Multichip

Metal powder—glass powder—binder mixtures are used to apply conductive (or resistive) coatings to ceramics or metals, especially for printed circuits and electronics parts on ceramic substrates, such as multichip modules. Multiple layers of aluminum nitride [24304-00-5] AIN, or aluminay ceramic are fused with copper sheet and other metals in powdered form. The mixtures are appHed as a paste, paint, or slurry, then fired to fuse the metal and glass to the surface while burning off the binder. Copper, palladium, gold, silver, and many alloys are commonly used. 

A substrate is a robust element that provides mechanical support for the die. It can be mounted with more than one die such packages are called multichip modules. Because parasitic capacitance effects are directiy proportional to the dielectric constant, substrate material should have a low dielectric constant. 

Single-crystal sUicon has also been employed as substrate material, particularly in multichip module (MGM)-Si appUcations. As a substrate, sUicon offers good thermal conductivity and matches the GTE of the devices mounted on it it does, however, have a relatively high dielectric constant and is very britde. 

M. Pecht, Integrated Circuit, Hybrid, and Multichip Module Package Design Guidelines M Focus on Keliability,]ohxi Wiley Sons, Inc., New York, 1994. 

Since the end of the 1970s, the polyimides have been introduced for the production of electronic components mainly for the passivation. But more and more they are interesting for the integrated circuits and multichip modulus fabrications. Processability and dielectric and thermomechanical properties are the most attractive features of these materials for the electronic31 and electro-optical applications.32... 

Mucor miehei, 84 Multiblock copolymers, 7-8, 26 Multichip modules, dielectrics for, 270-271 Mylar, 21... 

Gillot C, Schaeffer C, Bricard A (1998) Integrated micro heat sink for power multichip module. IEEE Trans Ind Appl 36(1) 217-221... 

Pricing as well as reliability considerations have led to an almost exclusive use of Si-based (i.e. Si and SOI) micro machined devices. Packaging and assembly has focused on ceramics (A1203, AIN, Low Temperature Co-fired Ceramics LTCC), Printed Circuit Board (PCB-) and Surface Mount Device (SMD-) technology and multichip modules (MCM s). 

Advances in the speed and complexity of integrated circuits and multichip modules (MCMs) have created a demand for the development of high-density... 

To date, most microhotplate-based chemical sensors have been reahzed as multichip solutions with separate transducer and electronics chips [16-19]. The co-inte-... 

Diffusion Barriers. Diffusion barriers are used in the production of various components in the electronic industry. For example, electrochemically deposited nickel is used as a barrier layer between gold and copper in electronic connectors and solder interconnections. In these applications the product is a trilayer of composition Cu/Ni/Au. In another example, Ni and Co are considered as diffusion barriers and cladding materials in the production of integrated circuits and multichip electronic packaging. In this case the barrier metal (BM), Co or Ni, is the diffusion barrier between conductor and insulator (i.e., Cu and insulator), and the product trilayer is of composition Cu/BM/insulator. The common couple in these applications is the Cu/BM bilayer (BM, the diffusion barrier metal Co, Ni, or Ni-Co alloy). 

Fig. 28. Schematic for LC polyester thin film solid state processing of multichip electronic modules...

Stability for use in optical interconnects. In the near future, optoelectronic integrated circuits and optoelectronic multichip modules will be produced. Materials with high thermal stability will thus become very important in providing compatibility with conventional 1C fabrication processes and in ensuring device reliability. Polyimides have excellent thermal stability so they are often used as electronic materials. Furuya et al. introduced polyimide as an optical interconnect material for the first time. Reuter et al. have applied polyimides to optical interconnects and have evaluated the fluorinated polyimides prepared from 6FDA and three diamines, ODA (3), 2,2-bis(3-aminophenyl) hexafluoropropane (3,3 -6F) (4), and 4,4 -6F (2), as optical waveguide materials. 

Multichip Packaging. A solution to these problems is to mount a number of ICs closely together on a common substrate within an MCP. The obvious advantages of the MCP are the reduction in the overall size and weight of the package and, thus, the reduction in the size and cost of the system. The reliability of the system is also improved, because the chip-to-chip interconnections can be accomplished within the package, which reduces the number of package-to-board connections. 

Figure 7. Metallization pattern for the top layer of a 2.25 by 2.25 in. (5.1 by 5.1 cm) multichip package, with chip footprints, I/O pads, and other surface...

Thick-Film Multilayer. Thick-film multilayer technology has been used for many years to fabricate hybrid circuits that interconnect small-scale ICs or discrete components on a ceramic or metal substrate (67-70). This technology has also been used for multichip packaging of more highly integrated ICs for large computer applications. 

The top of Figure 12 shows a thick-film multilayer multichip package used in a mainframe computer (Honeywell DPS 88) (71), and the bottom shows the signal lines on an internal metal layer in this package. The package... 

Figure 12. Thick-film multilayer multichip micropackage for the Honeywell DPS 88 mainframe computer. Top, completed package populated with chips bottom, internal conductor layer with signal lines.

In the multichip package, a variety of pretested chips (e.g., bipolar, MOS, and GaAs) and discrete components (decoupling capacitors and termination resistors) may be mounted on the high-density interconnection substrate. This approach is sometimes termed hybrid-wafer-scale integra-... 

---