Effects of Plasma Treatment on the Peel Strength of Ni on Polyimide

우태규,박일송,Kwang-Hee Jung,Woo-Yong Jeon,Young-Kyu Hwang,설경원 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.2

In microelectronics packaging, the reliability of the metal/polymer interface is an important issue because the adhesion strength between dissimilar materials is often inherently poor. This paper reports the peel strength and surface morphology of a Cu/Ni/PI structure flexible copper clad laminate (FCCL) based on polyimide(PI)according to the pre-treatment atmosphere and times. Field emission scanning electron microscopy (FESEM),x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) were used to analyze the surface mor-phology, crystal structure and interface binding structure, respectively, of the sputtered Ni, Cu, and elec-trodeposited copper foil layers. The surface roughness of the Ni and Cu sputtered deposition layers and the crystal structure of the electrodeposited Cu layer changed according to the pre-treatment atmosphere and times of PI. The PI surface etching speeds and surface shapes differed according to the gas used in plasma preprocessing. The highest peel strength (mean 15.8 gf/mm) can be obtained in a preprocessing process for 400 seconds in an O2 atmosphere due to the increase in mechanical binding force and change in chemical binding structure caused by the increase in polyimide surface roughness.

The Effect of Additives and Current Density on Mechanical Properties of Cathode Metal for Secondary Battery

우태규,박일송,설경원 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.4

Electrolyte copper foils used as a cathode material in secondary cells require the mechanical characteristic of high elongation ratios. In this study the effects of additives, current densities, and concentrations of sulfuric acid used in electrolyte plating on the mechanical characteristics of copper foils are analyzed. In the case of additive A, no significant changes in tensile strength and crystal structure were observed, but the elongation ratio is reduced by 43% when 100 ppm of additive is added. For additive B, the elongation ratio is rapidly decreased even though the growing orientation of crystals becomes parallel to the faces of (111) and (220)from the face of (200). In the case of decreasing current densities or increasing concentrations of sulfuric acid, the elongation ratio is respectively increased by 74% and 54%, and the growing orientation of crystals is directed from (200) to (111). Also, for additive A at low current densities, the increase in crystal sizes differed from that of high current densities. This approach represents a possible method for additionally improving elongation ratios by properly controlling the amount of the additive A.

고전류밀도에서의 첨가제 초기 거동 및 동박의 기계적 특성

우태규,박종재,박일송 대한금속·재료학회 2021 대한금속·재료학회지 Vol.59 No.5

In this study, we studied the surface and mechanical properties of multiple additives as well as the initial plating properties of individual additives. With the individual additive groups, copper crystals tended to converge at a stage above the critical amount of additive. When chloride ions were added, large crystals formed at several places on the surface. Thereafter, small crystals were attached to and grew on the surface of the large crystals. When collagen and JGB (Janes Green B) were added individually, the crystals were more uniformly distributed on the surface as compared with the group with added chloride ions. In addition, starlike crystals were grown depending on the amount of addition. It was necessary to use multiple additives, which is why it is difficult to make a uniform surface layer with individual additives. Large crystals of more than 10 μm formed unevenly on the surface treated with multiple additives of chloride ions and MPSA (3-mercapto-1-propane sulfonic acid). Large crystals disappeared on the surface treated with additional collagen along with multiple additives. However, valley like shapes were observed on this surface, due to the large crystals. But, addition of JGB additives to this reduced the valley and formed a uniform plating layer. MPSA and 20 ppm of collagen were added as multiple additives, grain sizes increased by 93.5% (220 peak) and 172.3% (311 peak) compared with the non-additive group. As a result, tensile strength decreased by 24.5% and elongation increased by 17.8%. The crystal size was reduced 25.0% on average by the addition of 10 ppm JGB, which contributed to a 5.4% increase in tensile strength and a 16.0% decrease in elongation. The grain size and surface properties could be controlled by adding multiple combinations of additives. As a result, It was confirmed that mechanical properties could be controlled by the proper amount and the optimum combination of additives.

