The Investigation of Die Back Edge Cracking in Flip Chip Ceramic Ball Grid Array Package (FC-CBGA)

The cracking between die back edge and top fillet for Flip Chip Ceramic Ball Grid Array (FC-CBGA) package due to thermal cycling have been investigated in this study. Finite Element Analysis (FEA) model was used to analyze the effect of fillet geometry and material properties of underfill upon stresses along the die back edge. The thermo-mechanical properties of commercial underfill were obtained by using Thermal Mechanical Analyzer (TMA) and Dynamic Mechanical Analyzer (DMA) as the input for the simulation. Die stress distribution for different fillet height and width were generated to depict variation of stress due thermal loading and the variations of tensile stress were discussed for parameter optimization. The effect of different underfill material properties were discussed as well for thermal stress reliability improvement

Dimensional and structural stability of gamma irradiated stacked die quad flat no leads (QFN)

The physical properties and structural stability of the Quad Flat No-Leads (QFN) package with different gamma radiation doses have been investigated. The packages were irradiated with Co-60 gamma radiation with varying doses of 5 Gy, 50 Gy, 500 Gy, 5 kGy and 50 kGy with operating dose of 2.54 kGy/h at room temperature. The infinite focus microscope (IFM) was used to measure the dimensional change and slanting/warpage behaviour, while the 3D CT Scan X-ray machine was used to determine the occurrence of deflection on a wire in package due to exposure. It is believed that radiation effect on ceramic filler in the epoxy mold compound (EMC) plays an important role to induce the defects and resulted in swelling of the package. The slanting/warpage behaviour is believed to be caused by the swelling behaviour of ceramic filler and further induced structural stability. The induced stress on the EMC structural after the dimensional change and slanting/warpage failure leads to the occurrence of wire sweep. The finding suggests that defect production in swelled ceramic filler leads to the occurrence of dimensional and structure instability

Low temperature production of wollastonite from limestone and silica sand through solid-state reaction

AbstractWollastonite was produced using solid-state reaction from limestone and silica sand. Limestone containing a high percentage of CaO (55.10%) and silica sand with 99% SiO2 were used as starting materials. The ratios of limestone/sand used were 1:1, 2:1 and 3:1 with various firing temperatures, namely 1100, 1200, 1300, 1400 and 1450°C. The raw materials and fired products were characterised for mineral phases, chemical composition of content such as CaO, SiO2 and loss on ignition (LOI), density and microstructure. CaSiO3 with an α-phase was detected at firing temperatures as low as 1300°C, together with olivine and quartz phases, obtained from a 1:1 ratio. No α-CaSiO3 was detected for 2:1 and 3:1 ratios; only olivine and larnite phases were present. The density of the product was 2.93gcm−3, which is close to the theoretical value, with a specific surface area of 3.23m2g−1. This study shows that the Malaysian limestone and silica sand can produce good properties of wollastonite materials

Effect of high temperature corrosion on austenitic stainless steel grade 304 in CO2 gas at 700ºC

Austenitic stainless steels of grade 304 were exposed to dry (Ar-75%CO2) and wet (Ar-75%CO2-12%H2O) environments at 700oC. This experimental setup involved horizontal tube furnace connected to CO2 gas and water vapour facilities. X-ray diffraction (XRD) technique, variable pressure-scanning electron microscope (VP-SEM) and optical microscope techniques were used to characterize the products of corrosion. The results of XRD showed that the phase of oxide layers consists of Cr2O3 and NiCr2O4 in dry CO2, meanwhile Fe2O3, Cr2O3, Fe0.56Ni0.34, Fe3O4 were identified in wet condition after 50 h. Adding 12%H2O in Ar-75%CO2 leads significantly in weight change occurred at 10 h exposure. However, after 20 h, the weight gain was decreased due to spallation of the oxide scale. The addition of water vapour accelerates the oxidation rate on the steel than that in dry condition. Morphologies and growth kinetics of these oxides vary with reaction condition. The oxidation behaviour at different times of exposure and the effect of water vapour were discussed in correlation with the microstructure of the oxides

Kelakuan migrasi elektrokimia pateri SAC305 dalam larutan natrium hidroksida pada kepekatan yang pelbagai

