What’s new in RKC Instrument Controllers..
One of the product released from RKC Instruments is the PF900 and PF901 Ramp/Soak Controllers.
What is a Ramp Soak Controller
Ramp Soak Controllers are subset of Profile Controllers. These are mainly used for controlling temperature or any other process parameter against time. Ramp soak controllers control the rate of rise (ramp) of temperature / controlled parameter and then maintain it to the programmed value for programmed time.
Ramp is defined as the rate of change in temperature over time, expressed in degrees per second. The most commonly used process limit is 4 °C/s, though many component and solder paste manufacturers specify the value as 2 °C/s. Many components have a specification where the rise in temperature should not exceed a specified temperature per second, such as 2 °C/s. Rapid evaporation of the flux contained in the solder paste can lead to defects, such as lead lift, tombstoning, and solder balls. Additionally, rapid heat can lead to steam generation within the component if the moisture content is high, resulting in the formation of microcracks.
In the soak segment of the profile, the solder paste approaches a phase change. The amount of energy introduced to both the component and the PCB approaches equilibrium. In this stage, most of the flux evaporates out of the solder paste. The duration of the soak varies for different pastes. The mass of the PCB is another factor that must be considered for the soak duration. An over-rapid heat transfer can cause solder splattering and the production of solder balls, bridging and other defects. If the heat transfer is too slow, the flux concentration may remain high and result in cold solder joints, voids and incomplete reflow. After the soak segment, the profile enters the ramp-to-peak segment of the profile, which is a given temperature range and time exceeding the melting temperature of the alloy. Successful profiles range in temperature up to 30 °C higher than liquidus which is approximately 183 °C for eutectic and approximately 217 °C for lead-free.
The final area of this profile is the cooling section. A typical specification for the cool down is usually less than −6 °C/s (falling slope).
The Ramp to Spike (RTS) profile is almost a linear graph, starting at the entrance of the process and ending at the peak segment, with a greater Δt (change in temperature) in the cooling segment. While the Ramp-Soak-Spike (RSS) allows for about 4 °C/s, the requirements of the RTS is about 1–2 °C/s. These values depend on the solder paste specifications. The RTS soak period is part of the ramp and is not as easily distinguishable as in RSS. The soak is controlled primarily by the conveyor speed. The peak of the RTS profile is the endpoint of the linear ramp to the peak segment of the profile. The same considerations about defects in an RSS profile also apply to an RTS profile.
When the PCB enters the cooling segment, the negative slope generally is steeper than the rising slope.
What features do RKC Instrument Controllers PF900/PF901 have
Features: The program controllers has the following features: Selectable LCD color Dominant color (s) of LCD is selectable when ordering. • PF900: Green and Orange• PF901: White Easy-to-read display. Easily check the operation state in progress by the simultaneous display of segment level and segment time, the operation lamps, and the program pattern indicated with the bar graph of dots. Large-capacity program setting Up to 99 program patterns may be set. Each program pattern offers up to 99 segments. 1024 segments maximum: number of Pattern × number of segment Auto tuning (AT) with learning function Search soak areas to conduct Auto tuning (AT) to the segments in turn in the Reset mode (RESET). Display Function Selectable Sampling cycle It is possible to switch Sampling cycle between 50 ms, 100 ms and 250 ms. Program pattern copy function Easily create new program pattern by copying patterns or segments being programmed. Set values management Setting the Memory group of each segment where set values such as PID values and Event are stored may allow specific control for each segment.Parameter setting groups• PID memory group: 8 groups • Event memory group: 8 groups • Wait memory group: 8 groups • Time signal memory group: 16 groups • Output program memory group: 1 to (128/Maximum segment number) Selectable PID zones Level PID and Segment PID may be changed. Ramp/Soak stabilizer function Suppress overshoot when the program shifts from ramp to soak.
The RKC PF900 / PF901 are high performance ramp/soak controller have High intensity display. New control algorithm RSS (Ramp Soak Stabilizer). Maximum of 3 point program pattern outputs.Up to 1024 segments. Two types signal mode (Time signal output, Segment signal output). Satisfies versatile applications.Memory group. Collaborative program operation (Inter-controller communication). Front loader interface + Programming tool.