Assembly Technology for 3D-MID

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. 

The processes generally employed to fix electronic components on three-dimensional circuit carriers are reflow soldering and electrically conductive-adhesive gluing. The first step in reflow soldering is to print solder paste on to the pads of the circuit trace (Fig. 4.1). The electronic components are subsequently placed in these solder depots. The module, complete with its electronic components, is then heated in a reflow oven, the solder particles of the paste melt, and the molten solder flows over 

FIGURE 4.1 Process chain of reflow soldering or electrically conductive-adhesive gluing processes with application of the interconnection medium, placement of electronic components, and remelting of the solder or curing of the conductive adhesive 

The steps in the conductive-adhesive gluing process are not unlike those in reflow soldering. Conductive adhesive Is applied to the pads of the circuit carriers by a conventional printing process. Placement of the electronic components is followed by curing of the adhesive. The three-dimensionality of interconnect devices entails elevated requirements for medium application and for component placement, particularly in terms of process automation. 

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Once the interconnection medium has been applied, the next step is to place the electronic components. Current advances in MID technology and the growing number of series-production applications have given the market a variety of production systems for automated 3D-MID assembly and placement. In terms of implementing 3D assembly, they all satisfy the primary requirement the component s joining direction must be normal to the process surface. The systems achieve this by integrating additional degrees of freedom and drives in various kinematic variants (Fig. 4.12). Broad distinctions between these kinematic variants can be drawn as follows ... 

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