Integrated devices in varied formats at KOA Speer

Electronic News, Nov 3, 1997 by Scott Brown, Brian Piscitelli

KOA's integrated passive components are available in two different forms, chip resistor arrays and silicon-based networks in a molded package. The former type, chip resistor arrays, are available bussed, isolated and custom resistor and resistor/capacitor networks; the performance characteristics of these devices are that of typical thick-film technology for the resistors and X7R type performance for the capacitors. Package options Include the concave and convex type termination.

There are distinct advantages in using the chip resistor arrays. They include cost savings when placement costs are factored in and excellent tracking from one resistor to another within the same array. The tracking includes both resistive tolerance tracking and TCR tracking. Typical component placement costs for discrete components exceed 2 cents per component, The chip resistor array allows the electronics manufacturers to reduce their placement costs while at the same time reducing PCB assembly time by reducing the number of component placements per panel.

Thin-film Passives

The second type of integrated passive components, thin-film passive components, are designed for EMI/RFI filtering and impedance matching applications. These integrated passive components are produced using a silicon-based technology which reduces the size and the weight of using individual components while improving their electrical performances. Like the chip resistor arrays, these thin-film components also have excellent TCR tracking and ratio tolerance tracking. The components can track to plus/minus 5ppm/C for TCR and plus/minus .05 percent for ratio tolerance tracking.

This network product line is available in resistors, resistors/capacitors, and diodes in various circuit configurations as well as custom application specific circuits. KOA's Integrated Passive Components are available is QSOP, TSSOP, Narrow SOIC, Wide SOIC, DIP, SOT-23 and chip scale packaging.

The Chip Scale packaging is a wafer level packaging technology that offers the designer the highest level of packaging density for passive components as well as superior electrical performance. The elimination of bonded Interconnects between the lead frame and the passive circuit results in enhanced stability at high frequencies by minimizing lead inductance. KOA's Integrated Passive Components product line is used in laptop computers, PCMCIA cards and memory applications where board real estate and functionality are crucial. Other applications also include precision voltage dividers, T-filters, L-filters, D/A and A/D converters and terminators.

Responding to customer needs that have become apparent as a result of the technological shift towards digitalization, KOA recognizes the limitation of thick-film resistor technology. The graph on this page represents the frequency characteristic of a typical thick-film chip resistor.

The resistance characteristic of thick-film technology attenuates significantly above 20MHz. This characteristic is due to parallel capacitance in the resistive circuit that Is intrinsic to metal oxide films. New resistive materials being worked on by KOA will extend the usable frequency range of general purpose resistors and at the same time offer a cost advantage over thin-film technology typically utilized for these high frequency designs.

As an additional benefit of this project better capacitance/frequency characterization of our thick-film resistors is being developed to be used by designers who choose to continue to use current thick-film technology knowing the expected performance of the resistor. Spice modeling will also be provided to designers to assist them in reducing the product development cycle.

Scott Brown is a quality control manager and Brian Piscitelli is a quality product manager at KOA Speer Electronics.