Masahide Tsukamoto

A Stud-bump-bonding Technique For High Density Multi-chip-module

technique for high density Multi-Chip-Module (MCM), using called Stud-Bump-Bonding (SBB) technique, which can bond bare LSI chips directly to ceramic substrate. Au bump is formed on electrode pad of LSI chip by a wirebonding apparatus. Each Au bump has two-stepped construction and bonded with a conductive adhesive to an electrode terminal formed on the ceramic substrate. The conductive adhesive is very flexible and strong in bond, thus resisting thermal and mechanical stresses. Moreover, repair technique has been developed. 100 ,u m pitch electrode pads of LSI chip can be bonded to electrode terminals. The bonding resistance is less than 50 m i l . memory module. High density and reliability in bonding for MCM have been attained by the SBB technique. We have developed advanced flip-chip bonding We have applied the SBB technique to high density MCM for

Pitch and Sense of Helix in Mixtures of Optically Active Azo or Azoxy Compounds and Nematic Liquid Crystal

Mixtures of azo or azoxy compound with asymmetric side chains and a nematic liquid crystal, and the pitch and sense of the helix were examined. Compounds with two identical optically active side chains exhibited the twisting power twice that of compounds with one optically active side chain. As a result, it was found that a feature value (M/Pc), where M, P and c are molecular weight, pitch and concentration by weight, is inherent to an optically active side chain and that the value is additive for compounds with two optically active side chains.

Characteristics of a SAW filter with three inclined and tapered transducers

Inclined and tapered three‐transducer configuration (ITTT configuration) is proposed which consists of three tapered interdigital transducers, a central IDT for an input and two outer IDT’s for an output which are inclined with respect to the central IDT. Characteristics of a surface‐acoustic‐wave filter having the ITTT configuration were calculated and compared with those of a filter having a conventional configuration. It was found that the ITTT configuration brings about smaller ripple in the amplitude response and in the group delay, and also wider tolerances for source and load impedances. Experiments were carried out using a piezoelectric ceramic. The results agreed well with calculations. An insertion loss of 10 dB and a ripple of group delay less than 50 nsec were attained, experimentally.

TTE suppressed surface acoustic wave filter

A new design of SAW filters having an inclined and tapered three transducer (ITTT) configuration is effective for the suppression of the triple‐transit (TTE) caused by the regeneration of an surface acoustic wave. In the ITTT configuration, the electrode fingers of the transducers are not parallel with each other but are tapered, and further, each of the outer output transducers is inclined with respect to the central input transducer. A video i.f. filter for TV having the ITTT configuration was fabricated using a piezoelectric ceramic substrate. The filter exhibited an insertion loss of 9.6 dB and ripple in the group delay of less than 50 nsec.

Experimental results on SAW filters with one bidirectional and two unidirectional transducers.

SAW band pass filters were examined, in which three-transducer configurations consisting of one bidirectional transducer for an input and two group-type unidirectional transducers for an output are employed. The configuration has advantages, such as easy design for frequency responses, a low insertion loss and easy fabrication. Experiments were carried out using ceramic and LiNbO3 substrates. An insertion loss of 6.5 dB and ripples of group delay less than 100 nsec were obtained, showing that the configuration can be applied to a TV-intermediate-frequency filter with a high performance. It has been found that the good results are due not only to the directivity of the unidirectional transducers, but also to the inherent properties of the three-transducer configurations. Therefore, the improvements of the matching circuit and the phase shifters will result in better performance.

Some Types of SAW Filters Effective for TTE Suppression

It was shown from calculations for SAW filters with complex transducer configurations that some types of three-transducer configuration have advantageous properties for suppression of the TTE (triple transit echo), when compared with conventional three-transducer configurations. The conditions effective for suppression of the TTE were obtained for each type by numerical calculation. It was found that the conditions obtained for the non-apodized inclined and tapered three-transducer configurations are applicable to the apodized one. To confirm the calculation, three types of SAW filters were fabricated using piezoelectric ceramics. The results showed good TTE suppression as predicted by the calculations.

Next generation ALIVH substrate for bare chip direct mounting

The next generation ALIVH(R) substrate named ALIVH(R)-FB substrate was developed. The ALIVH-FB substrate has a structure that fine layers were formed on the surface of the conventional ALIVH substrate. The design rule of the core layer is Line/Space (LIS)=50/50 /spl mu/m, Via hole diameter/Land diameter (V/L)=120/250 /spl mu/m and the rule of fine layer is L/S=25/25 /spl mu/m, V/L=50/150 /spl mu/m. Three technologies are developed: thin insulator layer by the film material with high heat resistance; fine via hole drilling process by the YAG THG laser and fine interconnection technology using conductive copper paste; and fine layer fabrication by the transfer process. The technologies display the following features: high wiring density by the Fine Via on Via structure; film insulator with high heat resistance and low CTE for a high reliability joint between the bare chip and the substrate; good impedance control for the high frequency circuit; and a flat surface and high heat resistance for the bare chip mounting. The ALIVH-FB substrate is very suitable for the high pin count bare chip direct mounting.

Design of SAW Filters Having Inclined and Tapered Three-Transducer Configuration

A design method for SAW filters with the inclined and tapered three-transducer (ITTT) configuration is described, in which the frequency response of the filter is expressed by an equation utilizing the δ-function model and the apodization is obtained by the least-squares method. Good results were obtained for an example of a TV-intermediate-frequency filter with a non-symmetric amplitude and a linear phase response. However, to design a non-linear phase response, the theory needs to be extended.