How to pressureless sinter-bond power chips with bare copper substrates using nanosilver paste?

2019 ◽  
Author(s):  
Yue Chen ◽  
Yunhui. Mei ◽  
Zhihong Feng ◽  
Panpan Lu ◽  
Meiyu Wang ◽  
...  
Keyword(s):  
Pressureless Sinter ◽  
Nanosilver Paste ◽  
Bare Copper

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

2010 ◽  
Vol 132 (3) ◽  
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.

Flip-chip soldering to bare copper circuits

1990 ◽  
Vol 13 (4) ◽  
pp. 656-660 ◽  
Author(s):  
A.P. Ingraham ◽  
J.M. McCreary ◽  
J.A. Varcoe
Keyword(s):  
Flip Chip ◽  
Bare Copper

Improved Heat Dissipation and Optical Performance of High-power LED Packaging with Sintered Nanosilver Die-attach Material

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 001585-001605 ◽  
Author(s):  
Paul Panaccione ◽  
Tao Wang ◽  
Guo-Quan Lu ◽  
Xu Chen ◽  
Susan Luo
Keyword(s):  
Thermal Resistance ◽  
High Power ◽  
Heat Removal ◽  
High Current ◽  
Die Attach ◽  
High Power Led ◽  
Silver Epoxy ◽  
The Difference ◽  
Nanosilver Paste ◽  
The Impact

Heat removal in packaged high-power light-emitting diode (LED) chips is critical to device performance and reliability. Thermal performance of LEDs is important in that lowered junction temperatures extend the LED's lifetime at a given photometric flux (brightness). Optionally, lower thermal resistance can enable increased brightness operation without exceeding the maximum allowable Tj for a given lifetime. A significant portion of the junction-to-case thermal resistance comes from the joint between chip and substrate, or the die-attach layer. In this study, we evaluated three different types of leading die-attach materials; silver epoxy, lead-free solder, and an emerging nanosilver paste. Each of the three was processed via their respective physical and chemical mechanisms: epoxy curing by cross-linking of polymer molecules; intermetalic soldering by reflow and solidification; and nanosilver sintering by solid-state atomic diffusion. High-power LED chips with a chip area of 3.9 mm2 were attached by the three types of materials onto metalized aluminum nitride substrates, wire-bonded, and then tested in an electro-optical setup. The junction-to-heatsink thermal resistance of each LED assembly was determined by the wavelength shift methodology, described in detail in this paper. We found that the average thermal resistance in the chips attached by the nanosilver paste was the lowest, and it is the highest from the chips attached by the silver epoxy: the difference between the two was about 0.7°C/W, while the difference between the sintered and soldered was about 0.3°C/W. The lower thermal resistance in the sintered joints is expected to significantly improve the photometric flux from the device. Simple calculations, excluding high current efficiency droop, predict that the brightness improvement could be as high as 50% for the 3.9 mm2 chip. The samples will be functionally tested at high current, in both steady-state and pulsed operation, to determine brightness improvements, including the impact of droop. Nanosilver die-attach on a range of chip sizes up to 12 mm2 are also considered and discussed.

Aluminum Wedge-Wedge Bonding Using Capillary and Ball Bonder

2017 ◽  
Vol 2017 (1) ◽  
pp. 000444-000450
Author(s):  
Sarangapani Murali ◽  
Ei Phyu Phyu Theint ◽  
Hamdan Faizul Fitri ◽  
Tan Kean Tiong ◽  
Zhang Xi
Keyword(s):  
Gold Plating ◽  
Fine Ceramic ◽  
Cu Metallization ◽  
High Temperature Storage ◽  
Bonding Wires ◽  
Tensile Data ◽  
Substrate Surfaces ◽  
Wedge Bonding ◽  
Bare Copper ◽  
Temperature Storage

Abstract The paper discusses on the bondability and reliability of aluminum (Al) wedge-to-wedge bonding using fine ceramic capillary and ball bonder. Initial trials revealed aluminum build-up and poor capillary life with touch down of 20K or less. Optimizing the process parameters, switching on air-scrub, reducing shape angle to 20° instead of usual 35° and using Al-1wt%Si wire processed with refined grains revealed better capillary life with touch down of 200K without surface burrs. The method is capable of bonding complex looping and sharp acute bends. The data comprising of 1st and 2nd wedge dimensions, wedge pull, wedge shear and fracture mode for 20μm and 50μm Al-1wt%Si wires are presented. High temperature storage of aluminum wedge bonding to different substrate surfaces such as Al-0.5wt%Cu metallization, bare copper and gold plating revealed stable bond. From the wedge pull and tensile data, floor and shelf life of the wire is recommended to be 7days and 6months respectively. Evaluation of gold, copper and silver base bonding wires by this method showed feasible to bond and needs detailed studies to practice. The fusing current of Al-1wt%Si wire for varying diameter from 0.6 to 3mil and wire length from 1 to 20mm are also stated.

