Search

Nonconductive film (NCF) interconnection technology is now being used for the ultrafine pitch interconnections in chip-on-glass (COG) packaging. In comparison to traditional anisotropic conductive film (ACF) technology, NCF can reach less than 10 [micro]m ultrafine pitch interconnection, while ACF just reaches the limit of 30 [micro]m. For NCF interconnection technology used in COG bonding, it needs a higher bonding pressure and temperature than those in ACF bonding, so the warpage is very important for the reliability of the package. In this paper, an exploring study investigated the effects of the structure design and bonding process on the warpage in a COG module. The warpage increased linearly with the increase in bonding head temperature and bonding force, but it decreased with the increase in substrate temperature, substrate thickness, and chip thickness. The large temperature difference between the substrate and chip produced a high thermal stress, and the large bonding force generated a high mechanical stress. The thermal and mechanical stresses were the reasons for warpage in a COG module. For the high reliability, the design and bonding process to the COG module with NCF should adopt a thick substrate, an appropriate bonding force, and a low temperature difference. [DOI: 10.1115/1.4000361] Keywords: nonconductive film (NCF), chip on glass (COG), warpage, the thermocompression bonding

An electromagnetic model is developed to study the impact of jacket in the characterization of a cable-in-conduit conductor. The model reproduces some unexpected qualitative behaviors of the voltage signals detected on the jacket.

Twelve different commercial compression connectors for 240 [mm.sup.2] stranded aluminum cable conductors have been examined in order to identify and clarify the correlations between the quality of a connector and its design characteristics, assembly procedures, and other relevant parameters. The quality of the connectors is assessed with basis in resistance measurements during short-circuit tests and thermal cycling as specified by the IEC 61238-1 standard. Visual inspections of cross-sectioned connections, hardness measurements, and other examinations revealed that large mechanical deformations in connector-conductor interfaces significantly improve the quality. Connecting soft (annealed) conductors is considerably more difficult than hard-drawn conductors, but excellent results can be obtained if the work hardening during compression increases the conductor hardness to a level approaching that of hard conductors. The sequence in which the compression indents is made can be decisive for the quality of a connector. Unless the connector barrel or sleeve contains excessive amounts of contacting compound, it is advantageous to set the first indents at the ends of the barrel and the last ones in the middle. Index Terms--Aluminum power conductors, connectors, power cable connecting.

A complete full-wave eigenvalue analysis is presented for inhomogeneously filled guiding structures that support TEM mode. The analysis is based on treating the transverse inhomogeneity of the filling dielectric as a polarization current that excites the corresponding empty guiding system. The problem is formulated to determine the quasi-TEM and higher order modes of the system. The mode propagation constants squared appear as eigenvalues of the problem, and the corresponding eigenvectors represent the expansion coefficients of the field modes. The strength of the formulation is verified by its application to the problem of the partially dielectric-filled parallel-plate waveguide. The results of the analysis are compared to the exact solution and a variational solution. The quasi-TEM mode variation versus permittivity and frequency variation is studied. The convergence and dispersion characteristics of the method are presented.

An endurance test for a printed circuit board to ionic migration was carried out for 2000 h in a chamber controlled at 85 [degrees] C and 85%RH. The capacitance C and tan [Delta] between the conductors on the board were measured to find their correlation with ionic migration in the board. The measurement frequency of C and tan [Delta] ranged from 1 to 1000 Hz. The configuration of the test circuit was designed according to IPC-SM-840. The material of the insulating board was fiberglass-reinforced epoxy resin. The distance between the Cu conductors was 0.165 mm, and 70 V dc was applied continuously. In the low frequency region ([is less than] 30 Hz), C and tan [Delta] gradually increase after ~800 h voltage application. During the gradual increase, steeply transient increases in C and tan [Delta] are detected at about the same time when a deposit was seen to have formed on the board between the conductors, although no significant decrease in insulating resistance between the conductors is observed. It was confirmed that the deposit could be detected early from the steep increases in C and tan [Delta] in the low frequency region. In the high frequency region ([is greater than] 30 Hz), on the other hand, gradual slight increases are observed from ~1100 h after voltage application, but no steep increases. The dependence of C and tan [Delta] on frequency at the measurement is due to the low mobility of Cu ions in the water film on the insulating board.