1. Company Confidential 1 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Thermal Requirements and Uses Cases for SPR Guideline to SPR Surface Temperature Requirement Steven Cooksey, Olaf Schröder Reference: SPR c3.4.1 V 1.0 2006-Sept-14

2. Company Confidential 2 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Scope of Thermal Requirements in SPR c3.4.1 The thermal requirement in SPR c3.4.1 focuses on surface temperatures and not on component temperatures inside the device. In addition to surface temperature requirements, IEC 60950 also lists requirements for components inside the device. Component temperatures are usually checked by the product programs as part of the “derating” activities. Therefore it does not seem necessary to cover this as part of the Safety SPR. This guideline covers all device surfaces which are user accessible during ordinary use. Example: this includes the keyboard as well as the main display of a fold phone, but not parts inside the battery compartment.

3. Company Confidential 3 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Reasons for Defining Thermal Use Cases Why are use cases necessary to assess the thermal safety concept? Phones have different form factors, include different features and technologies and can be operated in various environments. Therefore it is not possible to predefine any one use case creating the maximum surface temperature. Therefore several use cases have to be defined and measured. The maximum surface temperature from all defined use cases has to be regarded. The defined use cases have to cover the whole range of parameters having impact on the surface temperature. It is not appropriate to combine all parameters with their most severe values in one use case because this would either not be a normal use or not be in accordance with the operating instructions like the user manual or the technical product specification. Realistic use cases have to be sustainable for the time needed to heat up the device surface. For mobile phones, this is in the range of 15 to 30 minutes.

4. Company Confidential 4 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Ambient Temperature for Thermal Use Cases The ambient temperature has a major impact on the surface temperature of the phone in a given use case. Therefore it is necessary to specify the ambient temperature for each use case. Looking at all use cases, the required maximum ambient temperature range has to be covered. What is the total temperature range? According to IEC60950, the lowest value for the maximum ambient temperature is 25 °C. According to IEC60950, the upper value for the maximum ambient temperature has to be specified by the manufacturer. In IEC60065, the ambient temperature is specified to 35°C.  The maximum ambient temperatures for the use cases have to be selected from the range 25° to 35°C.

5. Company Confidential 5 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Thermal use Cases (1/2) „In Car“: 35°C ambient temperature (inside car without air condition). The „short period touching“ limits apply assuming the phone is placed in a holder. Due to moving, the RF conditions (field intensity and fading) will change continuously. So the RF Tx output power for WCDMA for this case is significantly below the max power (6 dB below). As well for GSM a certain variance has to be assumed (2 dB). „Desktop“: 25°C is chosen due to the office environment this use case is assumed in. This use case includes fast data transmission originated from a PC or laptop. The „short period touching“ limits apply assuming the phone is placed on the desk. The RF conditions are fairly static here. The RF tx output power for WCDMA for this case is mainly depending on the population of the cell, therefore fairly close to max power (4 dB below). The GSM Tx output power is assumed maximum.

6. Company Confidential 6 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Thermal use Cases (2/2) „In Hand“: 30°C is chosen due to being outside buildings e.g. in summer. Due to holding the phone in the hand, there are some restrictions on the features to be used for this case. The following assumptions are taken: the video call duration is max 10 minutes, no high speed data in hand, no charging. The RF conditions are slowly changing due to moving. The RF Tx output power for WCDMA for this case is depending on the population of the cell and a margin for fading due to moving (4 dB below max). The GSM Tx output power is assumed maximum. Transitions between use cases Transitions are not considered yet but kept for future discussions.

7. Company Confidential 7 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Temperature Limits for Different Touching Durations Different use case may have different temperature limits due to the duration of touching. IEC 60950 specifies “short period touching” and “continuous holding”. Short period touching: The phone is touched only for maximum three seconds. It is not necessary to hold the device in the hand to operate it in the intended use case. The related temperature limit is higher than the one for continuously holding. Continuously holding: The phone is held for a long period. It is necessary to hold the device to operate it in the intended use case. This classification is needed to identify the applicable temperature limit for each use case.

