VISHAY DALE THIN FILM www.vishay.com Film Resistors Technical Note Vishay Thin Film Engineering Test Report PTN - THETA J MEASUREMENTS 1. Background Managing thermal energy in passive devices is a challenge in today circuit assemblies. The demand to reduce the size of electronic assemblies, coupled with the need to increase power levels, has resulted in the need to clearly understand the thermal characteristics of devices. A typical way of quantifying the thermal characteristics of devices is by examining the temperature difference between the highest temperature region of the component and the surrounding areas such as the case or termination and the board or substrate on which it is mounted for testing. Knowing these temperature values, we can calculate the thermal resistance properties which are expressed as Theta J values in °C/W. The typical formulas for these Theta J calculations are as follows: Theta JC = (TJ - TC)/P Theta JB = (TJ - TB)/P Theta JA = (TJ - TA)/P Where: Theta JC = Junction to Case (Termination) Thermal Resistance Theta JB = Junction to Board Thermal Resistance Theta JA = Junction to Ambient Thermal Resistance and: TJ = Junction temperature or in this case the highest temperature region of the film area on the device under test TC = Case temperature or in this case temperature of the termination on the device under test TB = Board temperature or in this case, the temperature of the test cards used for the thermal analysis TA = Ambient temperature of the test lab where the analysis was performed P = Power applied to the device under test 2. Experimental Methods Thermal imaging for this testing was conducted on a range of samples by mounting one device per 2.25" x 4" test card. The test cards were constructed with a 2.5 mil copper metallization on both surfaces. Thermal vias on 120 mil centers provided heat transfer between surfaces of the test card. This test card design, shown in figure 1 below, essentially creates and infinite heatsink for the purpose of this testing. The list of samples tested is shown in table 1 below. TABLE 1 - SAMPLE DETAILS CASE SIZE RESISTANCE VALUE CRITICAL HIGH 0603 10 25.2 k 80 k 1206 10 40.2 k 90.9 k 2512 10 40.2 k 65.5 k Thermal measurements were taken on the device under test using a FLIR SC645 camera equipped with a 50 μm close-up IR lens in the arrangement shown in figure 2 . In order to obtain a range of Theta J values, the devices under test were powered at 1x, 2x, and 3x their rated power. At the time the initial power was applied and during the change in applied power between levels, a video capture of the device under test was made for duration of 3 minutes. During the data analysis, temperature values were obtained one minute into the recording which was determined to be the time for the device to reach a steady state temperature. The location of the temperature readings is shown in figure 1. Revision: 25-Sep-12 Document Number: 60122 1 For technical questions, contact: [email protected] THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 TECHNICAL NOTE LOW Technical Note www.vishay.com Vishay Dale Thin Film Vishay Thin Film Engineering Test Report Fig. 1 TECHNICAL NOTE Fig. 2 Using these temperature readings, and the ambient temperature of the test lab, the Theta J values were calculated using the formulas defined in the background section above. Revision: 25-Sep-12 Document Number: 60122 2 For technical questions, contact: [email protected] THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 Technical Note www.vishay.com Vishay Dale Thin Film Vishay Thin Film Engineering Test Report 3. Results and Discussion Table 2 below, is a summary of Theta J test results. As the data shows, there is good agreement between resistance values, within each case size chip. This data is also represented graphically in figures 3 through 11 of Appendix A. TABLE 2 - THETA J VALUE SUMMARY TEST RESULTS SUMMARY CASE SIZE DEVICE WEIGHT (g) RESISTANCE VALUE () RATED POWER (mW) 10 0603 0.003 25 200 150 80 000 10 1206 0.009 40 200 400 90 900 10 2512 0.033 40 200 65 500 1000 APPLIED POWER (mW) 150 300 450 150 300 450 150 300 450 400 800 1200 400 800 1200 400 800 1200 1000 2000 3000 1000 2000 3000 1000 2000 3000 TJ MAX. (°C) THETA JC (°C/W) THETA JB (°C/W) THETA JA (°C/W) 32.03 40.07 48.58 31.88 39.47 47.87 32.13 42.65 46.25 40.44 58.72 78.03 39.46 54.83 70.79 38.35 53.54 67.01 50.93 77.48 104.69 65.98 112.98 164.07 51.82 82.70 114.96 32.00 34.70 35.25 31.50 31.98 30.38 23.64 27.14 26.82 21.08 21.89 22.55 18.76 20.17 20.63 15.27 15.94 16.36 15.52 15.63 15.98 16.06 16.81 17.16 11.70 15.49 16.06 48.41 49.04 49.28 51.36 49.35 46.24 40.52 45.42 42.59 30.84 31.78 32.52 30.47 31.16 32.08 27.11 27.82 28.32 19.97 19.96 20.14 19.70 20.18 20.84 16.27 20.66 21.14 55.14 54.66 54.50 61.10 57.07 53.09 49.43 53.32 48.50 35.88 37.46 37.70 38.40 37.86 38.16 34.82 34.53 34.61 25.41 24.43 24.50 24.39 24.17 24.94 23.74 25.68 25.88 4. Conclusion TECHNICAL NOTE The results of this testing provide designers with critical thermal resistance information necessary to the design on high density circuit assemblies. The Theta J values we observed are somewhat better than those reported by other manufacturers based on comparable test conditions. Revision: 25-Sep-12 Document Number: 60122 3 For technical questions, contact: [email protected] THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 Technical Note www.vishay.com Vishay Dale Thin Film Vishay Thin Film Engineering Test Report Appendix A TECHNICAL NOTE Fig. 3 Fig. 4 Revision: 25-Sep-12 Document Number: 60122 4 For technical questions, contact: [email protected] THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 Technical Note www.vishay.com Vishay Dale Thin Film Vishay Thin Film Engineering Test Report TECHNICAL NOTE Fig. 5 Fig. 6 Revision: 25-Sep-12 Document Number: 60122 5 For technical questions, contact: [email protected] THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 Technical Note www.vishay.com Vishay Dale Thin Film Vishay Thin Film Engineering Test Report TECHNICAL NOTE Fig. 7 Fig. 8 Revision: 25-Sep-12 Document Number: 60122 6 For technical questions, contact: [email protected] THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 Technical Note www.vishay.com Vishay Dale Thin Film Vishay Thin Film Engineering Test Report TECHNICAL NOTE Fig. 9 Fig. 10 Revision: 25-Sep-12 Document Number: 60122 7 For technical questions, contact: [email protected] THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 Technical Note www.vishay.com Vishay Dale Thin Film Vishay Thin Film Engineering Test Report TECHNICAL NOTE Fig. 11 Revision: 25-Sep-12 Document Number: 60122 8 For technical questions, contact: [email protected] THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000