fabrication of optimally micro-textured copper substrates

Aizawa, T. et al.

Paper:

Fabrication of Optimally Micro-Textured Copper Substratesby Plasma Printing for Plastic Mold Packaging

Tatsuhiko Aizawa∗,†, Yasuo Saito∗∗, Hideharu Hasegawa∗∗, and Kenji Wasa∗∗∗

∗Surface Engineering Design Laboratory3-15-10 Minami-rokugo, Ota, Tokyo 144-0045, Japan

†Corresponding author, E-mail: [email protected]∗∗Chuo Denshi Kogyo, Co., Ltd., Uki, Japan

∗∗∗MicroTeX Labs, LLC, Tokyo, Japan[Received June 27, 2019; accepted November 26, 2019]

Micro-embossing using plasma printed micro-punchwas proposed to form micro-groove textures into thecopper substrate for plastic packaging of hollowedGaN HEMT-chips. In particular, the micro-groovenetwork on the copper substrate was optimized to at-tain uniform stress distribution with maximum stresslevel being as low as possible. Three-dimensional fi-nite element analysis was employed to investigate theoptimum micro-grooving texture-topology and to at-tain the uniform stress distribution on the joined inter-face between the plastic mold and the textured coppersubstrate. Thereafter, plasma printing was utilized tofabricate the micro-punch for micro-embossing of themicro-grooving network into the copper substrate as adesigned optimum micro-texture. This plasma print-ing mainly consisted of three steps. Two-dimensionalmicro-pattern was screen-printed onto the AISI316die surface as a negative pattern of the optimum CADdata. The screen-printed die was plasma nitrided at673 K for 14.4 ks at 70 Pa under the hydrogen-nitrogenmixture for selective nitrogen supersaturation onto theunprinted die surfaces. A micro-punch was developedby mechanically removing the printed parts of die ma-terial. Then, fine computer numerical control (CNC)stamping was used to yield the micro-embossed cop-per substrate specimens. Twelve micro-textured sub-strates were molded into packaged specimens by plas-tic molding. Finally, gross leak testing was employedto evaluate the integrity of the joined interface. Thetakt time required to yield the micro-grooved coppersubstrate by the present method was compared to thepicosecond laser micro-grooving; the former showedhigh productivity based on this parameter.

Keywords: hollowed GaN chip, plastic molding, micro-texture optimization, micro-embossing, plasma printing

1. Introduction

The hollowed GaN high electron mobility transistor(HEMT) chip has applicabilities in radio frequency (RF)power module in 5G and satellite communications. In-stead of conventional ceramic packaging, plastic mold-ing is often employed as a packaging design owing to itscompatibility with various substrate materials [1]. In par-ticular, liquid crystal plastics (LCPs) have been widelyutilized for these hollowed packages to demonstrate thatthese are gross leak proof [2, 3]. Integrity in plastic mold-ing without use of chemical adhesions is strictly deter-mined by micro-texturing for interfacial joining of theplastics with the copper substrate. Initially, the fiber laseris utilized to form micro-grooves into the copper sub-strate [4]; this approach is accompanied by thermal dis-tortion (resulting in changes in geometry) and irregulari-ties at the groove edges. Secondly, the picosecond lasermicro-texturing [5] is applied to build fine micro-grooves(20 μm in width). Fine and complex shaped micro-textures are imprinted onto the copper substrate to preventgross leak [6]. However, the takt time for micro-texturingof each copper substrate is never less than 100 s; substan-tially higher takt time is required in the formation of morecomplex and deep micro-textures. In addition, studies thathave investigated laser micro-texturing for mass produc-tion are relatively less reliable.

Plasma printing for the fabrication of the multi-puncharray for the transcription of convex micro-textures in thestainless-steel dies to the metallic sheets and plates hasbeen proposed [7–9]. With the aid of the screen-printingand maskless lithography, the spatial resolution can beimproved from 20 μm up to 1 μm [10, 11]. In particu-lar, CAD data are directly transferred on a screen [10, 12];various micro-patterns can be tailored as screen films andtransformed to micro-dies as a common proof of relia-bility in mass production. CNC-stamping has been uti-lized for micro-embossing this plasma printed punch ar-ray onto the aluminium and copper plates [13, 14]. Underthe optimum loading and unloading sequence, fine micro-textured copper substrate as well as micro-pillared alu-minium heat-sink are produced with sufficient geometricaccuracy.