8. Company Confidential 8 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Temperature Limits for Different Use Cases The applicable temperature limits for the use cases depend on the duration of touching the device. For the use case “In hand” the limits for “Continuously holding” have to be regarded. For the use cases “Desk top” and “In car”, the limits for “Short period touching” are applicable. The reason is that the device is operated on the desk top or in a car holder and not held in hand. Even when a call is coming in, the keyboard will be touched only shortly. The user will realize if the device is hot and not keep it in his hand.

9. Company Confidential 9 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Thermal Use Case Matrix Template to define and agree on what is definition of worst case thermal scenarios. Refer to Excel table.

10. Company Confidential 10 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Measurement Hints All temperature tests are performed at room temperature and the results are extrapolated to the required ambient temperature by adding the difference. E.g. if you measure at 25°C, you have to add 10°C to the result for the “In Car” use case. All tests have to be performed with similar RF environment: RF connection via antenna. No metal in a distance of 20 cm around the phone. All use cases are performed in free air. The names of the use cases are given only for illustrating the purpose (e.g. “In car” is not measured in a car but in the lab as well.) The Thermal Use Case Matrix only gives an overview and a guideline of the possibly applicable features. The program has to decide which combination of features contributes to the use case. If the worst of the realistic use cases cannot be assessed in advance, several use cases have to be measured.

11. Company Confidential 11 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Extract from IEC 60950

12. Company Confidential 12 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Transition from Short to Continuous Touching IEC 60950 defines “Short period touching” and “Continuous holding”, but does not define the terms “short” and “continuous”. Combining the temperature limits from IEC 60950 (abbreviated as “950”) with the limit lines in EN 60563 (abbreviated as “563”), the graphs on the following pages show the timing constraints for the transition between “short” and “continuous”. The limit graphs in the following pages can be applied as following: Precondition: the initial temperature before touching is above the “Continuous holding” limit but below the “Short period touching” limit. The temperature drop during touching is measured with a thermocoupler. If the temperature falls below the limit for “Continuous holding” and does not exceed the specified limit line, the test is passed. But the initial temperature before touching shall not exceed the higher limit!

13. Company Confidential 13 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Uncoated metal 60 55 3 10 t (s) 0 (C) Short period At 3 s, the limit from 950 hits the 563 graph. Continuous At 10 s, the limit from 950 hits the 563 graph. Limit: the temperature starts at 60°C and drops to 55°C within 10 s due to touching.

14. Company Confidential 14 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Coated metal 60 55 3 10 0 (C) 64 68 70 Short period At 3 s, the limit from 950 hits the 563 graph. 75 t (s) 300µm 150µm 100µm 50µm uncoated Continuous At 10 s, the limit from 950 hits the 563 graph. Coating thickness:

15. Company Confidential 15 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Ceramic, glass and stone 3 10 t (s) 0 (C) 70 65 Short period At 3 s, the limit from 950 hits the 563 graph. Continuous At 10 s, the limit from 950 hits the 563 graph.

16. Company Confidential 16 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS Plastics 75 7 10 t (s) 0 (C) 85 70 2 Short period At 2 s, the limit from 950 hits the 563 graph. Continuous At 7 s, the limit from 950 hits the 563 graph. Remark: The plastic used for Nokia phones housings is ABS plastic with an estimated inertia value of 0.21.

17. Company Confidential 17 © 2005 Nokia Thermal_Requirements_Guideline_v10.ppt / 2006-09-14 / OS RF Output Power for Use Cases GSMWCDMA In HandMax PL4 dB below max PL Desk topMax PL4 dB below max PL In car2 dB below max PL6 dB below max PL Max RF Tx power (Power Level, PL) GSM 850/900: PL 5 (2W) GSM 1800/1900: PL 0 (1W) Class 3: 24 dBm Class 4: 21 dBm