Thin-film multilayer packaging

Typical Thin Film Multilayer Package Structure... 

Figure 1. Proposed approach for multichip packaging using thin film multilayer Cu/polyimide interconnections.

Metallization. In the fabrication sequence described in Table I, metal layers are used as conductive paths between points on the same integrated circuit or as contact points between the IC and its package. The metal layers may be single component, multi-component alloys or multilayered thin films depending on the application. The methods used for depositing the metal are... 

Polvimide-Metal Interfaces. Several technological applications including semiconductor packaging and metallization demand a reliable and durable adhesion properties of the metal films. In the development of multilayer devices consist of alternating layers of metal and polyimides several reliable techniques are needed to study both thin films and their interfaces. The usefulness of the nuclear scattering techniques to study the metallization and the associated interfacial elemental diffusion processes under the effects of various temperature and humidity treatments on the metal-polyimide systems, such as Al, Cu, N, and Au on Du Pont Kapton type H have already been reported (21., 22.). Only a couple of examples are presented here to illustrate the ERD application. 

The concept of modern multilayer packaging means that there is a minimum use of plastic material, because various characteristics can be combined into one thin packaging film. The most widely used plastic for combination is PE. The PA-PE combination processed by coextrusion has a good gas resistance. It can be deep drawn, and its fat resistance and IlexibiUty are suitable, too. These combinations are very widely used for vacuum packages. In addition, the PET-PE combination is heat resistant, and the PE-PP is sterilizable. As an illustration of the effectiveness of plastic composites, WilUams presents multilayer plastic... 

Kyocera has been conducting research and development on AIN and LTCC for more than 10 years, and has produced many kinds of AlN and LTCC products, such as Cer-Quad and multilayer packages, in addition to thin film substrates. Now, we have developed three materials for packages. The first is a novel AlN material (AN75W) that can co-fired at low temperature to reduce cost. The second is a novel LTCC that has a high thermal coefficient of expansion close to that for FR-4. The third is also a novel LTCC that has low permittivity... 

These requirements are met with a multilayer structure containing a thicker central layer of the copolymer with thin outer layers of polypropylene (17). Such film structures are made by lamination or coextrusion, respectively using appropriate adhesive or tie layers. Other uses for these films include packaging of personal care and consumer products as in, for instance, blister bottles. 

Multilayer AIN packages are available from a number of vendors. The thermal conductivity of these materials varies from 75 to around 200 W/ m K. The refractory metallization can be plated and brazed with high reliability. However, reliable postfire metallization is limited to thin-film and noble-metal compositions. Good refractory (W or Mo-Mn) metallizations have been promoted by several suppliers. 

Aramid-reinforced laminate and prepreg allow fast microvia hole formation and at the same time maintain the performance characteristic of a smooth surface for fine-line conductor imaging. The ablation speed of non-woven (aramid) laminates and prepregs is close to that achieved when using nonreinforced materials such as resin-coated foil, dry film, or liquid dielectrics. Since aramid laminates are very stable, they allow the fabrication of doublesided, very thin, etched innerlayers, which are then pressed to a multilayer package in a single... 

The melting point can also be determined in a penetration-mode measurement, which is important in the characterization of multilayer polymer hlms and coatings. Multilayer thin films are used primarily as packaging materials in order to control the end-use properties, such as selective atmosphere permeability or toughness. TMA in the penetration mode can characterize multilayer films in terms of layer thickness as shown in Fig. 4.11. Here, a multilayer film coated on a foil substrate was characterized in a penetration-mode experiment. Two distinct changes due to the penetration of the probe are clear at 103 °C and 258 °C, suggesting that two layers of film were coated onto the metal substrate.The thicknesses of the layers were measured as 93 pm (polymer 1) and 15 pm (polymer 2). These temperatures are close to the melting points... 

Aluminum nitride has been demonstrated to be suitable for blank substrates for high power and high frequency applications. Substrates from many sources are available for thick or thin film metaUization. Thick film paste manufacturers now supply pastes formulated for aluminum nitride. The multilayer process described in the previous section has also been adapted for aluminum nitride. Both multilayer substrates and packages are available commercially. 

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