Question

(a) Perform a GRR study using Method I based on the data shown in Table 3. Include all the steps covered in Topic 5. The specifications are 60 ± 20 grams. Assume that Pa must be smaller than 0.2 based on the 6-sigma PIT formula. Show that the ball shear tester meets the requirement.

(b) Should there be a switch in the bonding temperature from 280°C to 240°C? Using Approach 2 of process capability analysis, do an SPC study based on the information and data given in Tables 1 and 2. Show your work clearly and give your recommendations, including the justifications and assumptions made, and any possible limitations. The lower specification limit of the ball shear strength is 40 grams (the unit used in Table 1 and 2). The upper specification limit is not applicable and can be ignored. Assume that the required Cs is at least 1.5.

(c) Compare and comment on the process FNC that would be generated at the two different levels of bonding temperature.

(d) At 240°C, what should the LSL be to achieve a Cs of exactly 1.5?

(e) The process engineer pointed out that at 240°C the process means can be increased by 10% from the currently observed level through adjusting another process parameter. Assume that this 10% improvement is achievable and LSL is 40 grams. Compute the maximum process standard deviation that would give a Cpk of at least 1.5.

Table 1: Data on the ball shear strength (X) collected at a bonding temperature of 280°C.

Table 2: Data on the ball shear strength (X) collected at a bonding temperature of 240°C.

Table 3: Data for a GRR study for the ball shear tester.