Maintaining Low Voiding Solder Die Attach for Power Die While Minimizing Die Tilt

This paper addresses work to minimize voiding and die tilt in solder attachment of a large power die, measuring 9.0 mm × 6.5 mm × 0.1 mm (0.354″ × 0.256″ × 0.004″), to a heat spreader. As demands for larger high power die continue, minimizing voiding and die tilt is of interest for improved die functionality, yield, manufacturability, and reliability. High-power die generate considerable heat, which is important to dissipate effectively through control of voiding under high thermal load areas of the die while maintaining a consistent bondline (minimizing die tilt). Voiding was measured using acoustic imaging and die tilt was measured using two different optical measurement systems. 80Au-20Sn solder reflow was achieved using a batch vacuum solder system with optimized fixturing. Minimizing die tilt proved to be the more difficult of the two product requirements to meet. Process development variables included tooling, weight and solder preform thickness.

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Thermal and Mechanical Characterization of High Power GaN Packages

International Symposium on Microelectronics ◽

10.4071/isom-2011-tp5-paper2 ◽

2011 ◽

Vol 2011 (1) ◽

pp. 000361-000366

Author(s):

Don Willis ◽

Gary Gu ◽

Daniel Jin ◽

Rob Dry

Keyword(s):

Thermal Performance ◽

High Power ◽

Mechanical Analysis ◽

Heat Spreader ◽

Element Analysis ◽

Die Attach ◽

Viable Solution ◽

Alternative Approach ◽

Thermal Improvement ◽

Multiple Devices

The typical package available for high power GaN application has the devices directly attached onto a metal flange, which could contribute significantly to the overall thermal resistance. This paper discusses an alternative approach to packaging both single and multiple devices through a heat spreader, which could potentially improve thermal performance and bring significant benefits to assembly in yields and cost. However, the heat spreader could also introduce significant CTE mis-match and potential concerns in reliability. Nonlinear 3D finite element analysis (FEA) was conducted to characterize the thermal performance and evaluate mechanical/reliability concerns. Thermal modeling considered single and multiple die applications, and the results show13–15% thermal improvement with the copper heat spreader. Mechanical analysis focused on the thermal loads of the die attach and solder reflow processes. It reveals that the die attach process is more critical as shown in the higher stress due to higher thermal load, but stress/strain levels appear to be acceptable. Thus, this alternative approach could be a viable solution.

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High-power LED light sources for optical measurement systems operated in continuous and overdriven pulsed modes

10.1117/12.2270304 ◽

2017 ◽

Cited By ~ 1

Author(s):

Bolesław Stasicki ◽

Andreas Schröder ◽

Fritz Boden ◽

Krzysztof Ludwikowski

Keyword(s):

High Power ◽

Optical Measurement ◽

Light Sources ◽

Led Light ◽

Measurement Systems ◽

High Power Led

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Nano-imprinted subwavelength gratings as polarizing beamsplitters

Journal of the European Optical Society Rapid Publications ◽

10.1186/s41476-021-00149-8 ◽

2021 ◽

Vol 17 (1) ◽

Author(s):

Julian Wüster ◽

Yannick Bourgin ◽

Patrick Feßer ◽

Arne Behrens ◽

Stefan Sinzinger

Keyword(s):

Nanoimprint Lithography ◽

Optical Measurement ◽

Design Method ◽

Optical Systems ◽

Surface Metrology ◽

Measurement Systems ◽

Common Path ◽

Dielectric Coatings ◽

Subwavelength Gratings ◽

Wide Range

AbstractPolarizing beamsplitters have numerous applications in optical systems, such as systems for freeform surface metrology. They are classically manufactured from birefringent materials or with stacks of dielectric coatings. We present a binary subwavelength-structured form-birefringent diffraction grating, which acts as a polarizing beamsplitter for a wide range of incidence angles −30∘…+30∘. We refine the general design method for such hybrid gratings. We furthermore demonstrate the manufacturing steps with Soft-UV-Nanoimprint-Lithography, as well as the experimental verification, that the structure reliably acts as a polarizing beamsplitter. The experimental results show a contrast in efficiency for TE- and TM-polarization of up to 1:18 in the first order, and 34:1 in the zeroth order. The grating potentially enables us to realize integrated compact optical measurement systems, such as common-path interferometers.

