Secondary IMC formation induced by Kirkendall voiding in Cu/Sn–3.5Ag solder joints

In this investigation on the formation of multiple-layered Kirkendall voids at Cu/Sn–3.5Ag solder joints, Sn–3.5Ag solder balls were reacted with Cu under bump metallurgy (UBM), which was electroplated using bis-sodium sulfopropyl–disulfide, C6H12O6S4Na2 (SPS) additive. The sequence of multilayer Kirkendall voids and Cu–Sn IMC (intermetallic compounds) formations are explained with the aid of cross-sectional scanning electron microscopy (SEM) micrographs and schematic diagrams. During the aging treatment at 150 °C, layers of Cu6Sn5/Cu3Sn formed at the solder joints and Kirkendall voids nucleated at the Cu3Sn/Cu interface as a result of the segregation of residual S originating from SPS. However, with Kirkendall void growth, the net section area of the Cu/Cu3Sn interface decreased and the Cu flux into Cu3Sn was inhibited. As the atomic ratio of Cu against Sn in the Cu3Sn dropped, transformation of Cu3Sn into Cu6Sn5 ensued. Subsequent diffusion of Sn atoms into the remaining Cu UBM through the remaining ligament of the Cu6Sn5/Cu interface precipitated secondary Cu3Sn beneath the primary Cu3Sn/Cu interface, and the secondary Kirkendall voids formed at the new Cu3Sn/Cu interface and so on.

Download Full-text

X-ray micro tomography in the scanning electron microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107678 ◽

1978 ◽

Vol 36 (1) ◽

pp. 106-107 ◽

Cited By ~ 1

Author(s):

W. Brünger

Keyword(s):

Electron Beam ◽

Electron Microscope ◽

Scanning Electron Microscope ◽

Target Surface ◽

The Body ◽

X Rays ◽

Cross Sectional ◽

X Ray ◽

Micro Tomography ◽

Scanning Electron

Reconstructive tomography is a new technique in diagnostic radiology for imaging cross-sectional planes of the human body /1/. A collimated beam of X-rays is scanned through a thin slice of the body and the transmitted intensity is recorded by a detector giving a linear shadow graph or projection (see fig. 1). Many of these projections at different angles are used to reconstruct the body-layer, usually with the aid of a computer. The picture element size of present tomographic scanners is approximately 1.1 mm2.Micro tomography can be realized using the very fine X-ray source generated by the focused electron beam of a scanning electron microscope (see fig. 2). The translation of the X-ray source is done by a line scan of the electron beam on a polished target surface /2/. Projections at different angles are produced by rotating the object.During the registration of a single scan the electron beam is deflected in one direction only, while both deflections are operating in the display tube.

Download Full-text

A Working Method for Adapting the (SEM) Scanning Electron Microscope to Produce (STEM) Scanning Transmission Electron Microscope Images

ISTFA 2002: Conference Proceedings from the 28th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2002p0093 ◽

2002 ◽

Author(s):

Edward Coyne

Keyword(s):

Electron Microscope ◽

High Resolution ◽

Scanning Electron Microscope ◽

Integrated Circuits ◽

Theoretical Idea ◽

Cross Sectional ◽

Additional Advantage ◽

Transmission Electron ◽

Resolution Element ◽

Scanning Electron

Abstract This paper describes the problems encountered and solutions found to the practical objective of developing an imaging technique that would produce a more detailed analysis of IC material structures then a scanning electron microscope. To find a solution to this objective the theoretical idea of converting a standard SEM to produce a STEM image was developed. This solution would enable high magnification, material contrasting, detailed cross sectional analysis of integrated circuits with an ordinary SEM. This would provide a practical and cost effective alternative to Transmission Electron Microscopy (TEM), where the higher TEM accelerating voltages would ultimately yield a more detailed cross sectional image. An additional advantage, developed subsequent to STEM imaging was the use of EDX analysis to perform high-resolution element identification of IC cross sections. High-resolution element identification when used in conjunction with high-resolution STEM images provides an analysis technique that exceeds the capabilities of conventional SEM imaging.