200 Int. J. of Automation Technology Vol.14 No.2, 2020


Fig. 1. Three-dimensional model of a plastic packagedchip unit. a) Overall model in this simulation and b) cross-sectional view along the line A–A’.

In the present paper, a new automatic procedure isproposed to tailor the optimum micro-textures for plas-tic packaging that are sufficiently leak proof, to fabricatethe micro-punch and -die by plasma printing, to coin themicro-groove network into the copper substrate via theCNC-stamper, and to develop plastic packaging throughthis micro-groove network for joining with the substrate.The gross leak testing is employed to demonstrate theleak-proof joinability between the plastic mold and cop-per substrate. This automatic production scheme usingplasma printing is effective in reducing the takt time sig-nificantly for plastic packaging with sufficient leak proofproperty.

2. Plastic Mold Packaging

2.1. Micro-Texture DesignThree-dimensional finite element analyses were per-

formed to estimate the stress distribution on the joined in-terface between the copper substrate and the plastic moldfor the optimization of micro-textures. Fig. 1 a) depictsthe three-dimensional CAD model of plastic-packagedchip unit. Micro-groove network is directly taken into ac-count in this simulation as shown in Fig. 1 b). For simplic-ity, the plastic mold is completely cemented to the coppersubstrate through the micro-groove surfaces to estimatethe interfacial stress distribution. In general, the inter-facial stresses concentrate along the edge of the micro-grooves under the uniaxial loading with tensile displace-ment. Hence, the optimum micro-groove network is de-fined by relaxing this stress concentration and loweringthe normal stress level as well as the stress transfer to theoutside of the network.

In the present study, two models were used to investi-gate the effect of micro-groove topology on the interfacialstress concentration. Fig. 2 a) shows the first model wherethe multi rectangular loops form a micro-groove networkon the interface. Each loop has sharp edge-angle with 90◦

Fig. 2. Two models of the micro-groove network in simula-tion. a) Model-1: micro-groove network by multi rectangu-lar loops, and b) Model-2: micro-groove network by multicurved loops and corner curved grooves.

at each corner. Fig. 2 b) depicts the second model, wherethe multi curved loops form a network together with a sin-gle curve groove at each corner. These loops have roundcurves at the four corners.

2.2. Plasma Printing ProcedurePlasma printing to fabricate the micro-punch for em-

bossing, consists of the following five steps.

1) CAD-data preparation for designing the initialmicro-pattern.

2) Transformation of CAD-data onto a screen.

3) Screen printing of this micro-pattern onto the diesubstrate.

4) Low temperature plasma nitriding.

5) Mechanical blasting to form micro-punch heads.

In the present study, screen printing is employed for theinitial micro-patterning onto the AISI316 die substrate.This die is plasma nitrided at 673 K for 14.4 ks at 70 Pafor selective nitrogen super-saturation down to the depthof 80 μm. Fine sand-blasting method is employed tomechanically remove the un-nitrided parts from the dieand to build up the multi-punch array for transcription ofmicro-textures onto the copper substrate.

2.3. Formation of Micro-Groove NetworkCNC stamper (Hoden Seimitsu Kako Kenkyusho, Co.,

Ltd., Atsugi, Japan) was utilized for micro-embossing themulti-punch array onto the copper specimen. First, themulti-punch array was fixed into a cassette die. This cas-sette die set was placed and fixed between the upper andlower bolsters. The loading sequence was programmed toexecute the optimum loading and unloading.

Int. J. of Automation Technology Vol.14 No.2, 2020 201

Aizawa, T. et al.

Table 1. Gross leak testing conditions.

Testing step ContentInitial leak testing Dipping to a depth of > 5 cm of

Fluorinert at 125◦C for 5 sPreliminary testing Holding at 125◦C for 24 h, and,

holding at 30◦C with 60% RHfor 192 h; three dip cyclesinto the infrared (IR)-reflow at260◦C

2.4. Plastic Molding ProcessThe lateral injection molding system was employed

to make plastic molding into the microtextured cop-per plates; thermoplastics were utilized in this molding.Twelve molded test-pieces were used for gross-leak test-ing.

