BGA's ramp up rate in a convection oven

I am testing some BGA's (PBGA 30mm x 30mm) to evaluate the maximum ramp rate we can achieve in our reflow oven. Temperature is being measured at the body(top) of the component / not leads. After several trials (with various oven settings), the highest ramp rate I am able to measure is 1.4 deg C/second. This is measured when the initial package temp. is 180 C and the final package temp is 210 C. At lower package temperatures (ie. 80C - 100C ) the ramp rate is higher - approx. 3 degC /second. This is achievable with the most aggressive setting in my reflow oven . . . when the component enters the oven, first zone is 275 C, and the remaining 3 zones are set at 300 C. Essentially, the component enters at room temperature and stays in an atmosphere of 275-300 C.

The BGA is placed on a small carrier (1x1 made of std. fr4 material, .063" thick) thus there is virtually no thermal mass. Are my results (ramp rates) typical? What kind of ramp rates can you reach in your oven? My first inclination is to blame the oven, on the other hand what's the difference what oven I am using. If the part enters a 275 C zone (air temperature) in oven A, and 275 C in oven B (air temp.) the ramp rate should be dictated by the absorbtion rate of the part. Logical? Maybe I should try to increase the zone temperatures to say 350 C (probably the limit on my oven).

Thanks

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