Technical Library | 2012-10-18 21:58:51.0
First published in the 2012 IPC APEX EXPO technical conference proceedings. In this paper, we report on a comprehensive study regarding the morphology evolution and voiding of SnAgCu solder joints on the central pad of two different packages – QFN and an Agilent package called TOPS – on PCBs with a Ni/Au surface finish.
Technical Library | 2013-08-08 15:23:11.0
In this project Machine Vision PCB Inspection System is applied at the first step of manufacturing, i.e., the making of bare PCB. We first compare a PCB standard image with a PCB image, using a simple subtraction algorithm that can highlight the main problem-regions. We have also seen the effect of noise in a PCB image that at what level this method is suitable to detect the faulty image. Our focus is to detect defects on printed circuit boards & to see the effect of noise. Typical defects that can be detected are over etchings (opens), under-etchings (shorts), holes etc...
Technical Library | 2008-07-01 18:59:09.0
As lead-free and RoHS compliancy fast approaches, it is more important than ever to build it right the first time. Lead-free assembly and RoHS will bring about numerous changes and the number of variables with which to contend is increasing, creating increased risk of defects and reduced product reliability. However, understanding what the variables are and their impact on the assembly can great increase product reliability.
Technical Library | 2020-07-15 18:29:34.0
In the early 2000s the first fine-pitch ball grid array devices became popular with designers looking to pack as much horsepower into as small a space as possible. "Smaller is better" became the rule and with that the mechanical drilling world became severely impacted by available drill bit sizes, aspect ratios, and plating methodologies. First of all, the diameter of the drill needed to be in the 0.006" or smaller range due to the reduction of pad size and spacing pitch. Secondly, the aspect ratio (depth to diameter) became limited by drill flute length, positional accuracy, rigidity of the tools (to prevent breakage), and the throwing power of acid copper plating systems. And lastly, the plating needed to close up the hole as much as possible, which led to problems with voiding, incomplete fill, and gas/solution entrapment.
Technical Library | 2021-12-16 01:52:32.0
Package on Packages (PoP) find use in applications that require high performance with increased memory density. One of the greatest benefits of PoP technology is the elimination of the expensive and challenging task of routing high-speed memory lines from under the processor chip out to memory chip in separate packages. Instead, the memory sits on top of the processor and the connections are automatically made during assembly. For this reason PoP technology has gained wide acceptance in cell phones and other mobile applications. PoP technology can be assembled using one-pass and two-pass assembly processes. In the one-pass technique the processor is first mounted to the board, the memory is mounted to the processor and the finished board is then run through the reflow oven in a single pass. The two-pass technique has an intermediate step in which the memory is first mounted onto the processor.
Technical Library | 2014-07-02 16:46:09.0
Growth behaviors of intermetallic compounds (IMCs) and Kirkendall voids in Cu/Sn/Cu microbump were systematically investigated by an in-situ scanning electron microscope observation. Cu–Sn IMC total thickness increased linearly with the square root of the annealing time for 600 h at 150°C, which could be separated as first and second IMC growth steps. Our results showed that the growth behavior of the first void matched the growth behavior of second Cu6Sn5, and that the growth behavior of the second void matched that of the second Cu3Sn. It could be confirmed that double-layer Kirkendall voids growth kinetics were closely related to the Cu–Sn IMC growth mechanism in the Cu/Sn/Cu microbump, which could seriously deteriorate the mechanical and electrical reliabilities of the fine-pitch microbump systems
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 | 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 11:28:39.0
There are many things that can go wrong when soldering to gold plate over nickel surfaces. First of all, we know that gold and solder are not good friends, as any time solder comes into contact with gold, something seems to go wrong. Either the solder bonds to the gold and eventually pulls off as the tin and gold cross-migrate, leaving voids; or the solder completely removes the gold and is expected to bond to the metal which was under the gold.
Technical Library | 2007-04-04 11:43:41.0
The present work offers a discussion and a first case study to identify and illustrate voiding mechanisms for a particular TIM between a heat spreader and the back of a flip chip. Pronounced differences were observed between stencil printing and dispensing in terms of initial void formation, apparently related to the specific properties of the material. Measurements of the effects of heat ramp rate and peak temperature showed the subsequent evolution and final void size distribution to be determined by the initial part of the cure profile up to the material gelling temperature.
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