# What is thermal resistance junction-to-case?

## What is thermal resistance junction-to-case?

Junction-to-case thermal resistance (θJC) is defined as the thermal resistance from the semiconductor junction to the case of the oscillator (junction-to-case). A low value of θJC corresponds to increased heat conduction and a high value corresponds with decreased heat conduction.

## How do you find the junction-to-case thermal resistance?

1. P = Total Device Power Dissipation (W)
2. T = Temperature (°C)
3. ΔT = Temperature Differential = P × θ
4. θJA = Junction-Ambient Thermal Resistance.
5. θJC = Junction-Case Thermal Resistance.
6. θCA = Case-Ambient Thermal Resistance.
7. θJA = θJC + θCA.
8. TJ = TA + (P × θJA)

What is thermal junction?

From Wikipedia, the free encyclopedia. Junction temperature, short for transistor junction temperature, is the highest operating temperature of the actual semiconductor in an electronic device. In operation, it is higher than case temperature and the temperature of the part’s exterior.

What is the use of thermal resistance?

Thermal Resistance (R-Value) Thermal resistance is the temperature difference, at steady state, between two defined surfaces of a material or construction that induces a unit heat flow rate through a unit area, K⋅m2/W.

### What should my GPU junction temp be?

While ideal GPU temperatures are usually between 65° to 85° Celsius (149° to 185° F) under load, AMD GPUs (like the Radeon RX 5700 or 6000 Series) can safely reach temperatures as high as 110 degrees Celsius (230° F).

### How do you calculate heatsink thermal resistance?

Thermal Circuit

1. R = T/Q.
2. Were T is the temperature difference between the two locations.
3. Re = V/I.
4. With V being the voltage difference and I the current.
5. Figure 1: Thermal resistance circuit.
6. Rcs = ( Tcs)/Q = (Tc– Ts)/Q.
7. Rsa = ( Tsa)/Q = (Ts– Ta)/Q.
8. Figure 2: Cost versus required thermal resistance.

What is a good PC case temperature?

Your CPU shouldn’t go above 50 C. My case runs at about 40-45 C ambient. Most CPUs should run at 50 C or less during full load. If your case is too hot, then the air inside will be too hot to dissipate the heat.

How is the junction to case thermal resistance calculated?

The junction-to-case thermal resistance, Θ JC, is calculated using the following equation, which has the same form as Ohms Law for electrical resistances:

#### How to predict junction temperature with heat sink?

The analysis begins with a consideration of how to predict the junction temperature in a package with a heat sink attached to it, based on 1) thermal measurements on the package/board assembly in a wind tunnel and 2) thermal measurements made on the heat sink by its manufacturer.

#### What is the thermal resistance of a heat sink?

If there is a heat sink present, then the heat flow through the heat sink into the air is represented by the sink-to-air thermal resistance, ΘSA. The downward flow of heat from the chip is represented by the two thermal resistances: junction-to-board, ΘJB, and the board-to-air, ΘBA.

Is there an upper limit for junction temperature?

For reliability reasons, integrated circuits handling appreciable power are increasingly called upon to observe thermal management. All semiconductors have some specified safe upper limit for junction temperature (TJ), usually on the order of 150°C (sometimes 175°C).