Elaboration of Assembly and Connection Technology

In much the same way as the production process is elaborated, the assembly and connection technology (ACT) is elaborated in this phase on the basis of the solution concept for the production process. Progress parallels and closely interacts with design of the 3D electronics. Initial clarification focuses on ascertaining whether, as detailing increases, the product is still compatible with the production process. The ACT process chain is then elaborated and test procedures are selected. The result is the elaborated production process of the ACT. 

As is the case with elaboration of the production process, prior to elaboration of the ACT process chain the compatibility between the detailed product and the assembly and connection technologies selected in the production concept is rechecked. For example, large, solid components act as heat sinks in the vapor phase and impair solderability. The product data are analyzed and compared with the solution concept for the production process. It is important to clarify the extent to which the choice of material and the design of the interconnect device and the components to be used are compatible with the selected assembly and connection technologies. The following are product properties that particularly require consideration in this context  

The resulting requirements and restrictions for the ACT have to be clarified jointly with the mechanics and electronics developers and the production specialists. Once compatibility has been established the selected processes can be elaborated. 

The work processes from the process sequence partial model are detailed, with the work steps being defined on the basis of the production concept and the intermediate steps such as cleaning inserted. In the rehow soldering process the work steps are solder-paste application, component placement, and rehow soldering. 

The handling system suitable for the production conditions (e.g., existing product lines and planned number of units) also has to be selected. Guidelines for these process steps are VDl 3712 Determining the Machine Capability of Dispensing Sj tems and VDl/VDE 2251 Precise Mechanical Elements Connections Survey. The production structure partial model is also detailed at this stage. Equipment available in the company is analyzed and selected. The choice is restricted by product requirements such as the size of the module and the temperature resistance of the electronic components. Vapor-phase ovens, for example, make for much better precision and uniformity of temperature distribution. Process parameters such as placement sequence and temperature-transient control are defined for the individual items of equipment. Criteria include the nature and mass of the electronic components and the melting point of the solder. 

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