On the use of yielded cost in modeling electronic assembly processes

Abstract

Yielded cost is defined as cost divided by yield and can be used as a metric for representing an effective cost per good (non-defective) assembly for a manufacturing process. Although yielded cost is not a new concept, it has no consistent definition in engineering literature, and several different formulations and interpretations exist in the context of manufacturing and assembly. In manufacturing, yield is the probability that an assembly is non-defective. To find the effective cost per good assembly that is invested in the manufacturing or assembly process, cost is accumulated and divided by the yield at the end of the process. This paper reviews and correlates existing yielded cost formulations and presents a new approach that enables consistent measurement of sequential process flows. This new approach defines the yielded cost associated with an individual process step (step yielded cost) as the change in the process's yielded cost when the step is removed from the process. This approach is preferred because it incorporates upstream and downstream information and because it provides a prediction of a specific process step's effective cost per good assembly that is independent of step order between steps that scrap defective product.

A new test/diagnosis/rework model for use in technical cost modeling of electronic systems assembly

“…Yielded cost is defined as cost divided by yield. In electronic assembly, yielded cost represents the effective cost per good (non-defective) assembly for a manufacturing process [14]. Figure 5 shows that when false positives are created and rework yield is low, there is an optimum number of rework attempts per part (2 for Y rew = 30%, 1 for Y rew = 10% or less).…”

Optimization of Test/Diagnosis/Rework Location(s) and Characteristics in Electronic System Assembly

“…The yielded cost we are interested in is the final cost per product instance (after the final processing step and/or TDR operation) divided by the final product yield (see [11] for a discussion of "yielded cost"). This yielded cost gives a measure of the effective cost per good product instance after all the manufacturing and TDR operations are completed.…”

The Economics of Embedded Passives

“…The critical yield parameter not explicitly considered is the board yield (see Chapter 8). The foregoing discussion effectively assumes that the layer pair cost with embedded passives, C new pair layer , computed in ( 13) is a yielded cost, i.e., the cost per good (non-defective) layer pair, [18]. This quantity can be interpreted as yield Figure 4 -Application-specific economical regions of trimming and reworking embedded resistors.…”