2.5. Gross-Leak TestThe gross leak testing procedure is detailed in Table 1.

During testing, if no bubbles are detected during and af-ter each step, no leaks were verified. Twelve pieces weresubjected to similar testing to estimate the statistical prob-ability of the leak.

3. Experimental Results

A multi-punch array is first designed and fabricatedto explain how easily the tailored two-dimensional mi-cropatterns are transformed into a three-dimensionalmulti-punch array. This punch array is used to conductmicro-embossing onto the copper plates. Twelve texturedcopper substrates are molded to yield the specimens forgross leak testing.

3.1. Optimization of Micro-Grooving NetworkThree-dimensional finite element analysis was em-

ployed to estimate the stress distribution on the joined in-terface between the microtextured copper substrate andthe plastic mold. Fig. 3 depicts the stress distributionson the interface for the two models. In case of Model-1,higher normal stress was detected along the rectangu-lar loops including the stress concentration at the edges(Fig. 3 a)). It is to be noted that the plastic mold in theinside of the networks has much higher stresses. This re-veals that the micro-groove network in Model-1 is insuf-ficient to reduce the normal stress level. In fact, the edgeof the interface is also subjected to high stresses. Hence,how to reduce this normal stress level becomes an issue ofthis network design. In Model-2, the rectangular loop net-work was redesigned to have curved and wavy loops withround edges at each corner. In addition, a single curvedgroove was added to the outside of the loops. Fig. 3 b)depicts the normal stress distribution for this model. Thetopological change from linear micro-groove network to

Fig. 3. Calculated stress distribution on the joined interface.a) Model-1 and b) Model-2.

the curved one is responsible for uniform stress distribu-tion not only among the micro-grooved regions but also inthe inside of the loops. In addition, a single micro-grooveoutside the loops also contributes to lower the stress lev-els.

The optimum micro-grooving network is designed tohave multi curved loops from the outside to the inside ofthe interface and to have micro-grooves at the outside ofthese loop networks. This micro-groove network is alsomodified by relocation of curved loops and by changingthe wavy loops to curved ones with consideration of thefeasibility in manufacturing.

3.2. Micro-Punch by Plasma PrintingA screen film was first prepared to have a negative

micro-pattern to the CAD data (Fig. 4). The partsshown in black in Fig. 4 were selectively printed ontothe AISI316 die substrate, while the parts shown in whitewere shielded to prevent them from being printed. The



Fig. 4. Optimally designed micro-texture to fabricate thescreen for printing onto the AISI316 die surface.

Fig. 5. Plasma nitrided AISI316 die substrate after elimi-nating the printed masks.

screen printer (Newlong, Co., Ltd., Shinagawa, Japan)was used via manual operation. After [11, 13, 14], TiO2base ink was used to print the mask pattern onto AISI316substrate before nitriding. Its mechanical properties haveconsiderable influence on the spatial resolution in thepresent plasma printing; ink with a relatively high viscos-ity was utilized.

The unprinted AISI316 surfaces were selectively ni-trided and hardened while the masked die parts were notnitrided. Fig. 5 shows the nitrided die after slight blast-ing; blasting was performed to enhance the difference ingeometric configuration on the nitrided surface. The ni-trided loops as AISI316 heads in Fig. 5, correspond tothe micro-pattern in Fig. 4, respectively. Two line heads(A’ and B’) correspond to A and B; the double loop heads(C’ and D’) to C and D; triple loop heads (E’, F’, and G’)to E, F, and G; and inner double loop heads (H’ and K’)to H and K, respectively.

Figure 6 depicts the nitrogen mapping on the nitrided

Fig. 6. Nitrogen mapping on the nitrided die surface afterslightly blasting the masking ink.

Fig. 7. Fabricated micro-punch with multi-punch heads af-ter full blasting.

AISI316 die surface after removing the masking ink. Themicro-textured lines and loops (Fig. 6) have higher ni-trogen concentration than 9 mass%; while the maskedAISI316 die parts have nearly zero nitrogen concentra-tion. This high nitrogen concentration is common tothe selective nitrogen supersaturation of micro-nozzlesand micro-punches at low temperature [9, 13, 14]. In thepresent study, the unprinted lines and loops were selec-tively nitrogen super-saturated to attain sufficient hard-ness against mechanical blasting. That is, they are trans-formed to nitrided lines and loops with hardness higherthan that of the blasting media.

