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An accelerated reliability testing via thermal cycling test (TCT) was used to test ball grid array (BGA) components’ reliability. Five variables were observed; control sample J and samples K, L, M, and N were BGA component samples that have been exposed to TCT between 500 and 1250 cycles with the TCT profile in the range of 0 °C–100 °C. The crack orientation of the individual solder joint was analyzed along with the propagation path pattern on the solder array of the BGA component pad by analyzing the dye and pull test results that were then mapped and analyzed using the cardinal and ordinal directions approach. This is to determine the crack propagation path direction in the solder array and track the potential of warpage on the BGA package as the TCT cycles progressed. A cross section was performed on sample M with the 3-D X-ray and scanning electron microscopy (SEM) analysis to observe the solder joints’ fracture lines and surface topographies. The results showed that individual solder joint crack orientation is correlated to the crack propagation location on the BGA package. The solder joint from northwest (NW), northeast (NE), southeast (SE), and southwest (SW) of the BGA package is prone to solder crack compared to the solder joint array in the middle. A solder grain structure coarsening occurred at the crack propagation due to the high cyclic strain from the TCT. [ABSTRACT FROM AUTHOR]

Methanesulfonic acid (MSA) has been widely used in the electroplating step at a backend semiconductor assembly process. This process comes after component encapsulation, which serves primarily to protect internal components of a device as well as to prevent ingression of chemical byproducts. The objective of this article is to study sulfur (S) ingression activities with respect to both electroplating and encapsulation processes and their effect on leadframe surface conditions. This can be achieved through observation of leadframe surface condition on samples prepared through laser ablation or mechanical decapsulation. Results from 17 engineering lots show that 25% of samples analyzed were observed with leadframe surface irregularities. The energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the trace of S element on the area with surface irregularities, which can be linked to S ingression based on the trace of its path from outside, probably due to the existence of a microgap on the package. These findings provide a clearer understanding of the ingression path of S for encapsulated copper (Cu) leadframe. Even though ingression of S does not directly cause a failure, it is thought that this could act as a precursor to further failure mechanisms such as corrosion-like phenomena. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate 2-methoxyethanol-sensitive ZnO nanorods based on electrolyte–insulator–semiconductor (EIS) structure. The hydrothermal method is employed to synthesize the ZnO nanorods on Si substrate. The structural, morphological, compositional, and optical features of ZnO nanorods are analyzed, confirming the formation of hexagonal structure in ZnO nanorods. We investigate the sensing performance of EIS-based ZnO nanorods for the detection of various organic solvents (2-methoxyethanol, ethanol, and methanol) at various concentrations. As a chemical sensor, these EIS-based ZnO nanorods are capable of generating a different exposure response to 2-methoxyethanol than to methanol than to ethanol. The highest sensitivity, stability, and reproducibility are with respect to 2-methoxyethanol, making the ZnO nanorods prepared here a promising sensing membrane for 2-methoxyethanol. [ABSTRACT FROM AUTHOR]

The evaluation of the manufacturability, bondability, and reliability performances of the granular capillary is required to produce high-quality wire bonds. In this paper, two different types of wire bonding capillaries, namely, granular and conventional capillaries, were used for the gold (Au) wire bonding process. The wire pulling test was performed on the Au wire bonds created by both types of capillaries right after the wire bonding process and after the Au wire bonds were gone through accelerated tests of high-temperature storage and temperature cycling tests. It is noted that wire pull strengths were increased with the usage of the granular capillary compared to that of the conventional capillary for all five samples due to the occurrence of intimate bond between Au wedge bonds and bond pads. The increase of yield and the occurrence of consistence with one type of the failure mode for the Au wedge bonds that used granular capillary are due to the increment of scrubbing surface area between Au wire bonds and bond pads. The reduction of wire bonder stoppage with the usage of the granular capillary is due to the reduction of the short tail failure mode occurrence. This can be seen through the increment of the average yield percentage. It is observed that the granular capillary has the highest number of touchdowns or lifetimes compared to that of the conventional capillary. It is also found that the created wire bonds that used granular capillary have good bondability and reliability. These findings are based on the evaluation of the bonding interface thickness and distribution. [ABSTRACT FROM AUTHOR]

We report on the effect of the aspect ratio of zinc oxide (ZnO) nanorods (NRs) prepared by the hydrothermal process. It was found that increasing the precursor molar amount resulted in the decrease of the aspect ratio of ZnO NRs. Furthermore, the aspect ratios showed a significant effect on the structural and optical properties of the prepared ZnO NRs. The ZnO NRs were fabricated into a metal–semiconductor–metal (MSM) UV photodetector. The performances of the prepared MSM ZnO NRs were also studied, and the high aspect ratio showed that the highest responsivity had a value of 33 A/W at a bias voltage of 5 V and a wavelength of 380 nm. The responsivity, rise time, and full time of the prepared ZnO NRs showed a trend of behavior as the molar amount of the precursor was varied. [ABSTRACT FROM PUBLISHER]

Several types of metallization have been used in order to enhance the bondability of wire bond. The introduction of copper (Cu) wire bond further increases the requirement of finding the suitable metallization. In this paper, two types of metallization, namely silver (Ag) and nickel-palladium–gold-silver (Ni/Pd/Au/Ag), deposited on Cu substrate were used as the bond pad for the second Cu wire bond. Wire pulling test was conducted on the Cu second bond by placing the hook near the second bond in order to obtain consistence stich of Cu wire bond. The characteristic remaining area of stich was obtained using the image processing software Image J. It was observed that the pull strength of the Cu second bond was higher for Ag metallization compared with that of Ni/Pd/Au/Ag metallization. It was also shown that the Cu second bond on the Ag metallization has higher contact diameter compared with that of Ni/Pd/Au/Ag metallization. The contact diameter of the Cu second bond on Ag metallization has higher value and it can be correlated with its higher value of pull strength. The characteristic area was found to be proportionally related with the pull strength of second bond. [ABSTRACT FROM PUBLISHER]