A Joining Technique Using Multilayer Lead-Indium-Gold Composite Deposited In High Vacuum

1993 ◽  
Vol 314 ◽  
Author(s):  
Chin C. Lee ◽  
Chen-Yu Wang ◽  
Yi-Chia Chen ◽  
Goran Matijasevic
Keyword(s):  
Composite Solder ◽  
Electronic Devices ◽  
High Vacuum ◽  
Solution Phase ◽  
Solid Solution Phase ◽  
Shear Tests ◽  
Acoustic Microscope ◽  
Scavenging Effect ◽  
Die Attach ◽  
Scanning Acoustic Microscope

AbstractA joining technique for electronic devices has been developed. This technique uses a leadindium- gold multilayer composite solder deposited directly on GaAs wafers in high vacuum to prevent indium oxidation. The gold layer on the composite further protects the indium layer from oxidation in atmosphere. The GaAs dies are bonded to a gold-coated alumina substrate at a process temperature of 250°C. Nearly perfect joints are achieved as verified by a scanning acoustic microscope (SAM). SEM and EDX results indicate that the alloy joint consists of AuIn2 grains embedded in an In-Pb solid solution phase, as predicted from the Au- In-Pb phase diagram. Compared to lead-tin solder, indium-lead solder has been shown by others to exhibit much better fatigue resistance and have much less of a scavenging effect. Thermal shock as well as shear tests confirm that a good die attach is obtained with the leadindium- gold composite.

Indium-Copper Multilayer Composite Solder for Fluxless Bonding

1995 ◽  
Vol 390 ◽  
Author(s):  
Chin C. Lee ◽  
Yi-Chia Chen
Keyword(s):  
Composite Solder ◽  
Alloy Composition ◽  
High Vacuum ◽  
Bonding Process ◽  
Microscope Examination ◽  
Specific Design ◽  
Acoustic Microscope ◽  
Fluxless Bonding ◽  
Pure Indium ◽  
Scanning Acoustic Microscope

ABSTRACTA 200°C fluxless process is developed to produce In-Cu joints. The fluxless feature is achieved by the prevention of indium oxidation during the solder fabrication and the bonding process. Indium and copper are deposited on an object in high vacuum to inhibit indium oxidation. Copper interacts with indium to form CuIn compound that further protects the inner indium from oxidation. For a specific design, the resulting joints consist of mainly CuIn intermetallic grains surrounded by a small amount of pure indium as revealed by SEM with EDX. Scanning acoustic microscope examination indicates that the joints are nearly void-free. This technology enables versatile control of the alloy composition, thus leading to several remelting temperatures and various physical properties.

Transition alpha structure in beta-isomorphous Nb-Hf alloys

1987 ◽  
Vol 45 ◽  
pp. 232-233
Author(s):  
R.W. Carpenter ◽  
Changhai Li ◽  
David J. Smith
Keyword(s):  
Solid Solution ◽  
Solution Phase ◽  
Miscibility Gap ◽  
Large Strains ◽  
Solid Solution Phase ◽  
Two Phase ◽  
Diffuse Intensity ◽  
Metastable Form ◽  
The Matrix ◽  
Equilibrium Morphology

Binary Nb-Hf alloys exhibit a wide bcc solid solution phase field at temperatures above the Hfα→ß transition (2023K) and a two phase bcc+hcp field at lower temperatures. The β solvus exhibits a small slope above about 1500K, suggesting the possible existence of a miscibility gap. An earlier investigation showed that two morphological forms of precipitate occur during the bcc→hcp transformation. The equilibrium morphology is rod-type with axes along <113> bcc. The crystallographic habit of the rod precipitate follows the Burgers relations: {110}||{0001}, <112> || <1010>. The earlier metastable form, transition α, occurs as thin discs with {100} habit. The {100} discs induce large strains in the matrix. Selected area diffraction examination of regions ∼2 microns in diameter containing many disc precipitates showed that, a diffuse intensity distribution whose symmetry resembled the distribution of equilibrium α Bragg spots was associated with the disc precipitate.

Signature Analysis of Package Delamination Using Scanning Acoustic Microscope

1996 ◽  
Author(s):  
S.X. Li ◽  
K. Lee ◽  
J. Hulog ◽  
R. Gannamani ◽  
S. Yin
Keyword(s):  
Failure Analysis ◽  
Early Stage ◽  
Signature Analysis ◽  
Acoustic Microscope ◽  
Reflow Soldering ◽  
Moisture Expansion ◽  
Scanning Acoustic Microscope ◽  
Package Reliability

Abstract Package delaminations are often associated with electrical and package reliability problems in IC devices. Delaminations caused by electrical-over-stress (EOS) and moisture expansion during reflow soldering have shown different delamination patterns. A Scanning Acoustic Microscope (SAM) can be used to detect package delaminations. Understanding these delamination signatures can help us quickly identify the failure cause at an early stage of the failure analysis.