Since the silica particles with the hardness of 700 HVwere used for blasting, these nitrided networks with hard-ness higher than 1200 HV were left as a convex punchhead after blasting. Fig. 7 depicts the blasted AISI316die substrate after blasting for 300 s. Two linear heads(a and b) correspond to A and B in Fig. 4; double looped


Aizawa, T. et al.

Fig. 8. Plasma printed micro-punch with tailored micro-textures for micro-joining.

Fig. 9. Micro-embossed copper plate produced using themicro-punch array.

heads (c and d) to C and D; triple looped heads (e, f, and g)to E, F, and G; and double inner-looped heads (h and k)to H and K, respectively. That is, the printed parts areselectively removed by this blasting process. These headwidths are constant at 70 μm, which is broader than thedesigned and screened line width of 50 μm. This is be-cause TiO2 ink and film thickness were reduced at theedge of unit cells during nitriding. Uniform height of mi-cropunch heads proves that blasting took place homoge-neously. Fig. 8 depicts the plasma printed micropunchafter surface polishing. This punch was inserted into acassette die for micro-embossing via CNC-stamper witha linear scale to control the stroke.

3.3. Micro-Texturing onto the Copper SubstrateThe multi-head arrayed AISI316 punch was utilized for

micro-embossing onto a copper plate (20 mm × 10 mm).In this embossing process, the micro-textured punch wasincrementally loaded onto the copper substrate until thetotal load reached 20 kN. Each increment in strokes wasconstant by 25 μm.

Figure 9 depicts a typical micro-embossed copperplate. Two microgrooves (a’ and b’) correspond to two

Fig. 10. Micro-embossed copper substrate produced usingthe CNC-stamper.

Fig. 11. Comparison of the cross-sectional profile betweenthe micro-punch and the micro-embossed copper substrate.a) Convex surface profile of the micro-punch, and b) micro-embossed copper plate.

linear heads (a and b) in Fig. 7; next double-loop mi-crogrooves (c’ and d’) to c and d; triple-loop ones (e’,f’, and g’) to e, f, and g; and inner double-loop ones(h’ and k’) to h and k, respectively. That is, the multi-arrayed punch heads are embossed onto the copper sub-strate to form the micro-groove network. Fig. 10 showsthe micro-embossed copper substrate.

The micro-punch (Fig. 8) was embossed to form themicro-grooved copper substrate (Fig. 10). This micro-embossing behavior can be described by the compari-son of micro-textures between the micro-punch surface(Fig. 7) and the copper surface (Fig. 9). Fig. 11 com-pares the cross-sectional profiles between two and threecontinuous inner loop heads for the micro-punch in Fig. 7



Fig. 12. Plastic molded copper substrate as a package.

and their corresponding micro-groove network in Fig. 9,respectively.

Figure 11 a) depicts the cross-sectional surface profileacross the inner double loops (h and k) and triple loops(e, f, and g) on the surface of the micro-punch. Fivepunch heads have the same width and height of 70 μm and75 μm, respectively. Their width is broader than the orig-inal width of 50 μm (Fig. 4). The thickness of the plasma-printed parts in the AISI316 substrate by sand-blasting isequivalent to the depth of the nitrided layer thickness.

Figure 11 b) depicts the cross-sectional profile of themicro-embossed copper plate. Micro-grooves are formedby coining the micro-punch into the copper plate. In par-allel with this micro-embossing process, free volumes ofcopper plate are backward extruded into the open micro-cavities in the micro-punch. Their average depth reaches50 μm. Deeper micro-grooves can be formed in this cop-per substrate by incremental micro-embossing.

The convex punch heads correspond to the concavemicro-cavities in the copper substrate as shown in Fig. 11.This implies that the copper substrate is micro-embossedto have the tailored micro-grooving network in Fig. 4. Inaddition, the network with deeper grooves improves thejoinability by reducing the normal stress level.

