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150 ㎛ 높이 구리기둥 적용 패키지-온-패키지 적층 접합 특성
김미송,현소희,배주영,홍원식 대한용접접합학회 2024 대한용접·접합학회지 Vol.42 No.4
In this study, we used copper (Cu) posts, plated to a height of 150 μm, as interconnections to form electrodes between different package layers. The upper layer consisted of a chip-scale package (CSP), while the lower layer was made up of a flip chip-chip scale package (FCCSP). We plated a Cu post on the side of FCCSP substrate, and produced the FCCSP package by thermo-compression (TC) bonding with copper pillar solder bumps on the center of substrate. The surface of the bottom electrode for the upper CSP received a surface finish of electroless nickel, electroless palladium, and immersion gold (ENEPIG). The bonding surface of the lower FCCSP was the bare Cu surface of the epoxy-molded Cu post. The PoP joining process used a vacuum reflow process with solder paste and solder balls. To understand the package joint's characteristics, we measured voids and shear strength, and analyzed the cross-sectional microstructure. The temperature profile used in the PoP joining process demonstrated optimal joint characteristics with a joint void content of 2.3% and a joint strength of approximately 44 MPa when formic acid was utilized and the activation preheating time was extended. Cross-sectional warpage analysis of the PoP package revealed a minimal difference of approximately 31 μm between the center and the ends. This study successfully developed a stacked package with a PoP structure using Cu Post, and the bonding process was optimized to minimize warpage in the PoP package.
이예림,소희진,장윤환,조수연,백대현,임경아,현정원,한규섭,강혜진 대한수혈학회 2011 大韓輸血學會誌 Vol.22 No.1
There have been 5 case reports about immune hemolytic anemia related with cimetidine, but there has been no such report in Korea. A sixty-four-year-old woman was admitted to the emergency department in a coma. She was diagnosed with diffuse large B-cell lymphoma 5 years ago and she achieved a complete remission after treatment. She was in a state of shock, and her blood pressure was 70/40 mmHg. The laboratory test results were consistent with hemolytic anemia (HA) as follows: hemoglobin: 1.9 g/dL, corrected reticulocyte count: 2%, total/conjugated bilirubin: 6.4/2.1 mg/dL, lactate dehydrogenase: 1,083 U/L and haptoglobin <10mg/dL. She had a history of taking the drugs including cimetidine, acetaminophen and etizolam for two days. She urgently received transfusion of 3 units of packed red blood cells and then she regained consciousness. To investigate the relation between cimetidine and HA, we subsequently performed a drug-induced immune complex test and an antibody test by using cimetidine, AB serum and phosphate-buffered saline. The results proved that cimetidine was the cause of the HA. Patient was treated with steroid, and the following laboratory tests showed rapid improvement. This is the first case report from Korea that shows the causal relationship between cimetidine and immune HA.
Sn-3.0Ag-0.5Cu와 Sn-0.75Cu(-Ni,Bi) 솔더볼 합금조성에 따른 Heterogeneous BGA 솔더 접합부 열사이클 특성
배주영,김미송,현소희,이종현,문정탁,이영우,이슬기,김형태,백승관,홍원식 대한용접접합학회 2024 대한용접·접합학회지 Vol.42 No.2
Sn-3.0Ag-0.5Cu (SAC305) is one of the most commonly used Pb-free solder composition nowadays. A minor alloying element addition can improve mechanical properties and thermal reliability of the solder joint. Minor amount of Bithmuth (Bi) or Nickel (Ni) addition can improve mechanical properties of solder by solid solution strengthening, or ensure the structural stability of the intermetalllic compounds. Also, low melting temperature solder with Bithmuth can reduce the cost of soldering process and keep components from deterioration. In this study, reliability of heterogeneous and homogeneous solder joint in the ball-grid-array (BGA) package solder joint were investigated. Using Sn-3.0Ag-0.5Cu (SAC305) solder paste and two kinds of solder balls, we have investigated which combination of solder joint improves the thermo-mechanical reliability. SAC305 and SCN (Sn-0.75Cu-Ni,Bi) balls were used for homogeneous and hetrogeneous joints. Solder balls were attached in BGA package. To examine the solder joint reliability, thermal cycling test was conducted after reflow soldering. Shear strength measurement and cross-sectional analysis of the BGA package solder joints were carried out before and after 2000 cycles of the test. The shear strength of homogeneous solder joint decreased to 68.2% and heterogeneous decreased to 43.5%. The crosssectional analysis using scanning electorn microscopy (SEM) and electorn back-scattered diffraction (EBSD) showed the (Ni,Cu)6Sn5 and Cu6Sn5 IMCs which were generated in the solder joint, and the crack propagated longer in the homogeneous solder joint of SAC305 after the thermal cycling test. IPFM showed the grain refinement effect of the SCN solder joint after thermal cycling. The minor addition of Bi had played a role as dislocation pinning site and became to equiaxied grain, so that the lifetime of heterogeneous SCN solder joint was superior than that of the SAC305.