Failure Analysis of Flip-Chip Interconnections Through Acoustic Microscopy

1996 ◽  
Author(s):  
O. Diaz de Leon ◽  
M. Nassirian ◽  
C. Todd ◽  
R. Chowdhury
Keyword(s):  
Failure Analysis ◽  
Large Scale ◽  
Flip Chip ◽  
Ultrasonic Waves ◽  
Acoustic Microscopy ◽  
Acoustic Microscope ◽  
Chip Technology ◽  
Ball Joints ◽  
Non Destructive ◽  
Scanning Acoustic Microscope

Abstract Integration of circuits on semiconductor devices with resulting increase in pin counts is driving the need for improvements in packaging for functionality and reliability. One solution to this demand is the Flip- Chip concept in Ultra Large Scale Integration (ULSI) applications [1]. The flip-chip technology is based on the direct attach principle of die to substrate interconnection.. The absence of bondwires clearly enables packages to become more slim and compact, and also provides higher pin counts and higher-speeds [2]. However, due to its construction, with inherent hidden structures the Flip-Chip technology presents a challenge for non-destructive Failure Analysis (F/A). The scanning acoustic microscope (SAM) has recently emerged as a valuable evaluation tool for this purpose [3]. C-mode scanning acoustic microscope (C-SAM), has the ability to demonstrate non-destructive package analysis while imaging the internal features of this package. Ultrasonic waves are very sensitive, particularly when they encounter density variations at surfaces, e.g. variations such as voids or delaminations similar to air gaps. These two anomalies are common to flip-chips. The primary issue with this package technology is the non-uniformity of the die attach through solder ball joints and epoxy underfill. The ball joints also present defects as open contacts, voids or cracks. In our acoustic microscopy study packages with known defects are considered. It includes C-SCAN analysis giving top views at a particular package interface and a B-SCAN analysis that provides cross-sectional views at a desired point of interest. The cross-section analysis capability gives confidence to the failure analyst in obtaining information from a failing area without physically sectioning the sample and destroying its electrical integrity. Our results presented here prove that appropriate selection of acoustic scanning modes and frequency parameters leads to good reliable correlation between the physical defects in the devices and the information given by the acoustic microscope.

Stacked Die Analysis Using C-mode Scanning Acoustic Microscope

2005 ◽  
Author(s):  
Li Na ◽  
Jawed Khan ◽  
Lonnie Adams
Keyword(s):  
Data Acquisition ◽  
Image Interpretation ◽  
Acoustic Microscopy ◽  
Scanning Acoustic Microscopy ◽  
Acoustic Microscope ◽  
Analysis Mode ◽  
Scanning Acoustic Microscope

Abstract For stacked die package delamination inspection using C-mode acoustic microscope, traditional interface and thorough scan techniques cannot give enough of information when the delamination occurs in multi-interfaces, and echoes from adjacent interfaces are not sufficiently separated from each other. A thinner thickness in the stacked-die package could complicate C-mode scanning acoustic microscopy (CSAM) analysis and sometimes may lead to false interpretations. The first objective of this paper is to briefly explain the CSAM mechanism. Based on that, some of the drawbacks of current settings in detecting the delamination for stacked-die packages are presented. The last objective is to introduce quantitative B-scan analysis mode (Q-BAM) and Zip-Slice technologies in order to better understand and improve the reliability of detecting the delamination in stacked-die packages. Therefore, a large portion of this paper focuses on the Q-BAM and Zip-Slice data acquisition and image interpretation.

Non-equilibrium Ti-Fe bulk alloys with ultra-high strength and enhanced ductility

2004 ◽  
Vol 851 ◽  
Author(s):  
Dmitri V. Louzguine-Luzgin ◽  
Larissa V. Louzguina-Luzgina ◽  
Hidemi Kato ◽  
Akihisa Inoue
Keyword(s):  
Solid Solution ◽  
Supersaturated Solid Solution ◽  
High Strength ◽  
Eutectic Structure ◽  
Solution Phase ◽  
Solid Solution Phase ◽  
Mechanical Fracture ◽  
Glassy Alloys ◽  
Fe Alloys ◽  
Bulk Alloys

ABSTRACTThe high-strength and ductile hypo-, hyper- and eutectic Ti-Fe alloys were formed in the shape of the arc-melted ingots with the dimensions of about 25–40 mm in diameter and 10–15 mm in height. The structure of the samples consists of cubic Pm 3 m TiFe and BCC Im 3 m β-Ti supersaturated solid solution phase. The arc-melted hypereutectic Ti65Fe35 alloy has a dispersed structure consisting of the primary TiFe phase and submicron-size eutectic structure. This alloy exhibits excellent mechanical properties: a Young's modulus of 149 GPa, a high mechanical fracture strength of 2.2 GPa, a 0.2 % yield strength of 1.8 GPa and 6.7 % ductility. The hard round-shaped intermetallic TiFe phase and the supersaturated β-Ti solid solution result in a high strength of the Ti65Fe35 alloy which in addition has much higher ductility compared to that of the nanostructured or glassy alloys. The reasons for the high ductility of the hypereutectic alloy are discussed.

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