Electronic Packaging Materials
Editor's Note
The integrated circuit industry is the core of the information technology industry. It is a basic but strategic and leading industry that supports economic and social development and guarantees national security, while electronic packaging materials and technologies are the premise and key to the sustainable development of integrated circuit industry. This thematic issue covers the development and application of key materials closely related to electronic packaging technology, including flip chip packaging materials and technologies, thermal conductive materials, organic packaging substrates, low melting point solders, temporary bonding glues, LED device packaging materials, as well as embedded capacitor material technology, testing, and device design, etc. Going through this thematic issue, readers will learn more about the efforts made by Chinese researchers and scholars active in the forefront of electronic packaging technology materials, and have a preliminary understanding of current level and future development trends of electronic packaging materials.
Guest Editor
Rong Sun Professor
Director of Center for Advanced Materials and Institute of Advanced Materials Science and Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
Prof. Sun’s research focuses on the key materials for electronic packaging.
Chingping Wong, Professor, Academician of American Academy of Engineering, Foreign Academician of Chinese Academy of Engineering
Department of Electronics Engineering, The Chinese University of Hong Kong, Hong Kong,China
Prof. Wang’s research focuses on high-density electronic packaging materials.
Article List
2014, 3(6):1-7.
DOI: 10.12146/j.issn.2095-3135.201406001
Abstract:
LED is the abbreviation of light emitting diode, which is a kind of semiconductor materials that can transform electrical energy into visible light. With the improvement of LED brightness and efficiency, the die bonding materials have become one of the key technologies which are used to deal with heat management for LED. In this paper, the types, characteristics and development of LED die bonding materials developed for the performance requirements of LED packaging, especially the epoxy and silicone materials, were summarized.
LED is the abbreviation of light emitting diode, which is a kind of semiconductor materials that can transform electrical energy into visible light. With the improvement of LED brightness and efficiency, the die bonding materials have become one of the key technologies which are used to deal with heat management for LED. In this paper, the types, characteristics and development of LED die bonding materials developed for the performance requirements of LED packaging, especially the epoxy and silicone materials, were summarized.
2014, 3(6):8-13.
DOI: 10.12146/j.issn.2095-3135.201406002
Abstract:
The ac conductivity and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics were investigated in a temperature range of －120℃ to 300℃ and a frequency range of 1 Hz to 10 MHz. Two different conduction processes, which can be well described by Mott’s variable-range-hopping (VRH) mechanism, were observed in different temperature regions. The high temperature VRH conduction is related to the second ionization of oxygen vacancy. The low temperature dielectric properties of CCTO could be described by the so-called universal dielectric response (UDR) when a polaron relaxation is considered.
The ac conductivity and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics were investigated in a temperature range of －120℃ to 300℃ and a frequency range of 1 Hz to 10 MHz. Two different conduction processes, which can be well described by Mott’s variable-range-hopping (VRH) mechanism, were observed in different temperature regions. The high temperature VRH conduction is related to the second ionization of oxygen vacancy. The low temperature dielectric properties of CCTO could be described by the so-called universal dielectric response (UDR) when a polaron relaxation is considered.
4 Fabrication and Characterization of Embedded Capacitors in PCB Using Epoxy/BaTiO3/PI Capacitor CCL
2014, 3(6):14-22.
DOI: 10.12146/j.issn.2095-3135.201406003
Abstract:
The embedded capacitors in PCB (Printed Circuit Board) were fabricated using commercial epoxy/BaTiO3/PI capacitor CCL in conventional PCB build-up process. Capacitance measuring demonstrated the tolerances of the obtained capacitors ranged from －4.0% to －6.0%, and special design to compensate the capacitor geometry significantly decreased the tolerance to －1.1%. Reflow process at 260℃, high thermal cycling, 85℃/85% RH and high-voltage breakdown tests were performed to evaluate the reliability of embedded capacitors. It is summarized that the fabrication of epoxy/BaTiO3/ PI composite embedded capacitors is successfully demonstrated using conventional PCB build-up processes, and their environmental reliability are evaluated to be excellent.
