Request for RθJC and RθJB (MAX4003EUA) for Thermal Simulation

I cannot find a specification for the thermal resistance for this part. But I think that the thermal resistance value is not very important because the device consumes so little energy. Power consumption is 30 mW worst case. Because the package does not have a heat slug on its underside, I'm going to assume that the junction to board thermal resistance is quite high. Let's say 200 degC/W for junction to case. This means that the temperature difference from junction to board will be only 6 degrees. So if the board is at 85 degC, the die will be at 86 degrees, well under the abs max ratings limit of 150 degC. The junction to air thermal resistance is also probably in the 200 degC/W range. So if air temperature is 85 degC, the die rise is probably going to be at most 10 degrees higher. So while I cannot give you a number, like I said, I don't think that it matters. If you absolutely need a number, I would use 300 degC/W for junction to case and junction to board. Even with this very conservative number, the temperature rise to the die will be quite small because of the low power consumption.