JGB 첨가제에 의한 동박의 미세구조변화와 전기적 특성

우태규,박일송 대한금속·재료학회 2021 대한금속·재료학회지 Vol.59 No.6

Extremely thin film high quality copper foil is required to ensure high performance in electronics and slimness in secondary batteries. During the electroplating of copper foil, Janus Green B(JGB) and Collagen were introduced as additives to the electrolytes to study their effects. The structural and electrical properties of the electroplated copper foil were evaluated. When each additive was added individually, the potential was increased. Specifically, the potential of the group with 30 ppm added collagen was about 27% higher rather than the non-additive group. When Cl- ions and MPSA(3-mercapto-1-propane sulfonic acid) were added to the electrolytes without collagen and JGB, the surface roughness(Rz) increased by about 136% to 2.24 μm compared to the non-additive group. This was the highest value among all groups. However, a uniform layer with a surface roughness value below 0.3 μm was formed when less than 30 ppm and 10 ppm collagen and JGB were added, respectively, to the electrolyte. The direction of crystal growth with the JGB additives tended to go forward to the (220) direction, and the crystal size was reduced by 10~27% compared to the non-additive group. The addition of Collagen is necessary to reduce the difference in resistivity of the shiny layer and right matte layer. JGB additives were required to reduce the deviation in grain size. The results confirmed that the accelerators, inhibitors and leveler need to be properly added to form a copper plating layer with low surface roughness and to reduce differences in crystal texture of the shiny layer and right matte layer. Copper foil can be safely and uniformly deposited from electrolytes with JGB below 10 ppm and collagen below 30 ppm.

Effect of RF Sputtering Power on the adhesion of Ni thin film to polyimide

우태규,박일송,Kwang-Hee Jung,전우용,설경원 대한금속·재료학회 2011 ELECTRONIC MATERIALS LETTERS Vol.7 No.4

This study represents the results of an investigation of the peel strength and surface morphology according to the Ni sputtering power in producing Cu/Ni/PI structured flexible copper clad laminate (FCCL) using polyimide (PI). In order to analyze the surface morphologies of the sputtered Ni, Cu, and electrodeposited copper foil, and their crystal structure and interface binding structure, field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used. The surface roughness of the deposited layers and the crystal structure of the electrodeposited Cu layers varied according to the Ni sputtering power. In the range of RF output of 100~400 W in the Ni deposition process, the metal layers deposited at a power of about 300 W showed a homogeneous surface morphology and also exhibited a high peel strength for polyimide. The peeling that occurred at the interface of NiPI in the specimen fabricated using an Ni sputtering power of 300 W was due to the fact that the peeling usually occurs inside the polyimide. In the results of the XPS analysis on the separated Ni surface, the peaks of C and N, which are the major elements in polyimide, showed higher levels compared to those observed under the other conditions.

구리 전해도금 시 표면형상과 기계적 특성에 미치는 HEC효과

우태규,박일송,이현우,설경원,Woo, Tae-Gyu,Park, Il-Song,Lee, Hyun-Woo,Seol, Kyeong-Won 한국재료학회 2006 한국재료학회지 Vol.16 No.11

The purpose of this study is to identify the effect of additives and composition on copper surface morphology and mechanical characteristics by copper electrodeposition. Additives such as hydroxy ethyl cellulose(HEC), chloride ion were used in this study. Electrochemical experiments allied to SEM, XRD, AFM and four- point probe were performed to characterize the morphology and mechanical characters of copper in the presence of additives. Among various electrodeposition conditions, the minimum surface roughness of copper foil was obtained when electrodeposited at the current density of 200 mA/$cm^2$ for 68 seconds with 2 ppm of HEC. The minimum value of surface roughness(Rms) was 107.6 nm. It is copper foil is good for electromigration inhibition due to preferential crystal growth of Cu (111) deposited in the electrolyte containing chloride ions(10 ppm) and HEC(1 ppm).

고전류밀도에서의 Benzothiazole 첨가제의 동박 특성에 미치는 영향

우태규,강병재,박종재,박일송 한국표면공학회 2022 한국표면공학회지 Vol.55 No.4

The electroplating for copper foils has many advantages in economics. During the electroplating, the selection of appropriate additives is needed to manufacture copper foils with various properties. Therefore, it is investigated the initial plating voltage and the properties of copper foil electroplated in the electrolyte with benzothiazole as additives. The addition of benzothiazole without any additives decreased effectively the initial plating voltage. However, the initial voltage increased when the additives was used in combination with an inhibitor and a leveler along with benzothiazole. Moreover, the voltage tends to increase with the concentration of benzothiazole except for 40 ppm group. The mixed additives could change not only the initial voltage but also the morphology of crystals on the surface. When benzothiazole is added at 20 ppm or less, it was observed that the clustered crystals existed on the surface, which result in ununiform surface and high roughness value. In addition, the grain size increased with the amount of benzothiazole, but the resistivity decreased. However, when the leveler was added in 20 ppm, the grain size was decreased with the amount of benzothiazole. The size of the crystals could be influenced by the mixing ratio of additives. Therefore, it is necessary to study on the effect of concentration ratio of additives in the future.

