Hughes Aircraft Company

Dennis F Elwell

William R Crumly

Charles B Zarowin

Hal D Smith

Harold C Bowers

Passivating coatings are formed on populated electronic boards, such as a sealed chip on board electronic module, or the like, using a high density plasma deposition method that employs an electron cyclotron resonance (ECR) reactor. A populated electronic board is disposed in the electron cyclotron resonance reactor. A high density nitride plasma is generated by means of electron resonance in the reactor. The plasma is formed adjacent to a magnetic field coil where an ECR condition is established. The high density plasma forms a passivating coating that covers the populated electronic board with a silicon nitride passivating layer. To form the plasma, a mixture of silane and ammonia may be injected into the reactor to produce excited atoms that form a substantially oxygen-free nitride passivating coating. The substantially oxygen-free nitride passivating coating is deposited at a relatively low temperature, typically below 150 degrees Celsius and preferably below 100 degrees Celsius so that the components of the populated board are not damaged.

Passivation of electronic modules using high density plasmas

An inexpensive arrangement for mounting multiple, closely spaced integrated circuit chips (18, 20, 22, 24) on a low temperature co-fired ceramic (LTCC) substrate (10) uses a mandrel-produced thin film decal (26) having patterns of interconnecting conductive traces (34, 46, 47) that connect to the fine pitch connecting pads (60) of the integrated circuit chips at one end and connect to the relatively coarse pitch connecting pads (50) of the low temperature co-fired ceramic substrate at the other end. The interconnect decal is formed independently of the LTCC substrate and is provided with chip connections at a pitch of about 0.004 inches. The interconnect pads of the decal are connected by conductive traces on the decal to the LTCC pads which have a pitch in the order of about 0.01 inches or greater. The decal, which is formed independently of the LTCC substrate, is connected to the substrate pads by one of several different electrically conductive adhesives, including silver loaded epoxy, Z-axis conductive epoxy and anisotropically and isotropically conductive epoxy or low melting temperature solder. The decal enables use of a 'fan-out' arrangement in which connections are routed under the chip.

Multichip module with a mandrel-produced interconnecting decal

An elongated composite tape structure including an elongated carrier, and a plurality of sinterable, thermally fusible tape strips of different characteristics disposed on the elongated carrier. Also disclosed is a reel-to-reel process wherein the composite tape structure as stored on a reel is incrementally processed by longitudinally feeding the tape structure through one or more processing stations at each of which the tape is driven in an indexed manner so that predetermined portions of the tape are processed at each station for substantially the length of the tape structure.

HTCC/LTCC use of multiple ceramic tapes in high rate production

A solid polyhydric alcohol material (16) is provided in thermal contact with an electronic component (14) which will be damaged if its temperature rises above a certain value. The material (16), known as a phase change material (PCM), exhibits an isothermal solid-solid phase transition at a predetermined temperature (T1) below which damage to the component (14) will not occur. Heat generated by the component (14) and its environment causes the temperature of the component (14) and the PCM (16) to increase to the transition temperature (T1). Further generated heat is absorbed by the PCM (16) as latent heat and causes a phase transition, such that no further increase in temperature occurs. This arrangement prevents the temperature of the component (14) from rising above the transition temperature (T1) under transient thermal overload conditions.

Growing community of inventors

San Clemente, CA, United States of America

Dennis F Elwell