Download Full-text

The Influence of Blade Type and Feeding Force during Resin Bonded Dentin Specimen Preparation on the Microtensile Bond Strength Test

Micromachines ◽

10.3390/mi12040450 ◽

2021 ◽

Vol 12 (4) ◽

pp. 450

Author(s):

Apinya Limvisitsakul ◽

Suppason Thitthaweerat ◽

Pisol Senawongse

Keyword(s):

Bond Strength ◽

Surface Integrity ◽

Strength Test ◽

Specimen Preparation ◽

Sectional Area ◽

Microtensile Bond Strength ◽

Cross Sectional ◽

Microtensile Testing ◽

Feeding Force ◽

Scanning Electron

This paper presents the effect of blade type and feeding force during resin-bonded dentin specimen preparation on the microtensile bond strength (μTBS) test. Forty resin-bonded flat middle dentin specimens were divided into four groups. The specimens of each group were sectioned according to type of blade and feeding force as follows: fine grit/20 N, fine grit/40 N, medium grit/20 N, and medium grit/40 N to obtain resin-dentin sticks with a cross-sectional area of 1.0 mm2. Four sticks from the center of each tooth were subjected to the μTBS test. Five remaining sticks of each group were selected for surface topography observation under a scanning electron microscope (SEM). As a result, the bond strength of the medium-grit group was higher than that of the fine-grit group (p < 0.001), whereas the feeding force had no influence on bond strength values (p = 0.648). From the SEM, sticks prepared with the fine-grit blade showed a smoother surface integrity and fewer defects on the specimen edges in comparison with the sticks prepared with the medium-grit blade. The grit type of the blade is one of the considerable factors that may affect the bond strength and the surface integrity of resin-dentin specimens for microtensile testing.

Download Full-text

Revealing two distinctive intergranular cracking mechanisms of Ni-rich layered cathode by cross-sectional scanning electron microscopy

Journal of Power Sources ◽

10.1016/j.jpowsour.2021.230066 ◽

2021 ◽

Vol 503 ◽

pp. 230066

Author(s):

Haoqi Wu ◽

Changdong Qin ◽

Kuan Wang ◽

Xiao Han ◽

Manling Sui ◽

...

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Intergranular Cracking ◽

Cross Sectional ◽

Cracking Mechanisms ◽

Scanning Electron

Download Full-text

Localized thinning of GaAs/GaAlAs nanostructures by a combined scanning electron micrograph/focus ion beam system for high-quality cross-sectional transmission electron microscopy samples

Journal of Vacuum Science & Technology B Microelectronics Processing and Phenomena ◽

10.1116/1.586840 ◽

1993 ◽

Vol 11 (3) ◽

pp. 531 ◽

Cited By ~ 11

Author(s):

G. Ben Assayag

Keyword(s):

Electron Microscopy ◽

Ion Beam ◽

Electron Micrograph ◽

Scanning Electron Micrograph ◽

High Quality ◽

Cross Sectional ◽

Beam System ◽

Transmission Electron ◽

Focus Ion Beam ◽

Scanning Electron

Download Full-text

Characterization of Thin Polymer Blend Films using ESEM – No Charging, No Staining.

MRS Proceedings ◽

10.1557/proc-707-aa10.8.1/dd11.8.1 ◽

2001 ◽

Vol 707 ◽

Author(s):

Ian C. Bache ◽

Catherine M. Ramsdale ◽

D. Steve Thomas ◽

Ana-Claudia Arias ◽

J. Devin MacKenzie ◽

...

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Environmental Scanning Electron Microscopy ◽

Environmental Scanning ◽

Cross Sectional ◽

Blend Films ◽

Thin Polymer ◽

Device Applications ◽

Scanning Electron

ABSTRACTCharacterising the morphology of thin films for use in device applications requires the ability to study both the structure within the plane of the film, and also through its thickness. Environmental scanning electron microscopy has proved to be a fruitful technique for the study of such films both because contrast can be seen within the film without the need for staining (as is conventionally done for electron microscopy), and because cross-sectional images can be obtained without charging artefacts. The application of ESEM to a particular blend of relevance to photovoltaics is described.

Download Full-text

Effect of Design Parameters on Drop Test Performance of Wafer Level Chip Scale Packages (WLCSP)

ASME 2011 Pacific Rim Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Systems, MEMS and NEMS: Volume 1 ◽

10.1115/ipack2011-52078 ◽

2011 ◽

Author(s):

Pushkraj Tumne ◽

Vikram Venkatadri ◽

Santosh Kudtarkar ◽

Michael Delaus ◽

Daryl Santos ◽

...

