Hybrid microcircuits

Multichip modules (MCM) are basically extensions of hybrid microcircuits, the differences being in their higher degree of density and improved electrical 

MCM-C interconnect substrates are produced from either low-temperature cofired ceramic (LTCC) or high-temperature cofired ceramic (HTCC). Either process can produce multilayer substrates having high numbers of conductor layers (up to 100), although for most applications 2-20 layers are sufficient. The fabrication of MCM-C involves thick-film processes that have wider lines and spacings (5-20 mils) than MCM-D, but are lower in cost. 

MCM-Ls are multichip modules whose interconnect substrates are produced from plastic laminates similar to PWBs, but having much finer dimensions. 

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RAC publications include data summaries for specific component types, such as hybrid microcircuits, small, medium and large-scale integration digital devices, linear and interface devices, digital monolithic devices, and discrete semiconductors. In addition, there are reliability and equipment maintenance data books that provide the failure and repair time data on military electronic equipment by application such as subsystem. 

HYBRID MICROCIRCUIT TECHNOLOGY HANDBOOK by James J. Licari and Leonard R. Enlow... 

Hamer, D. W. Biggers, J. V. Thick Film Hybrid Microcircuit Technology Wiley-Interscience New York, 1972. 

Fig. 4.5 Film devices and circuits (a) thin-film resistors on glass and steatite substrates (b) thick-film resistor networks on snapstrate alumina substrate (c) various thick-film resistors (d) hybrid microcircuits. (Components kindly supplied by General Hybrid, C-MAC and...

Schantz, L.E. and Pusch, J.H., Infrared Baking of positive Photoresist Application for Hybrid Microcircuit Fabrication . Technical Report BDX-613-1256, Bendix Corporation, Kansas City, Missouri (1976). 

Licari,J.J. Perkins,K.L. Caruso,S.V. Guidelines For The Selection of Electrically Conductive Adhesives for Hybrid Microcircuits, NASA CR-161978, 1981. 

Adhesives may substitute for wire or solder in forming electrical connections for example, in connecting capacitors, resistors, or semiconductor devices to a printed-wiring board or to a thin-film or thick-film hybrid microcircuit. The best and most... 

In assembling hybrid microcircuits or multichip modules, ceramic interconnect substrates fabricated using thin-film or thick-film processes are attached to the inside base of a ceramic or metal package. Generally, film adhesives that have been cut to size are used to attach large substrates (greater than 1-inch square) while either paste or film adhesives may be used for smaller substrates. Substrates may be alumina, beryllia, aluminum nitride, or silicon. 

Adhesives in both paste and film form have been used to attach and seal ceramic or metal lids to cavity packages that may also be ceramic or metal. These packages cannot be considered hermetic in the sense that seam-sealed, welded, or soldered fids are, but they are adequate for most commercial and consumer electronics where extreme moisture-temperature environments are not encountered. Packages sealed with Epo-Tek H77 epoxy adhesive are reported to provide near-hermetic sealing of hybrid microcircuits, integrated-circuit devices, and MEM packages withstand 100 hours of 95% relative humidity."... 

Multichip packaging involves the attachment and interconnection of a variety of chip devices on an interconnect substrate that may be single layer or multilayer. There are two basic types of multichip packaging hybrid microcircuits and multichip modules. 

Id meet to qualify and assure a reliable part. This assignment, undertaken by NASA MSFC in 1974, led to the first document for the procurement of adhesives to be used in hybrid microcircuits. After further coordination and revisions, this initial document was formally released as a specification in 1978 and revised in 1982 as NASA MSFC-SPEC-592, Specification For The Selection and Use of Organic Adhesives in Hybrid Microcircuits." For the first time, the critical requirements for ionic contaminants, electrical resistivity, die-shear strength, corrosivity, and outgassing were specified. Work on the development and evaluation of adhesives continued into the mid-1980s and, as a result, several commercially available adhesives were qualified." ... 

Licari JJ, Enlow LR. Hybrid Microcircuit Technology Handbook. 2nd ed. Noyes Publications 1998. 

Swanson DW. Qualification of a High-Purity, Low Outgassing Conductive Adhesive for Hybrid Microcircuit Assembly. Proc 3rd Annual SAMPE Electronic Materials and... 

Performance Specification, Hybrid Microcircuits, General Specification, MIL-PRF-38534. 

Shores AA. Adhesive Bonding Hybrid Microcircuit Substrates with PEEK Thermoplastic Film. ISHM Proc. 1988 1(2). 

Of the mass-transfer dispensing methods, screen printing and stencil printing are the oldest and most widely used. Screen printing has been used for over 40 years in the electronics industry to apply thick-film conductors, resistors, and dielectrics in fabricating circuits on ceramic and plastic-laminate substrates. Screen printing is also used as a batch process for depositing electrically conductive and insulative adhesives to interconnect devices on thin-film and thick-film hybrid microcircuits. 

Adhesives used for screen or stencil printing in surface-mount applications are generally electrically insulative types whose functions are mechanical attachment and thermal dissipation. However, electrically conductive, silver-filled epoxies have been used for many years as ohmic contact adhesives to interconnect bare-chip devices in hybrid microcircuits and are used as solder replacements for surface mounting of components on printed-circuit boards. Regardless of their... 

Benson RC, Romanesko BM, Hall BN, DeHaas N, Charles HK. Current leakage failures in hybrid microcircuits. EEE Trans. On Components, Hybrids, and Mfg. Tech Dec. 1986 4 403 09. CHMT-9. 

Shores AA. Adhesive bonding hybrid microcircuit substrates with a thermoplastic film. SAMPE Quarterly. Apr. 1988 19. 

Figure 5.6 Example of a ceramic multichip module (MCM-C) and a hybrid microcircuit. Top MCM-C fabricated from high-temperature cofired ceramic. Source Honeywell Sohd State Electronics Center. Bottom Multilayer thick-film hybrid microcircuit.

Hybrid microcircuits MIL-STD-883, Method 5011- materials Silver-filled or insulative... 

Hybrid microcircuits, performance specification. General Specification, MIL-PRF-38534. Total Mass Loss and Collected Volatile Condensable Materials from Outgassing in a Vacuum Environment, ASTM E595, American Society for Testing and Materials. 1999. 

Perkins KL, Licari JJ. Development of low-cost, high-reliability sealing techniques for hybrid microcircuit packages. NAS-831992, http //ntrs.nasa.gov/details.jsp R=311623 Aug. 1977. 

Poor adhesion and delamination can also result from dispensing insufficient adhesive to cover the entire bond line (Fig. 6.2). Generally, a minimum thickness of 2 mils is required. A visible fillet around two or more sides of an attached die or substrate provides assurance that sufficient adhesive has been used and has spread and covered the bond line. In fact, the appearance and extent of fillet are inspection criteria for the acceptance of high-reliability circuits as defined in MIL-STD-883, Method 2010 for monohthic ICs and Method 2017 for hybrid microcircuits. According to these methods, at least 75% of the fillet should be visible along each side of the device. Applying a uniform thickness is also important. Nonuniform thicknesses result in tilted devices with the potential for cracking and separation. 

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