Critical Barriers Associated with Copper Wire

2015 ◽  
Vol 2015 (1) ◽  
pp. 000394-000398
Author(s):  
William G. Crockett
Keyword(s):  
High Reliability ◽  
Copper Wire ◽  
Automotive Electronics ◽  
Bonding Wire ◽  
Cu Alloy ◽  
Bonding Wires ◽  
Reducing Costs ◽  
Cu Bonding ◽  
Bonding Characteristics ◽  
Bare Copper

Since around 2008, the shift from Gold (Au) bonding wire to Copper (Cu) bonding wire has been taking place, full scale, with the aim of reducing costs. When compared with Au, Cu wire presents challenges in reliability and repeatable bonding characteristics in terms of chemical stability, which is required in high reliability applications. Therefore Cu wire adoption in automotive and industrial semiconductors has been limited. Conventionally the market for Cu bonding wires has been divided into two types: bare Cu wires (high purity) and Palladium coated copper (PCC) bonding wires. These wires have yet to satisfy the required characteristics for high reliability products such as industrial and automotive electronics. A new breed of alternative bonding wires has been developed to offer performance advantages for high reliability applications compared to bare copper wire and PCC wire. Cu alloy wire and Ag alloy wires continue their market introduction for advanced bonding applications, where bare Cu and PCC wires have known limitations.

Test Results of Sintered Nanosilver Paste Die Attach for High-Temperature Applications

2016 ◽  
Vol 13 (1) ◽  
pp. 6-16 ◽  
Author(s):  
Paul Croteau ◽  
Sayan Seal ◽  
Ryan Witherell ◽  
Michael Glover ◽  
Shashank Krishnamurthy ◽  
...  
Keyword(s):  
High Temperature ◽  
Cooling System ◽  
Wide Band ◽  
Power Converter ◽  
Test Results ◽  
Wide Band Gap ◽  
Strain Behavior ◽  
Die Attach ◽  
Nanosilver Paste ◽  
Sintered Silver

The emergence of wide band gap devices has pushed the boundaries of power converter operations and high power density applications. It is desirable to operate a power inverter at high switching frequencies to reduce passive filter weight and at high temperature to reduce the cooling system requirement. Therefore, materials and components that are reliable at temperatures ranging from −55°C to 200°C, or higher, are needed. Sintered silver is receiving significant attention in the power electronic industry. The porous nature of sintered nanosilver paste with a reduced elastic modulus has the potential to provide strain relief between the die component and substrate while maintaining its relatively high melting point after sintering. The test results presented herein include tensile testing to rupture of sintered silver film to characterize stress-strain behavior, as well as die shear and thermal cyclic tests of sintered silver-bonded silicon die specimens to copper substrates to determine shear strength and reliability.

scholarly journals Improvement of Sintering Performance of Nanosilver Paste by Tin Doping

2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Hui Yang ◽  
Jihui Wu
Keyword(s):  
Solid Solution ◽  
Shear Strength ◽  
Decomposition Temperature ◽  
Maximum Temperature ◽  
Joint Shear Strength ◽  
Solid Solution Strengthening ◽  
Strength Limit ◽  
Brittle Phase ◽  
Sintering Properties ◽  
Nanosilver Paste

Nanosilver paste, an interconnect solder, is a common choice in the electronics packaging industry. However, higher sintering temperature and lower sintering strength limit its application. At present, doped nanosilver paste has been studied for use in chip interconnection. In order to improve the sintering properties and shear strength of nanosilver paste, we have developed a new tin-doped nanosilver paste (referred to as silver tin paste), and according to the decomposition temperature of the organic dispersant in the slurry, a corresponding sintering process with a maximum temperature of 300°C was developed. The product after sintering of the silver tin paste is a mixture of a solid solution of Ag and an Ag3Sn phase. Among them, the hard and brittle phase Ag3Sn diffuse distribution in the silver matrix for strengthening, and the solid solution of Ag acts as a replacement solid solution strengthening. As the content of doped Sn increases, the sintering strength increases remarkably. When the Sn content is 5%, the joint shear strength reaches the highest value of 50 MPa. When it exceeds 5%, the sintering strength gradually decreases, which may be caused by the excessive formation of the intermetallic compound IMC as the dopant content increases. This new tin-doped nanosilver technology has the characteristics of low-temperature sintering and high-temperature service, so it is expected to be widely used in semiconductor power devices.

scholarly journals Experimental and Numerical Simulation Study of the Vibration Properties of Thin Copper Films Bonded to FR4 Composite

2020 ◽  
Vol 10 (15) ◽  
pp. 5197
Author(s):  
Sufyan A. Azam ◽  
Alex Fragoso
Keyword(s):  
Printed Circuit Boards ◽  
Copper Films ◽  
Circuit Boards ◽  
Good Correspondence ◽  
Printed Circuit ◽  
Modal Properties ◽  
Aspect Ratios ◽  
Different Diameters ◽  
First Time ◽  
Bare Copper

Printed circuit boards constitute the basis of most electronic devices and are mainly fabricated of thin copper films bounded to fiber epoxy laminates, such as FR4. Vibrational stress can induce device failure, and hence, studies addressing their modal properties have important applications. In this paper, cantilever samples made of bare copper bounded to FR4 have been studied to analyze, for the first time, the vibration behavior of specimens with different aspect ratios, with and without central holes of different diameters. Natural frequencies and damping ratios were determined experimentally and analytically using a finite element method for four groups of samples with a very good correspondence between both methods. The fundamental resonance frequency of all the specimens was found to be less than 40 Hz and the influence of a central hole was not significant to affect the modal properties.

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