In line with the variety of applications, the requirements that apply to the functionality, integration density, reliability, and costs of electronic modules have increased enormously, and this in turn has driven the demand for mechatronic solutions. On account of the high degree of design freedom they allow, molded interconnect devices (MID) permit highly integrated systems and, consequently, open up a huge potential for rationalization with regard to the production process. This chapter outlines the technological basics, possible areas of application, and the latest technological developments.
Materials are products that integrate in a number of production steps into an end product, or that can form the end product by themselves. Modern materials science broadly classifies materials as belonging to any of five major groups: metals (e.g., aluminum or magnesium).
There are various plastics shaping processes that can be used in MID production. Shaping by one of the three mainstream plastics forming processes, one-shot injection molding, two-shot injection molding, or insert molding, is followed by structuring and metallization, the next steps in the MID process chain. This chapter begins by looking at the various structuring technologies before moving on to metallization and its process variants, characteristics, and possibilities.
This chapter opens with an explanation of the underlying principle and the challenges of assembling three-dimensional bodies. It then goes on to study various methods of automatic component placement on three-dimensional circuit carriers and assess their suitability for MID production. MID-related changes that have to be made in the individual process steps are also explained.
Broadly speaking, the connection mediums and techniques familiar from conventional printed-circuit board technology can be used for mechanically locating and electrically contacting electronic components on MID. Soldering, conductive-adhesive gluing, bonding, and flip-chip placement are all in successful use under series-production conditions.
As explained in Chapter 2, because of ongoing developments in the technology, MID are now used in very large numbers in series-production applications and, to an ever increasing extent, in safety- and security-relevant systems. It is clear from this range of applications that product quality of the three-dimensional interconnect devices is a crucial aspect. This in turn means that the groundwork for end-to-end quality assurance has to be laid in both the development and production of the modules.
It is always a good idea to have samples or prototypes of a new product available as early as possible in the product development process. They are used for feasibility studies and assembly studies, to validate the intended choice of production technology, and for selection or decision-making processes, for example. The different stages of the product development process are frequently identified by category A, B, C, or D samples. Category A corresponds roughly to the concept models in this chapter, in other words the simplest models. Category B samples are frequently known as demonstrators or lab samples and in the current context are more or less the same as the fully functional samples. Category C samples are known here as prototypes and are generally used in the process of approvals testing for pre-series production. Category D samples correspond to pre-series models that are used for initial sampling by customers and customer validation as essential steps toward the issue of series-production approval.
The development of innovative MID products calls for interaction between mechanical and electronics development as equals. The integral design that is typical of MID strengthens interdisciplinary dependencies, because changes in the individual specialist areas influence each other. The integration of mechanical and electronic function carriers in a single component, moreover, leads to numerous interactions within the MID. There are also strong interdependencies between MID product and MID production process. The product concept is determined at an early juncture by numerous restrictions of potential MID production methods. This is why the product and the production system have to be developed in parallel and integratively from the beginning. These are the challenges, but MID technology also affords tremendous advantages over conventional approaches (Chapter 2).
The multiplicity of series-production applications underscores the positive development that MID technology has undergone along the entire process chain: this applies to substrate materials, production processes, systems technology, and 3D assembly. There has been a significant increase in the number of these series-production applications. The MID Survey 2006 identified only eight new series-production applications for the period 2003 to 2006. The MID Survey 2011 counted more than forty MID applications in series production. Nondisclosure agreements, moreover, keep many other applications out of the public domain.