The embedded capacitors in PCB (Printed Circuit Board) were fabricated using commercial epoxy/BaTiO3/PI capacitor CCL in conventional PCB build-up process. Capacitance measuring demonstrated the tolerances of the obtained capacitors ranged from －4.0% to －6.0%, and special design to compensate the capacitor geometry significantly decreased the tolerance to －1.1%. Reflow process at 260℃, high thermal cycling, 85℃/85% RH and high-voltage breakdown tests were performed to evaluate the reliability of embedded capacitors. It is summarized that the fabrication of epoxy/BaTiO3/ PI composite embedded capacitors is successfully demonstrated using conventional PCB build-up processes, and their environmental reliability are evaluated to be excellent.
2014, 3(6):23-28.
DOI: 10.12146/j.issn.2095-3135.201406004
Abstract:
Homogeneous Cu6Sn5 and Cu3Sn joints were formed in Cu/Sn foil/Cu interconnection system respectively, using ultrasonic bonding process for a short period of 3 seconds at room temperature. This ultrarapid development of full intermetallic compound (IMC) joints required an accelerated interdiffusion kinetics at the interface between liquid Sn and solid Cu which could be wholly attributed to the sonochemical effects induced by acoustic cavitation phenomenon. When bubble collapsed near the liquid/solid interface, excessive cavitation erosion was generated on the solid Cu surface, resulting in supersaturation of Cu in the liquid Sn and hence facilitating the formation of intermetallic phases as chemical reaction products. The resulted intermetallic joints performed high mechanical reliability.
Homogeneous Cu6Sn5 and Cu3Sn joints were formed in Cu/Sn foil/Cu interconnection system respectively, using ultrasonic bonding process for a short period of 3 seconds at room temperature. This ultrarapid development of full intermetallic compound (IMC) joints required an accelerated interdiffusion kinetics at the interface between liquid Sn and solid Cu which could be wholly attributed to the sonochemical effects induced by acoustic cavitation phenomenon. When bubble collapsed near the liquid/solid interface, excessive cavitation erosion was generated on the solid Cu surface, resulting in supersaturation of Cu in the liquid Sn and hence facilitating the formation of intermetallic phases as chemical reaction products. The resulted intermetallic joints performed high mechanical reliability.
2014, 3(6):29-35.
DOI: 10.12146/j.issn.2095-3135.201406005
Abstract:
Graphitized porous carbon microspheres/paraffin composite phase change materials were prepared which could be used for the thermal management. KOH was introduced to help carbon microspheres to form the porous structure. The porous carbon microspheres exhibited good sphericity, abundant pores and large surface area, which would be more convenient to absorb the paraffin. The porous carbon microspheres were treated under different temperatures using Fe(NO3)3 as catalyst to investigate the degree of graphitization. The graphitization temperature played an important role in improving the thermal conductivity of the phase change composite.
Graphitized porous carbon microspheres/paraffin composite phase change materials were prepared which could be used for the thermal management. KOH was introduced to help carbon microspheres to form the porous structure. The porous carbon microspheres exhibited good sphericity, abundant pores and large surface area, which would be more convenient to absorb the paraffin. The porous carbon microspheres were treated under different temperatures using Fe(NO3)3 as catalyst to investigate the degree of graphitization. The graphitization temperature played an important role in improving the thermal conductivity of the phase change composite.
2014, 3(6):36-44.