Keyword(s):

Flip Chip ◽

Bulk Solder ◽

Consumer Electronics ◽

Drop Test ◽

Design Parameters ◽

Mechanical Shock ◽

Wafer Level ◽

Cross Sectional ◽

Right Censored Data ◽

Solder Balls

Today’s consumer market demands electronics that are smaller, faster and cheaper. To cater to these demands, novel materials, new designs, and new packaging technologies are introduced frequently. Wafer Level Chip Scale Package (WLCSP) is one of the emerging package technologies that have the key advantages of reduced cost and smaller footprint. The portable consumer electronics are frequently dropped; hence the emphasis of reliability is shifting towards study of effects of mechanical shock loading increasingly. Mechanical loading typically induces brittle fractures (also known as intermetallic failures) between the solder bumps and bond pads at the silicon die side. This type of failure mechanism is typically characterized by the board level drop test. WLCSP is a variant of the flip-chip interconnection technique. In WLCSPs, the active side of the die is inverted and connected to the PCB by solder balls. The size of these solder balls is typically large enough (300μm pre-reflow for 0.5mm pitch and 250μm pre-reflow for 0.4mm pitch) to avoid use of underfill that is required for the flip-chip interconnects. Several variations are incorporated in the package design parameters to meet the performance, reliability, and footprint requirements of the package assembly. The design parameters investigated in this effort are solder ball compositions with different Silver (Ag) content, backside lamination with different thickness, WLCSP type –Direct and Re-Distribution Layer (RDL), bond pad thickness, and sputtered versus electroplated Under Bump Metallurgy (UBM) deposition methods for 8×8, 9×9, and 10×10 array sizes. The test vehicles built using these design parameters were drop tested using JEDEC recommended test boards and conditions as per JESD22-B11. Cross sectional analysis was used to identify, confirm, and classify the intermetallic, and bulk solder failures. The objective of this research was to quantify the effects and interactions of WLCSP design parameters through drop test. The drop test data was collected and treated as a right censored data. Further, it was analyzed by fitting empirical distributions using the grouped and un-grouped data approach. Data analysis showed that design parameters had a significant effect on the drop performance and played a vital role in influencing the package reliability.

Download Full-text

An Analytical Method of Analyzing the Heat Conduction for the Unequal Cross-Section Straight Fin

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.365-366.1211 ◽

2013 ◽

Vol 365-366 ◽

pp. 1211-1216

Author(s):

Fan Zhang ◽

Peng Yun Song

Keyword(s):

Heat Conduction ◽

Cross Section ◽

Analytical Method ◽

Thermal Analyses ◽

Cross Sectional ◽

Cross Section Area ◽

Section Area ◽

Calculation Results ◽

The Cross ◽

Analytical Expressions

The cross-section area of straight fin is often considered to be equal in the thermal analyses of straight fin, but sometimes it is unequalin actual situation. Taking a straight fin with two unequal cross-sectional areas as an example,an analytical method of heat conduction for unequal section straight fin is presented. The analytical expressions of temperature field and heat dissipating capacity about the fin,which has a smaller cross-section area near the fin base and a larger one, is obtained respectively. The calculation results of the unequal cross-section are fully consistent with the equal area one, so the method is proved right. The results show that the larger the cross section areanear the base,the better is the heat transfer, and the temperature at the base with larger cross-section area is lower than that with smaller cross-section area when the amount of heat is fixed.

Download Full-text

Load bearing capacity of thin-walled rectangular and I-shaped steel sections of short both empty and concrete-filled columns

Frattura ed Integrità Strutturale ◽

10.3221/igf-esis.58.06 ◽

2021 ◽

Vol 15 (58) ◽

pp. 77-85

Author(s):

Amor Bouaricha ◽

Naoual Handel ◽

Aziza Boutouta ◽

Sarah Djouimaa

Keyword(s):

Cross Section ◽

Cross Sections ◽

Load Capacity ◽

Cross Sectional ◽

Short Columns ◽

Cross Section Area ◽

Section Area ◽

Specimen Height ◽

Steel Sections ◽

Thin Walled

In this experimental work, strength results obtained on short columns subjected to concentric loads are presented. The specimens used in the tests have made of cold-rolled, thin-walled steel. Twenty short columns of the same cross-section area and wall thickness have been tested as follows: 8 empty and 12 filled with ordinary concrete. In the aim to determine the column section geometry with the highest resistance, three different types of cross-sections have been compared: rectangular, I-shaped unreinforced and, reinforced with 100 mm spaced transversal links. The parameters studied are the specimen height and the cross-sectional steel geometry. The registered experimental results have been compared to the ultimate loads intended by Eurocode 3 for empty columns and by Eurocode 4 for compound columns. These results showed that a concrete-filled composite column had improved strength compared to the empty case. Among the three cross-section types, it has been found that I-section reinforced is the most resistant than the other two sections. Moreover, the load capacity and mode of failure have been influenced by the height of the column. Also, it had noted that the experimental strengths of the tested columns don’t agree well with the EC3 and EC4 results.

Download Full-text