고전류밀도에서의 탄산칼륨 첨가제의 전해동박 특성에 미치는 영향

우태규,박일송 대한금속·재료학회 2023 대한금속·재료학회지 Vol.61 No.5

The amount and kind of additives in electrolytes play a very important role on the electroplatingof Cu foil, which is used as a cathode materials for secondary batteries. As the use of Cu foil increased, variousstudies on the electroplated Cu foil are urgently needed. We studied surface characteristics and changes instructural properties due to the addition of inhibitors under electroplating conditions with high currentdensity. The surface layer was observed, to analyze the effect of the amount of potassium carbonate as aninhibitor. When the potassium carbonate was added at 5~25 ppm without any other additives, the initialplating voltage was observed to decrease. To uniformly distribute crystals without agglomeration at the initialstage of electroplating, it is reasonable to add potassium carbonate within the range of 20~25 ppm. There wasno significant difference in surface roughness and specific resistance due to the amount of potassiumcarbonate, when the additives were added complexly. There was an increase in the relative strength of thepreferred growth orientation of (220) in a group with 20 ppm potassium carbonate, compared to the groupwith 10 ppm potassium carbonate. The grain size decreased with the amount of potassium carbonate addedwith other additives. However, there was no significant difference in tensile strength and elongation (p-value:0.000). To ensure uniform properties with a combination of 4 kinds of additives it is reasonable to addpotassium carbonate in the range of 10~20 ppm.

고전류밀도에서 유기첨가제에 의한 구리 전착층의 전기적 특성 변화

우태규,박일송 대한금속·재료학회 2020 대한금속·재료학회지 Vol.58 No.1

Electroplating has many economic advantages in producing copper foils. The easiest way to manufacture electroplated copper foil with various properties is to add appropriate additives. This study evaluated the surface properties, mechanical and electrical properties of copper foil electroplated in electrolytes containing the leveler JGB (Janus Green B). When the leveler JGB was added as an additive, Cu crystals were distributed uniformly on the surface layer in an initial nucleation process. In the JGB-free group, dents and pinholes were observed on the surface of the electroplated Cu foil. Such surface defects were reduced with the addition of JGB. Surface roughness was decreased by 68% in the samples electroplated in electrolytes with 10 ~ 40 ppm JGB, when it is compared with a JGB-free sample. It was observed that the priority growth direction of crystal texture changed from (200), (111) to (220). Elongation decreased by 59%, while the tensile strength increased by 157% due to a decrease in crystal size by 69%. With the addition of 0 ~ 40 ppm JGB, resistivity increased due to the decrease in crystal size and changes in the crystal texture. Based on a linear regression approximation between 0 and 40 ppm the value of R2 was 91.4%. There was no statistically significant difference between 40 and 60 ppm, and the resistivity was 37.7% higher than in the JGB-free sample.

젤라틴 및 염소이온 첨가에 의한 구리 박막의 미세조직 및 기계적 특성 고찰

우태규,이만형,설경원 대한금속·재료학회 2018 대한금속·재료학회지 Vol.56 No.7

This study investigated the crystal structure and mechanical properties of copper foil electroplated by adjusting gelatin and chloride ions from 0 to 100 ppm. There was increased formation of spherical crystals and surface roughness on the surface of the electroplated layer when the gelatin was added, and the direction of crystal growth was parallel to the (111) plane. The grain size of the copper foil electroplated in the electrolyte containing 30~60 ppm of gelatin was smaller than that of groups with no additive. As a result, hardness increased, but elongation decreased. In contrast, the elongation and the crystal size of copper foil formed in the electrolyte containing chlorine ions increased more than the group with no additive. The clearly observed tendency was that crystals of the group with no additive as well as the group with added chloride ions grew along the (220) plane. However, the use of the electrolyte with chlorine ions and gelatin additives was not enough to obtain a uniform surface and desirable mechanical properties in the electroplated layer. The addition of a leveler and brightener could be used to fabricate useful copper foil. The tensile strength was similar for the no additive group and mixed additive group. However, it was observed that the grain size of the mixed additive group elongated 34.1% more than the no additive group.