DOI: 10.12146/j.issn.2095-3135.201406006
Abstract:
Thermal interface material (TIM) technology is of great importance in the 3D system packaging. In this paper, the preparation of thermal interface materials using vertically aligned carbon nanotube (VACNT) array and its characterization were investigated. The transfer process of VACNT was successfully performed by a Ti/Ni/Au metal layer with a thickness of 50/100/100 nm and Sn64Bi35Ag1 solder. A thermal release adhesive tape (Nitto Denko, Part Number: #3198MS) was used to obtain suspended VACNT array. The LFA 447 was used to characterize the thermal diffusivity α(T) and apparent thermal conductivity λ(T) of VACNT array at 25℃, 75℃ and 125℃, respectively. Thermal cycle reliability test was also carried out. Results show that the apparent λ(T) is over 42 W/(m·K) for VACNT array on the Si growth substrate and over 41 W/(m·K) for transferred CNT array. After 200 thermal cycles, the λ(T) is over 28 W/(m·K) for CNT array on its Si growth substrate and over 24 W/(m·K) for transferred CNT array.
Thermal interface material (TIM) technology is of great importance in the 3D system packaging. In this paper, the preparation of thermal interface materials using vertically aligned carbon nanotube (VACNT) array and its characterization were investigated. The transfer process of VACNT was successfully performed by a Ti/Ni/Au metal layer with a thickness of 50/100/100 nm and Sn64Bi35Ag1 solder. A thermal release adhesive tape (Nitto Denko, Part Number: #3198MS) was used to obtain suspended VACNT array. The LFA 447 was used to characterize the thermal diffusivity α(T) and apparent thermal conductivity λ(T) of VACNT array at 25℃, 75℃ and 125℃, respectively. Thermal cycle reliability test was also carried out. Results show that the apparent λ(T) is over 42 W/(m·K) for VACNT array on the Si growth substrate and over 41 W/(m·K) for transferred CNT array. After 200 thermal cycles, the λ(T) is over 28 W/(m·K) for CNT array on its Si growth substrate and over 24 W/(m·K) for transferred CNT array.
2014, 3(6):45-51.
DOI: 10.12146/j.issn.2095-3135.201406007
Abstract:
MnO2 was deposited on Ni nanocone arrays through electrochemical deposition process, to enhance the electrochemical performance. The as-prepared MnO2/Ni nanocone electrode can be peeled off from the substrate and used as freestanding, flexible, and ultrathin supercapacitor electrode. Its specific capacitance is as high as 325 F/g. The electrode also shows excellent rate performance. The flexible and ultrathin asymmetric supercapacitor based on the MnO2/ Ni nanocone elelctrode demostrates good electrochemical performance. The device possesses promising applications in the field of energy storage.
MnO2 was deposited on Ni nanocone arrays through electrochemical deposition process, to enhance the electrochemical performance. The as-prepared MnO2/Ni nanocone electrode can be peeled off from the substrate and used as freestanding, flexible, and ultrathin supercapacitor electrode. Its specific capacitance is as high as 325 F/g. The electrode also shows excellent rate performance. The flexible and ultrathin asymmetric supercapacitor based on the MnO2/ Ni nanocone elelctrode demostrates good electrochemical performance. The device possesses promising applications in the field of energy storage.
2014, 3(6):52-62.
DOI: 10.12146/j.issn.2095-3135.201406008
Abstract:
Polyaniline deposited BaTiO3 hybrid nanoparticles (BT@PANI) were synthesized via in-situ polymerization process and then used as fillers to fabricate the BT@PANI/epoxy composites. The dielectric constant of the composites increased with the increment of PANI in BT@PANI(while the fraction of BT decreased in the composite), which was attributed to the enhanced interfacial polarization induced by the conducting PANI. The value of k increased from 17 for 0 wt% PANI to 53 for 26 wt% PANI. No typical percolation effect was observed in the composite and when the content of PANI in the BT@PANIreached 26 wt%, the conductivity maintained a low value of 1.64×10－6 S/m. Besides, the dielectric constant of the composites jumped remarkably inthe measured temperature range from 60℃ to 100℃ as anevidenceof the stronger interfacial polarization generated by conducting PANI with temperature increasing, theenhanced motion of epoxy molecule chains around Tg (90℃)and the phase transition of BT near the curie point 120℃.
