The Programmable Multichip Module (PMCM) consists of a Low Temperature Cofired Ceramic (LTCC) substrate, sealed active components, and accessible support components that can be changed, or programmed. Three key features make the PMCM unique—segregation of the active from the support components; accessibility to the support components; and the programmable capability. Flexibility and efficiency are enhanced by the variety of sealing methods that can be used to protect the active components.
Design and configuration innovations of the PMCM start with the LTCC substrate. By using this substrate to form the package, module designers have eliminated the metal packaging needed for conventional hybrid assembly techniques. This improves module design and configuration. The PMCM design groups the active components together; they are attached to the substrate using standard microelectronic assembly techniques. Wire bonding secures the electrical interconnections. Once covered, the active components are fixed and protected.
Support components are also grouped together but physically separated from the active area. Reflow soldering secures the uncovered support components. This well-known technique provides functional reliability, yet yields sufficiently to let users remove and replace individual support components at any point in the design and development process. This access lets the user program the module for different applications of the same basic circuit. With special test fixtures, the active components of the PMCM can be functionally tested without the support components. Then support components can be selected and attached to the PMCM to meet specific circuit designs.
The PMCM brings increased flexibility of configuration to designers of microelectronics. Modules are made from readily-available commercial materials; functionality is supplied by commercial components, custom-designed components, or any combination needed to meet the design specification. The active and support areas can be placed on separate sides of a two-sided module, or they can be segregated on a single side.
The new module accepts any of the standard enclosure methods, from encapsulation for inexpensive mass production to commercially available, hermetic sealing techniques. The PMCM can be made in any size to meet specific application requirements. For example, the two-sided design is useful where size is a concern while the single-sided configuration is used for modules with extremely fast electronics that are expected to generate excessive heat. The underside of this PMCM uses a heat sink to dissipate heat build-up.
Component segregation improves module operation. The active and passive components are electrically interconnected with vias in the substrate or with edge clips. Traditional electronic systems usually locate the support electronics on the Printed Wiring Assembly (PWA). These PWAs create longer interconnects and require more area. The PMCM integrates the support components into the same package, allowing for the shortest possible interconnections of the active and support components. This design enhancement improves overall electrical performance and can reduce the number of next assembly interconnects.
The PMCM’s innovative design and configuration introduces new flexibility in microsystem use and reuse while providing cost savings and improved operating efficiencies. Flexibility makes the PMCM attractive for mass production uses, while its reliability is ideal for high-performance applications.
This technology is patented under U.S. Patent No. 6700196.