Pengecilan saiz antarahubung dalam papan litar bercetak (PCB) membawa kepada migrasi elektrokimia (ECM) dan kemudiannya menyebabkan litar pintas. ECM merupakan salah satu jenis kakisan yang ketara menjejaskan kebolehtahanan kakisan kepada peralatan elektronik. Migrasi ini ialah fenomena ion logam bergerak dari satu kawasan ke kawasan yang lain di dalam medium logam, menyebabkan endapan berlaku di bahagian katod logam ataupun aloi. Justeru, kajian ini dijalankan untuk menentukan kelakuan kakisan melalui ujian titisan air (WDT) pateri bebas plumbum Sn-3.0Ag-0.5Cu (SAC305) di dalam larutan natrium hidroksida (NaOH) yang berbeza kepekatan iaitu 0.05M, 0.1M, 0.5M dan 1.0M. Purata masa-ke-kegagalan (MTTF) pateri SAC305 berkurangan apabila didedahkan kepada medium larutan NaOH yang semakin tinggi kepekatannya. Pembentukan dendrit dikesan selepas kakisan pateri SAC305 akibat proses ECM dan menyebabkan litar pintas. Hasil kakisan Cu(OH)2 dan SnO2 juga didapati terbentuk selepas pateri terkakis. Bopeng kecil kelihatan terbentuk terutamanya pada kepekatan yang tinggi adalah disebabkan oleh perlarutan pada anod Sn

Kesan kemasan permukaan berbeza terhadap sifat mikromekanik sambungan pateri Sac 0307 menggunakan pendekatan pelekukan nano

Sifat fizik dan mekanik sambungan pateri pada papan litar bercetak (PCB) sangat bergantung kepada bahan pateri dan permukaan penglogaman PCB. Kemajuan penyelidikan dan pembangunan bahan pateri bebas plumbum membuka peluang untuk menghasilkan sambungan pateri yang mempunyai kebolehtahanan yang tinggi. PCB/Cu merupakan PCB tanpa kemasan digunakan sebagai sampel kawalan manakala dua PCB yang lain iaitu PCB/ImSn (immersion tin) dan PCB/ENiG (electroless nickel immersion gold) dipilih untuk mengkaji kestabilan sambungan pateri. Sambungan pateri pada kemasan permukaan yang berbeza didedahkan kepada penyimpanan suhu tinggi (HTS) pada suhu 175°C selama 1000 jam untuk mengkaji perubahan sifat mikromekanik. Ujian pelekukan nano memberikan sifat mikromekanik yang bersifat setempat. Perubahan kekerasan antarasambungan SAC 0307 selepas HTS ialah 66 MPa bagi PCB/Cu, 107 MPa bagi PCB/ImSn dan 45 MPa bagi PCB/ENiG. Analisis terhadap sifat mikromekanik mendapati bahawa PCB/ENiG menunjukkan perubahan nilai yang minimum berbanding dengan PCB/Cu dan PCB/ImSn. Ini menunjukkan PCB/ENiG memberikan kestabilan sifat mikromekanik yang tinggi selepas didedahkan pada HTS pada suhu 175°C selama 1000 jam

Penilaian semula pengukuran kuantitatif stereometri terhadap pertumbuhan sebatian antara logam bagi sambungan pateri

Pencerapan dua dimensi (2D) yang diperoleh daripada keratan rentas sampel selalunya digunakan untuk mendapatkan maklumat ketebalan lapisan sebatian antara logam (IMC). Walau bagaimanapun, pencerapan 2D amatlah terhad berbanding maklumat yang sepatutnya diperoleh daripada struktur tiga dimensi (3D) sampel. Kajian ini bertujuan untuk menilai semula kaedah pengukuran lapisan IMC daripada pemerhatian 2D dengan mempertimbangkan faktor-faktor sebenar dalam bentuk 3D IMC. Nilai mod ketebalan didapati lebih mewakili nilai ketebalan IMC setelah mempertimbangkan pelbagai faktor stereometri berbanding dengan nilai purata. Ini memberikan suatu penanda aras dalam aktiviti menentukan ketebalan lapisan IMC berdasarkan pencerapan 2D daripada struktur 3D

Structural Assessment of Lead Free Solder Joint of Miniaturized Electronics Assembly