3.4. Plastic MoldingEach of the twelve micro-textured copper plates were

joined by plastic molding to yield the packaged specimensfor gross leak testing. Fig. 12 depicts a typical plastic-mold package including the gold terminals.

The micro-grooving network in the copper substrate isfilled with thermoplastics that form the microtextured in-terface between the plastic mold and substrate.

3.5. Gross-Leak TestingAfter initial and preliminary testing (Table 1), no bub-

bles were detected in the twelve packaged specimens.This implies that this microtextured interface has suffi-cient integrity so as to be leak proof under normal condi-tions. In particular, the mechanical anchoring effect is en-hanced by the present micro-grooving network. The em-bedded mold part of the network is stiff, with high tensionand low compression and bending; these significantly re-duce the distortion of the interface. Further investigations

are required to prove the integrity of the specimens undersevere thermal cycles.

4. Discussions

The present CNC-stamping method in conjunction withthe plasma printed micro-punch is an automated ap-proach using micro-texture CAD for micro-embossingof the copper substrate. Via the finite element analysisin CAD, the optimized micro-texture geometry is trans-ferred onto the screen film. Two-dimensional alignmentof micro-texture is directly screen-printed onto AISI316die substrate as its negative pattern and is transformed intothree-dimensional nitrogen-embedded microstructure inAISI316 substrate via low temperature plasma nitriding.Through mechanical blasting, this microstructure changesinto three dimensionally arrayed micro-punch heads. Fi-nally, the initial CAD-data for micro-texture is transferredinto a three-dimensional micro-groove network on thecopper substrate for joining.

Little loss of accuracy in dimension and geometryoccurs during plasma printing from two-dimensionalscreen-printing to CNC micro-embossing of micro-texture into copper substrate. This automatic procedureneeds no preparation of computer aided manufacturing(CAM) data; the whole CAD data are once transferredinto a screen. The reproducibility of the micro-groovenetwork on the copper substrate is proved by the plasma-printed micro-punch. Although laser micro-texturingmethods are influenced by their thermal effect as well asirregularity in ablation, the geometric and dimensional re-liability of the micro-textures for joining is retained by theCNC-stamping capability as well as the AISI316 micro-die.

This automatic procedure also preserved the flexibil-ity of the micro-texture design toward the leak-free plas-tic packaging. Promotion of micro-joinability by the fi-nite element analysis reflects on the realignment of themicro-groove network on the copper substrate in the plas-tic package and results in improved leak-proof ability asdetermined by the gross leak testing.

The takt time required to produce the micro-texturedcopper substrate with the same grooves with the width of70 μm and depth of 50 μm (Fig. 10), differs during theprocesses of plasma printing and picosecond laser micro-texturing. In the present procedure, the screen-printing re-quires 5 min including setting-up and adjustment. Plasmanitriding needs 5 h (or 18 ks) including the setting-up,and the heating and cooling duration. The blasting re-quires 5 min (or 300 s). Hence, the total time is countedto be 18.6 ks to fabricate a micro-punch for simultane-ous production of 5×5 micro-textured copper substrates.CNC stamping needs 10 s at most for a single shot. As-suming that 1000 substrates are continuously producedduring an operation, takt time (τ) per textured substrateis estimated to be τ = (18600 + 40× 10)/1000 = 19 s.On the other hand, one operation to yield this optimallymicro-textured substrate by the picosecond laser micro-


Aizawa, T. et al.

texturing, requires at least 400 s, including the setting andadjustment but excluding the preparation of CAM data.

Considering that N substrates are continuously pro-duced by the present procedure, the takt time (τ(N)) persubstrate is given by τ(N) = 18000/N + 10/25. That is,this takt time converges to the ratio of the single stampingduration to the number of stamped substrates in a singleshot. Hence, the initial takt time for plasma printing be-comes negligibly small in mass production.

Mechanical joining with the aid of micro-textures tointegrate dissimilar materials into a unit or a cell with-out using chemical adhesive materials is essential to pro-duce the devices and sensors in addition to HEMT chips.The leak proof testing must be a guide to evaluate its in-tegrity in practice. In the present procedure, the samemicro-textured punch is used for CNC embossing processto produce the copper substrates shot-by-shot. Hence,the geometric accuracy of micro-textures during plasmaprinting and micro-embossing is responsible for the qual-ity assurance of products. Once the engineering tolerancein these two production steps is determined by proof test-ing, the quality of the integrated devices and sensors isautonomously ensured. This procedure is free from ther-mal disturbance as against laser micro-texturing as wellas from the limitations of chemical joining.

