digital decoder, freeing up the processor to perform other tasks such as video decoding and/or audio enhancement. Intel has worked closely with Dolby Laboratories to define an implementation of Dolby Digital based on MMX technology that has achieved Dolby's certification of quality.
Technical Library | 1999-07-20 11:00:12.0
It's quite common for a power supply (PSU) designer to work with a circuit designer to realize a system design compliant with international EMC regulations. PSU designers will be well aware of the requirement of the power supply to provide clean DC voltage and not disturb the AC mains voltage. However, they may not have any idea of the noise that can potentially be introduced to the mains through the PSU by the target circuit. Likewise, the circuit designers (digital or analogue) may not know what attenuation the PSU will provide.
Technical Library | 1999-08-09 11:09:42.0
Organic Solderability Preservatives (OSPs), also known as anti-tarnish, on bare copper printed circuit boards (PCBs) are becoming more prevalent in the electronics industry as the low-cost replacement to Hot Air Solder Leveling (HASL). Introducing the anti-tarnish alternative into the customer sites requires working closely with the coating supplier, assembler, and Original Equipment Manufacturer (OEM) to gain a mutual understanding of respective processing concerns and finished product requirements.
