The Ramp to Spike Profile is, more or less, a linear graph, starting at the entrance of the process and ending at the peak segment, with a greater Δ t in the cooling segment. In general terms, the RTS profile is a long, slow ramp to the peak temperature, with a rapid cool down in comparison to the initial ramp. Setting your oven’s set points and conveyor speed can be much easier when the characteristics of the oven and profile are well understood.
Similar to the RSS profile, the beginning of the profile is the slope of the ramp from ambient temperature through the first heating zone. The slope is not as steep as for the RSS profile. While the RSS allows for ~4°C/sec, the requirements of the RTS is ~1-2°C/sec. Again, this is dependent on the solder paste specification and you need to double check your component’s spec.
The RTS soak period is part of the ramp and is not as easily distinguishable as in the case of the RSS. The soak is controlled primarily by the conveyor speed settings.
The peak of the RTS profile is the endpoint of the linear ramp to the peak segment of the profile. The same considerations that lead to defects in an RSS profile apply to an RTS profile.
When the PCB enters the cooling segment, the negative slope is generally steeper than the rising slope.