Tailoring optimum micro-textures for improved me-chanical joinability is considered by using three-dimensional finite element analysis in the present study.More rational approach to attain the uniform stress stateon the joined interface might be attained via topologicaloptimization [15].

5. Conclusions

Micro-texturing on the material interface of two dis-similar materials is essential to integrate the plastic pack-aged chips as well as micro-electro-mechanical system(MEMS) devices and sensors. Mechanical anchoringeffect on the joinability can be improved by optimiz-ing the three-dimensional micro-textures on the inter-face. Plasma printing has been developed as an au-tonomous procedure to transform two-dimensional CADdata to three-dimensional micro-punch array for micro-embossing. The micro-embossed copper substrates arejoined with the thermoplastic mold to package the hol-low HEMT-chip; the product is sufficiently leak proof.In addition to this, the takt time (τ(N)) to fabricate themicrotextured copper substrate is significantly reduced tothe ratio of single-shot stamping duration time (p) to thenumber (n) of substrates embossed in a single shot in caseof mass production for N � 1000. In the present exper-iment, τ(1000) is estimated to be 19 s for p = 10 s andn = 25. Considering that τ = 400 s to yield a single sub-strate by the picosecond laser micro-texturing, this shorttakt time by the present method has a positive impact onlarge-scale manufacturing.

Optimization of micro-textures plays an important rolein making the plastic packaging of hollowed chips highly

leak proof and promoting its interfacial strength. Topo-logical design is expected to be a rational approach in pre-dicting the optimum micro-grooving network in the cop-per substrate.

AcknowledgementsThe authors would like to express their gratitude to Ms. S.Hashimoto (TecDia, Co., Ltd.), Mr. Y. Yoshino (KSJ, Co., Ltd.),and Mr. S. Kurozumi (Nano-Coat-Film, LLC) for their help inmaterial characterization and stamping experiments, respectively.This study was financially supported in part by METI-program onthe supporting industries in 2018.

References:[1] A. Prejs, S. Wood, R. Pengelly, and W. Pribble, “Thermal analysis

and its application to high power GaN HEMT amplifiers,” Proc.IMS-2009, pp. 917-922, 2009.

[2] D. Doughetty, M. Mahalingam, V. Viswanathan, and M. Zimmer-man, “Multi-lead Organic Air-Cavity Package for High Power HighFrequency RFICs,” Proc. IMS-2009, pp. 473-476, 2009.

[3] A. Longford, J. Matlis, and J. Lynch, “Advanced of Using LCP-Based Pre-Molded Leadframe Packages for RF and MEMS Ap-plications,” Advancing Microelectronics, Vol.39, No.5, pp. 8-12,2012.

[4] A. Kobayashi, T. Hishinuma, and K. Satoh, “Microtexturing ofcopper substrates by nanosecond laser processing,” Japan Patent4020957, 2007.

[5] T. Aizawa and T. Inohara, “Pico- and femto-second laser microma-chining for surface texturing,” Z. Stanimirovic and I. Stanimirovic(Eds.), “Micromachining,” IntechOpen, 2019.

[6] Y. Saito, T. Aizawa, K. Wasa, and Y. Nogami, “Leak-proof packag-ing for GaN chip with controlled thermal spreading and transients,”Proc. BCICTS2018, pp. 243-246, 2019.

[7] T. Aizawa, “Plasma Printing: An Innovation Toward Micro- andNano-Manufacturing,” 3rd ISAST Conf. (Bali, Indonesia), CD-ROM, 2015.

[8] T. Aizawa, “Micro-manufacturing by controlled plasma technolo-gies,” Automobile Engineering, Vol.72, No.6, pp. 35-41, 2018.

[9] T. Aizawa and K. Wasa, “Plasma printing of micro-nozzles withcomplex shaped outlets into stainless steel sheets,” J. Micro Nano-Manuf., Vol.7, No.3, 034502, 2019.

