Jungsik Park

Adhesion improvement of epoxy resin/copper lead frame j oints by azole compounds

The adhesion strength of epoxy resin/copper joints is often very poor, due to the naturally formed copper oxide having a low mechanical strength. To improve the adhesion strength of epoxy resin/copper lead frame joints, copper lead frames were treated with azole compounds as adhesion promoters. The azole compounds used were benzotriazole (BTA), benzotriazole-5-carboxylic acid (CBTA), 8-azaadenine, imidazole, 2-methyl imidazole, urocanic acid, adenine, benzimidazole, and polybenzimidazole (PBI). The dependence of the adhesion strength of epoxy resin/azole-treated copper joints on the structure of the azole compound, the azole treatment time, and the azole treatment temperature was investigated. The surface coverage of azole-treated copper was examined by contact angle measurements, a surface defect test, optical microscopy, and scanning electron microscopy (SEM), and the locus of failure was studied by X-ray photoelectron spectroscopy (XPS). Triazole compounds such as CBTA and 8-azaadenine showed excellent...

Study of a T-Shaped Slot With a Capacitor for High Isolation Between MIMO Antennas

In this letter, an isolation improvement method between two closely packed planar inverted-F antennas (PIFAs) is proposed via a miniaturized ground slot with a chip capacitor. The proposed T-shaped ground slot acts as a notch filter, and the capacitor is utilized to reduce the slot length. The equivalent circuit model of the proposed slot with the capacitor is derived. The measured isolation between two PIFAs is down to below -20 dB at the whole WLAN band of 2.4 GHz.

Adhesion improvement of epoxy resin to alloy 42 lead frame by silane coupling agents

Three different silane coupling agents were used to improve the adhesion between epoxy resin and alloy 42 lead frame. The adhesion strength and durability of epoxy resin/silane coupling agent-treated alloy 42 joints were investigated. The highest initial adhesion strength, 200 N/m, was obtained with γ-aminopropyltriethoxysilane (y-APS), but durability in a high humidity environment was best with N-,β-(aminoethyl)-y-aminopropyltrimethoxysilane (AAMS). An optimum concentration of the silane coupling agent was determined and thermal stability was studied by thermogravimetric analysis (TGA). Vapor phase deposition of the AAMS silane coupling agent was also employed and compared with dipping of the lead frame in the silane coupling agent solution. Moisture absorption behavior was examined for different silane coupling agents and for different geometries of the joints to resolve the moisture absorption path of joints. The improvement in adhesion obtained by applying a silane coupling agent to the lead frame can...

Small GPS antenna with lumped elements and interdigital structure

In this paper, a miniaturized global positioning system (GPS) antenna embedded in a printed circuit board (PCB) is presented. The proposed antenna employs lumped elements and an interdigital structure to reduce an operating frequency and to achieve good input matching. Furthermore, the system ground plane is included to work out a radiator. The size of the proposed antenna is 8 mm × 4.5 mm. The bandwidth under VSWR of 2:1 is 20 MHz from 1561 MHz to 1581 MHz. The measured antenna gain and the efficiency are 1 dBi and 40% at 1575 GHz, respectively.

Ground slot with capacitor for high isolation between MIMO antenna

In this paper a T-shaped ground slot with a chip capacitor to improve isolation between two closely packed planar inverted F antennas (PIFAs) is presented at the WLAN band of 2.4 GHz – 2.48 GHz for mobile phone applications. The calculated envelop correlation coefficient of the proposed antenna is less than 0.1 and the isolation between two PIFAs yields less than −20 dB over the whole WLAN band. The measured antenna gain and efficiency are about 2 dBi and 40% at 2.4 GHz, respectively. The size of the proposed slot with a chip capacitor is also reduced by 50% compared to the T-shaped slot without one.