Polyaniline deposited BaTiO3 hybrid nanoparticles (BT@PANI) were synthesized via in-situ polymerization process and then used as fillers to fabricate the BT@PANI/epoxy composites. The dielectric constant of the composites increased with the increment of PANI in BT@PANI(while the fraction of BT decreased in the composite), which was attributed to the enhanced interfacial polarization induced by the conducting PANI. The value of k increased from 17 for 0 wt% PANI to 53 for 26 wt% PANI. No typical percolation effect was observed in the composite and when the content of PANI in the BT@PANIreached 26 wt%, the conductivity maintained a low value of 1.64×10－6 S/m. Besides, the dielectric constant of the composites jumped remarkably inthe measured temperature range from 60℃ to 100℃ as anevidenceof the stronger interfacial polarization generated by conducting PANI with temperature increasing, theenhanced motion of epoxy molecule chains around Tg (90℃)and the phase transition of BT near the curie point 120℃.
2014, 3(6):63-75.
DOI: 10.12146/j.issn.2095-3135.201406009
Abstract:
The inorganic particles filled polymer composites have attracted considerable interests because of their good mechanical properties and tailorable performances by controlling the content of the filler. The polymer composites with high permittivity by introducing high dielectric constant ceramics or conducting nanoparticles into the polymer matrix have shown tremendous application foreground. This review focuses on the progress of inorganic/polymer composites and permeability of composite on the performance of embedded passive devices were also investigated. applications in embedded passive devices in recently years. The design and fabrication of the embedded capacitor,inductor and filter based on the Inorganic/Polymer composite were discussed. The effects of parameters including permittivity and
The inorganic particles filled polymer composites have attracted considerable interests because of their good mechanical properties and tailorable performances by controlling the content of the filler. The polymer composites with high permittivity by introducing high dielectric constant ceramics or conducting nanoparticles into the polymer matrix have shown tremendous application foreground. This review focuses on the progress of inorganic/polymer composites and permeability of composite on the performance of embedded passive devices were also investigated. applications in embedded passive devices in recently years. The design and fabrication of the embedded capacitor,inductor and filter based on the Inorganic/Polymer composite were discussed. The effects of parameters including permittivity and
2014, 3(6):76-83.
DOI: 10.12146/j.issn.2095-3135.201406010
Abstract:
The main functions of substrates in electronic packaging include supporting, cooling, protection of semiconductor chips, as well as insulation and electronic interconnection with external chips. With the electronic packaging developing towards high speed, multi-functionalization, high performance, good stability and small dimension, substrates play more and more important role in the field of new generation electronics packaging. Scientists and engineers have higher requirement to substrate materials, which advances their brilliant progress. In this review, the characteristic, recent progress and future development of three kinds of substrates were summerized, including ceramic, composite and organic substrates.
The main functions of substrates in electronic packaging include supporting, cooling, protection of semiconductor chips, as well as insulation and electronic interconnection with external chips. With the electronic packaging developing towards high speed, multi-functionalization, high performance, good stability and small dimension, substrates play more and more important role in the field of new generation electronics packaging. Scientists and engineers have higher requirement to substrate materials, which advances their brilliant progress. In this review, the characteristic, recent progress and future development of three kinds of substrates were summerized, including ceramic, composite and organic substrates.
2014, 3(6):84-91.
DOI: 10.12146/j.issn.2095-3135.201406011
Abstract:
As the high density package is moving towards miniaturization, high I/O density, better thermal and high reliable system, the conventional wire bonding technology can not satisfy the product need already. The advanced flip chip technology is highly expected due to its high area array I/O interconnection, short signal path, high thermal dissipation, high electrical and thermal performance. In order to enhance the reliability of a flip-chip on organic board package, underfill is used between the chip and the substrate to redistribute the thermo-mechanical stress created by the coefficient of thermal expansion (CTE) mismatch between the silicon chip and organic substrate. However, the conventional underfill relies on the capillary flow of the underfill material and has many disadvantages. In order to overcome these disadvantages, no-flow underfill has been invented to improve the flip-chip underfill process. This paper reviews the development of flipchip technology and expounds the behavior of flow and no-flow underfill.
