Gap tolerant joining of aluminum with steel sheets using the hybrid technique

1992 ◽

Vol 50 (2) ◽

pp. 966-967

Author(s):

Thomas M. Moore

Keyword(s):

Integrated Circuit ◽

Acoustic Microscopy ◽

Hybrid Technique ◽

Frequency Scanning ◽

Ic Packaging ◽

Ic Package ◽

Microscopy Techniques ◽

Ic Package Inspection ◽

Pulse Echo ◽

Scanning Acoustic Microscope

In the last decade, a variety of characterization techniques based on acoustic phenomena have come into widespread use. Characteristics of matter waves such as their ability to penetrate optically opaque solids and produce image contrast based on acoustic impedance differences have made these techniques attractive to semiconductor and integrated circuit (IC) packaging researchers.These techniques can be divided into two groups. The first group includes techniques primarily applied to IC package inspection which take advantage of the ability of ultrasound to penetrate deeply and nondestructively through optically opaque solids. C-mode Acoustic Microscopy (C-AM) is a recently developed hybrid technique which combines the narrow-band pulse-echo piezotransducers of conventional C-scan recording with the precision scanning and sophisticated signal analysis capabilities normally associated with the high frequency Scanning Acoustic Microscope (SAM). A single piezotransducer is scanned over the sample and both transmits acoustic pulses into the sample and receives acoustic echo signals from the sample.

Download Full-text

Direct observation of Fe-Al-Zn ternary intermetallic compound and its transformation during the early stage of hot-dip galvanizing

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100151416 ◽

1993 ◽

Vol 51 ◽

pp. 1116-1117

Author(s):

C. S. Lin ◽

W. A. Chiou ◽

M. Meshii

Keyword(s):

Intermetallic Compound ◽

Reaction Rate ◽

Diffusion Rate ◽

Early Stage ◽

Zinc Bath ◽

Steel Sheets ◽

Direct Observations ◽

Solid Iron ◽

Iron And Zinc ◽

Ternary Intermetallic Compound

The galvannealed steel sheets have received ever increased attention because of their excellent post-painting corrosion resistance and good weldability. However, its powdering and flaking tendency during press forming processes strongly impairs its performance. In order to optimize the properties of galvanneal coatings, it is critical to control the reaction rate between solid iron and molten zinc.In commercial galvannealing line, aluminum is added to zinc bath to retard the diffusion rate between iron and zinc by the formation of a thin layer of Al intermetallic compound on the surface of steel at initial hot-dip galvanizing. However, the form of this compound and its transformation are still speculated. In this paper, we report the direct observations of this compound and its transformation.The specimens were prepared in a hot-dip simulator in which the steel was galvanized in the zinc bath containing 0.14 wt% of Al at a temperature of 480 °C for 5 seconds and was quenched by liquid nitrogen.

Download Full-text