[10] T. Aizawa and S. Yoshihara, “Microtexturing into AISI420 dies forfine piercing of micropatterns into metallic sheets,” J. JSTP, Vol.60,pp. 53-57, 2019.

[11] T. Shiratori, T. Aizawa, Y. Saito, and K. Wasa, “Plasma printing ofAISI316 multi-punch die micro-embossing into copper plates,” J.Metals, Vol.9, p. 396, 2019.

[12] Y. Saito, T. Aizawa, K. Wasa, and Y. Nogami, “Hollow packagingstructure, its manufacturing, semi-conductor chip utility system andits manufacturing,” Japan Patent 6625774, 2019.

[13] T. Aizawa, Y. Saitoh, and H. Hasegawa, “Leak-free plastic moldpackaging into micro-textured copper substrate by plasma printing,”Proc. 3rd WCMNM2019, TuAT3.1, 2019.

[14] T. Aizawa, T. Shiratori, and K. Wasa, “Plasma-printed AISI316Lmulti-punch array for fabrication of aluminum heatsink with micro-pillar fins,” Proc. 3rd WCMNM2019, WeBT1.2, 2019.

[15] http://www.quint.co.jp/ [Accessed June 27, 2019]



Name:Tatsuhiko Aizawa

Affiliation:Director, Surface Engineering Design Labora-tory

Address:3-15-10 Minami-rokugo, Ota, Tokyo 144-0045, JapanBrief Biographical History:1980- The University of Tokyo2005- University of Toronto2009- Shibaura Institute of TechnologyMain Works:• T. Aizawa, “Low temperature plasma nitriding of austenitic stainlesssteels,” Z. Duriagina (Ed.), “Stainless Steels and Alloys,” IntecOpen,pp. 31-50, 2018.• T. Aizawa, T. Yoshino, T. Shiratori, and S. Yoshihara, “Grain size effecton the nitrogen super-saturation process into AISI316 at 623 K,” ISIJ Int.,Vol.59, pp. 1886-1892, 2019.• T. Aizawa, T. Inohara, and K. Wasa, “Femtosecond lasermicro-/nano-texturing of stainless steels for surface property control,”Micromachines, Vol.10, 512-1-10, 2019.Membership in Academic Societies:• American Society of Mechanical Engineers (ASME)• Japan Society of Technology of Plasticity (JSTP)• Japan Society of Metals (JSM)

Name:Yasuo Saito

Affiliation:Director, Electronic Devices Division, ChuoDenshi Kogyo Co., Ltd.

Address:3400 Kooyama, Matsubase, Uki-city, Kumamoto 869-0512, JapanBrief Biographical History:1985- NEC Corporation2014- Chuo Denshi Kogyo Co., Ltd.Main Works:• Microwave amplifier design• Package design• Y. Saito, T. Aizawa, K. Wasa, and Y. Nogami, “Leak-proof packaging forGaN chip with controlled thermal spreading and transients,” Proc. of the2018 IEEE BiCMOS and Compound Semiconductor Integrated Circuitsand Technology Symp., San Diego, CA, USA, pp. 15-17, October 2019.

Name:Hideharu Hasegawa

Affiliation:Senior Manager, Development Department,Chuo Denshi Kogyo Co., Ltd.

Address:3400 Kooyama, Matsubase, Uki-city, Kumamoto 869-0512, JapanBrief Biographical History:1983- NEC Yamagata Co., Ltd.2010- Compound Semiconductor Device Division, NEC Electronics Co.,Ltd.2014- Chuo Denshi Kogyo Co., Ltd.

Name:Kenji Wasa

Affiliation:CEO, MicroTeX Labs Inc.

Address:The Johonan Shinkin Bank Hasunuma-branch 3F, 6-32-11 Nishi-kamata,Ota, Tokyo 144-0051, JapanBrief Biographical History:1976 Received B.E. in Electronics from Osaka University1978 Received M.E. in Electronics from Osaka University1981 Received D.E. in Electrical and Communications Engineering fromTohoku University1981- NEC Corporation2019- CEO, MicroTeX Labs Inc.Main Works:• Microwave devices and modules• Microfabrication of metals using plasma process


fabrication of optimally micro-textured copper substrates

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