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Detection of foot contact in treadmill running with inertial and optical measurement systems

Journal of Biomechanics ◽

10.1016/j.jbiomech.2021.110419 ◽

2021 ◽

pp. 110419

Author(s):

Jasper Reenalda ◽

Marit A. Zandbergen ◽

Jelle D. Harbers ◽

Max R. Paquette ◽

Clare E. Milner

Keyword(s):

Optical Measurement ◽

Treadmill Running ◽

Measurement Systems

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Reliability of High-Power Light Emitting Diode Attached With Different Thermal Interface Materials

Journal of Electronic Packaging ◽

10.1115/1.4002299 ◽

2010 ◽

Vol 132 (3) ◽

Cited By ~ 23

Author(s):

Xin Li ◽

Xu Chen ◽

Guo-Quan Lu

Keyword(s):

High Power ◽

Heat Dissipation ◽

Light Emitting Diode ◽

Temperature Cycling ◽

Fluorescent Light ◽

Light Sources ◽

Light Emitting ◽

Die Attach ◽

Nanosilver Paste ◽

Interconnection Material

As a solid electroluminescent source, white light emitting diode (LED) has entered a practical stage and become an alternative to replace incandescent and fluorescent light sources. However, due to the increasing integration and miniaturization of LED chips, heat flux inside the chip is also increasing, which puts the packaging into the position to meet higher requirements of heat dissipation. In this study, a new interconnection material—nanosilver paste is used for the LED chip packaging to pursue a better optical performance, since high thermal conductivity of this material can help improve the efficiency of heat dissipation for the LED chip. The bonding ability of this new die-attach material is evaluated by their bonding strength. Moreover, high-power LED modules connected with nanosilver paste, Sn3Ag0.5Cu solder, and silver epoxy are aged under hygrothermal aging and temperature cycling tests. The performances of these LED modules are tested at different aging time. The results show that LED modules sintered with nanosilver paste have the best performance and stability.

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Methods of temperature measurement in microwave heating technologies

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2021-6-20-28 ◽

2021 ◽

pp. 20-28

Author(s):

Boris A. Lapshinov

Keyword(s):

Temperature Measurement ◽

Microwave Heating ◽

Microwave Radiation ◽

Electromagnetic Fields ◽

Optical Measurement ◽

Measurement Methods ◽

Heating Systems ◽

Measurement Systems ◽

Processed Material ◽

Spectral Pyrometry

In industrial technological processes associated with the heating of the processed material by microwave radiation, it is necessary to measure the temperatures of objects. Methods for measuring temperatures in the fields of technology using microwave heating systems are considered. The main possibilities, disadvantages and limitations of the used contact and non-contact (optical) measurement methods are determined. The requirements for temperature measurement systems under conditions of exposure to strong electromagnetic fields are listed. The possibilities of the spectral pyrometry method are especially noted.

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Multi-layered tissue head phantoms for noninvasive optical diagnostics

Journal of Innovative Optical Health Sciences ◽

10.1142/s1793545815410059 ◽

2015 ◽

Vol 08 (03) ◽

pp. 1541005 ◽

Cited By ~ 39

Author(s):

M. S. Wróbel ◽

A. P. Popov ◽

A. V. Bykov ◽

M. Kinnunen ◽

M. Jędrzejewska-Szczerska ◽

...

Keyword(s):

Optical Properties ◽

Near Infrared ◽

Optical Measurement ◽

Human Head ◽

Medical Diagnostics ◽

Optical Parameters ◽

Measurement Systems ◽

Tissue Phantoms ◽

Optical And Mechanical Properties

Extensive research in the area of optical sensing for medical diagnostics requires development of tissue phantoms with optical properties similar to those of living human tissues. Development and improvement of in vivo optical measurement systems requires the use of stable tissue phantoms with known characteristics, which are mainly used for calibration of such systems and testing their performance over time. Optical and mechanical properties of phantoms depend on their purpose. Nevertheless, they must accurately simulate specific tissues they are supposed to mimic. Many tissues and organs including head possess a multi-layered structure, with specific optical properties of each layer. However, such a structure is not always addressed in the present-day phantoms. In this paper, we focus on the development of a plain-parallel multi-layered phantom with optical properties (reduced scattering coefficient [Formula: see text] and absorption coefficient μa) corresponding to the human head layers, such as skin, skull, and gray and white matter of the brain tissue. The phantom is intended for use in noninvasive diffuse near-infrared spectroscopy (NIRS) of human brain. Optical parameters of the fabricated phantoms are reconstructed using spectrophotometry and inverse adding-doubling calculation method. The results show that polyvinyl chloride-plastisol (PVCP) and zinc oxide ( ZnO ) nanoparticles are suitable materials for fabrication of tissue mimicking phantoms with controlled scattering properties. Good matching was found between optical properties of phantoms and the corresponding values found in the literature.

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