This paper presents a study on structural assessment of ultra-fine package assembly with nano-composites lead free solder joint after reflow soldering process. In this work, various nanoparticles (i.e. TiO2, Fe2O3 and NiO) with different weightage percentage (i.e., 0.01, 0.05 and 0.15 wt.%) were successfully incorporated into SAC305 solder paste using the mechanical solder paste mixer to synthesize novel lead-free composite solders. Effects of the nanoparticles addition on the quality of joining and fillet height between various weightage (wt.%) for the ultra-fine package assembly in the reflow soldering process have been investigated after the reflow soldering process by using the scanning electron microscope (SEM) system equipped with an energy dispersive X-ray spectroscopy (EDS) and XTV 160 x-ray inspection system. The experimental results show the increment of TiO2, Fe2O3 and NiO nanoparticles addition to 0.15wt.%, 0.05wt.% and 0.01wt.%, respectively, produce highest fillet height of each composition of nanoparticles solder paste. Among all these new composition of nanoparticles solder paste, NiO nanoparticles reinforced solder paste with 0.01wt.% yielded highest fillet height The miniaturized solder joints do not cause any problem in terms of solder voids. The findings show the capability of the reflow soldering process in assembling miniaturized electronics assembly and expected to provide a reference in electronic package industry

Kesan teknik pengaktifan bermangkin berbeza terhadap prestasi terma penyebar haba cip balikan(Effects of different catalytic activation techniques on the thermal performance of flip chip heat spreader)

Kertas ini membentangkan kesan dua teknik pengaktifan bermangkin yang berbeza terhadap prestasi terma bagi penyebar haba cip balikan. Penyaduran nikel tanpa elektrik digunakan sebagai salah satu teknik saduran kerana ia boleh membentuk satu lapisan nikel yang ketebalannya seragam ke atas substrat kuprum. Proses pengaktifan bermangkin perlu dilakukan dahulu untuk mengenapkan sesetengah atom nikel ke atas substrat kuprum, supaya enapan nikel mampu untuk memangkinkan proses penurunan yang seterusnya. Dua jenis teknik pengakitfan telah dikaji, iaitu pemulaan galvani dan penyaduran nipis nikel-kuprum. Ujian simpanan suhu tinggi telah dijalankan untuk mengkaji takat resapan antara logam bagi lapisan nikel and kuprum. Kemeresapan terma bagi penyebar haba telah dikaji dengan menggunakan peralatan Nano-flash. Keputusan yang diperolehi menunjukkan bahawa penyebar haba yang diproses dengan penyaduran nipis nikel-kuprum mempunyai nilai kemeresapan terma (35-65 mm2 s-1) yang lebih rendah berbanding dengan penyebar haba yang diproses dengan teknik pemulaan galvani (60-85 mm2 s-1). Selain daripada itu, kajian ini juga menemui ketebalan lapisan antara logam nikel-kuprum dalam penyebar haba ini bertambah daripada 0.2 μm pada keadaan asal kepada 0.55 μm selepas 168 jam simpanan suhu tinggi. Lapisan antara logam nikel-kuprum mempunyai kekonduksian terma yang lebih rendah berbanding dengan kuprum tulen, ini telah merendahkan kemeresapan terma bagi penyebar haba. Kesimpulannya, teknik pemulaan galvani meyediakan prestasi terma yang lebih baik untuk penyebar haba yang digunakan dalam pembungkusan semikonduktor

The effect of magnetic field on copper in various corrosive medium

The effect of applied magnetic field on the corrosion behaviour of copper within various corrosive medium is investigated. The copper coupon is immersed in 0.5 M HCl, 0.5 M NaCl and 0.5 M NaOH with or without applying up to 40 mT magnetic fields for 24 hours. The weight loss of copper coupon in HCl increased up to 96.56% with applied magnetic fields. However, in NaOH medium, only 33.33% more weight loss was observed and no difference were observed for coupons in NaCl when magnetic field is applied. This observation indicates that corrosion behaviour in HCl and NaOH is controlled by mass transport that can be influenced by the induced magneto hydrodynamics effect when magnetic field is applied. There was no change in weight loss of copper in NaCl when magnetic field is applied because the corrosion mechanism of copper in NaCl is governed by electron charge transfer