JCL Inc. is a major chip manufacturing firm that sells its products to computer
ID: 2428040 • Letter: J
Question
JCL Inc. is a major chip manufacturing firm that sells its products to computer manufacturers like Dell, HP, and others. In simplified terms, chip making at JCL Inc. involves three basic operations: depositing, patterning, and etching. Depositing: Using chemical vapor deposition (CVD) technology, an insulating material is deposited on the wafer surface, forming a thin layer of solid material on the chip. Patterning: Photolithography projects a microscopic circuit pattern on the wafer surface, which has a light-sensitive chemical like the emulsion on photographic film. It is repeated many times as each layer of hte chip is built. Etching: Etching removes selected material from the chip surface to create the decive structures. The following table lists the required processing times and setup times at each of the steps. There is unlimited space for buffer inventory between these steps. Assume that the unit of production is a wafer, from which individual chips are cut at a later stage. Note: A setup can only begin once teh batch has arrived at the machine. Process Step 1 Depositing 2 Patterning 3 Etching Setup time 45 min 30 min 20min Processing time 0.15 min/unit 0.25min/unit 0.20min/unit a. What is the process capacity in units per hour with a batch size of 100 wafers? b. For the current batch size of 100 wafers, how long woul dit take to produce 50 wafers? Assume that the batch needs to stay together during deposition and pattering. However, the 50 wafers can leave teh process the moment all 50 wafers have passed through the etching stage. Recall that a setup can only be started upon the arrival of the batch at the machine. c. For what batch size is a step 3 (etching) teh bottleneck? d. Suppose JCL Inc. came up with a new technology that eliminated the setup time for step 1 (deposition), but increased the processing time to 0.45 min/unit. What would be the batch size you would choose so as to maximize teh overall capacity of the process, assuming all units of a batch stay together fo rthe entire process?
Explanation / Answer
Summary of data given in above question.
Answer a. The process capacity in units per hour with a batch size of 100 wafers is calculated as follows.
Capacity= Batch size/(Process time+ Setup time)
By putting the values in above formula to determine capacity of each step.
Capacity(Deposition) = 100/(45+0.15*100)=100/60=1.67 units per min or 100 units per hour
Capacity(Patterning) = 100/(30+0.25*100)=100/55=1.82 units per min or 109 units per hour
Capacity(Etching) = 100/(20+0.2*100)=100/40=2.5 units per min or 150 units per hour
From the above calculation it is clear that Deposition process has minimum capacity per hour.Therefore it would act as bottleneck process. Hence, the total capacity of the fiirm is 100 units per hour.
Answer.b For the current batch size of 100 wafers, to produce 50 wafers will take total of processing time plus setup time as follows.
Capacity(Deposition) = (15min*50units)+45 minutes=795 minutes=13.25 hr
Capacity(Patterning) = (25min*50units)+30 minutes=1280 minutes=21.33hr
Capacity(Etching) = (20min*50units)+20 minutes=1020 minutes=17.33hr
Thus it will take total 3095 minutes or 51.58 hours to produce 50 wafers.
Answer.c As calculated in Answer a above for batch size of 150 units a step 3 (etching) is bottleneck .
Answer d. The batch size of 100 units to maximize the overall capacity of the process,
Process processing time/ minute per unit setup time in minutes depositing 0.15 45 patterning 0.25 30 etching 0.2 20Related Questions
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