As the high density package is moving towards miniaturization, high I/O density, better thermal and high reliable system, the conventional wire bonding technology can not satisfy the product need already. The advanced flip chip technology is highly expected due to its high area array I/O interconnection, short signal path, high thermal dissipation, high electrical and thermal performance. In order to enhance the reliability of a flip-chip on organic board package, underfill is used between the chip and the substrate to redistribute the thermo-mechanical stress created by the coefficient of thermal expansion (CTE) mismatch between the silicon chip and organic substrate. However, the conventional underfill relies on the capillary flow of the underfill material and has many disadvantages. In order to overcome these disadvantages, no-flow underfill has been invented to improve the flip-chip underfill process. This paper reviews the development of flipchip technology and expounds the behavior of flow and no-flow underfill.
2014, 3(6):92-101.
DOI: 10.12146/j.issn.2095-3135.201406012
Abstract:
As a potential new generation display technology, OLED has many advantages such as light weight, wide visual angle, quick response, high luminous efficiency and low cost. The research and development of OLED encapsulation materials is to prevent corrosion by oxygen and moisture from the external environment and prolong the lifetime of organic emitting materials. Besides excellent barrier properties, OLED encapsulation materials also require good thermal conductivity, luminousness, mechanical strength, corrosion resistance and good adhesion to substrate and so on. In this paper, the development of OLED encapsulation materials was introduced in detail which cover the metal, glass and ceramic used for conventional encapsulation and inorganic compounds, polymers and composite materials used for the thin film encapsulation. The development direction of OLED encapsulation materials based on the demands of packaging methods in future was also discussed.
As a potential new generation display technology, OLED has many advantages such as light weight, wide visual angle, quick response, high luminous efficiency and low cost. The research and development of OLED encapsulation materials is to prevent corrosion by oxygen and moisture from the external environment and prolong the lifetime of organic emitting materials. Besides excellent barrier properties, OLED encapsulation materials also require good thermal conductivity, luminousness, mechanical strength, corrosion resistance and good adhesion to substrate and so on. In this paper, the development of OLED encapsulation materials was introduced in detail which cover the metal, glass and ceramic used for conventional encapsulation and inorganic compounds, polymers and composite materials used for the thin film encapsulation. The development direction of OLED encapsulation materials based on the demands of packaging methods in future was also discussed.
2014, 3(6):102-110.
DOI: 10.12146/j.issn.2095-3135.201406013
Abstract:
3D integrated circuits (3D-ICs) by stacking electronic devices can increase system capacity and functionality while decreasing the overall footprint. Through-silicon via (TSV) technology based on thin wafers (typically below 100 μm) has been developed to realize 3D-IC packaging over the last decades. Due to their fragileness and tendency of warping, thin device wafer needs to be bonded firmly to a carrier wafer during TSV processing and readily separated from the carrier after processing. The present research situation of temporary adhesive used in this processing was introduced in this paper, and the properties of a novel temporary adhesive based on thermoplastic resin were investigated systematically. This novel adhesive possesses excellent rheological properties, thermal stability, chemical resistance and sufficient bonding strength, and convenient post-processing. These results extend the candidate polymers for temporary bonding materials and can ultimately promote the practical application of the TSV technology.
3D integrated circuits (3D-ICs) by stacking electronic devices can increase system capacity and functionality while decreasing the overall footprint. Through-silicon via (TSV) technology based on thin wafers (typically below 100 μm) has been developed to realize 3D-IC packaging over the last decades. Due to their fragileness and tendency of warping, thin device wafer needs to be bonded firmly to a carrier wafer during TSV processing and readily separated from the carrier after processing. The present research situation of temporary adhesive used in this processing was introduced in this paper, and the properties of a novel temporary adhesive based on thermoplastic resin were investigated systematically. This novel adhesive possesses excellent rheological properties, thermal stability, chemical resistance and sufficient bonding strength, and convenient post-processing. These results extend the candidate polymers for temporary bonding materials and can ultimately promote the practical application of the TSV technology.
