Profile the easy way..

Transcription

1 Profile the easy way..

2 The need for continuous monitoring The classical way to obtain a temperature profile is to attach thermocouple sensors to the PCB and record the temperature profile using a heat protected data logger which travels through the process behind a test PCB. This method works very well for initial machine setup it does not lend itself to ongoing process monitoring in high production rate environments as it can only be deployed periodically. Manufacturers are therefore faced with the less than ideal situation of having to manually snapshot the process every few hours and assume that in between the process remains good. Each time a process snapshot is taken, production must be stopped to allow the test board and profiler to pass through. If a problem does occur, it will only be discovered the next time a process snapshot is taken, and under the worst case this could involve several hours of production. What is required is a simple automatic system which can remove the need to profile with test boards during production.

3 What is Virtual PCB Profiling? SOLDERSTAR APS Virtual PCB Profiling Traditionally a profiling instrument is used to establish the correct thermal profiling for the soldering process. Thermocouples are attached to a real PCB, and the component level temperatures are captured by the measurement datalogger. Verification profiles are then captured on the SMT line by periodically passing the test PCB and instrument through the process. If we wish to ensure that the thermal profile is correct for 100% of all PCB s manufactured the APS 2000 system is employed. The APS 2000 continuously tracks PCB movements through the machine and also monitors process fluctuations at products level. These changes are then used by a mathematical model to calculate what the resulting PCB profile would be, this is known as the virtual profile. Process parameters can then be calculated and tested within limits

4 Virtual PCB Profiling ( continued ) SOLDERSTAR APS Virtual PCB Profiling The following steps are performed to all the APS 2000 to calculate profiles in real-time. Step 1: We capture the actual profile from a PCB using a Solderstar Profiler (This gives the software the thermal model of the oven & the components/pcb) Step 2: The APS 2000 analyses and records the good state of the reflow oven Step 3: The APS 2000 now measures in real-time any fluctuations in the process, the information from Steps 1&2 is used to calculate the resulting profile. Process parameters are calculated and tested against defined limits.

5 Virtual PCB Profiling ( continued ) SOLDERSTAR APS Virtual PCB Profiling Capture the actual profile from a PCB using a Solderstar Profiler The APS 2000 analyses and records the good state of the reflow oven Real-time profile Product level temperatures are measure along with conveyor speed Original PCB Profile

6 How the system works The SolderStar APS is a full time reflow process monitoring system designed for convection reflow ovens. The system works by continuously measuring product level zone temperatures and conveyor speed and comparing these measurements to a captured process reference which the system has previously learned. The system continuously compares each new set of measurements with the reference and evaluates any differences. Should the difference between the current process and the reference exceed user defined limits, then further boards are prevented from entering the oven by way of the oven SMEMA interface. The user is then alerted in order for corrective action to be taken Full live statistics and process Cpk are produced automatically. Speed and temperature measurements are stored in a database for each PCB travelling through the soldering process for full product traceability.

7 Why measure independently of the oven? The APS system measures the product level zone temperatures and conveyor speed independently of the oven. This is important for two reasons:- Firstly the machine may malfunction for example a heater or fan may give trouble. Secondly, an operator may load the wrong recipe for the board being produced. Why measure temperature at Product Level? The oven itself monitors and maintains the temperature of each zone. This measurement is made near to the heaters and does not closely reflect the temperature seen at product level which is a function of the machine convection. The APS system adds independent temperature sensors mounted at product level close to the conveyor rails. These sensors are designed to closely measure the heating levels impinging on passing circuit boards whilst at the same time minimizing shadowing caused by the sensor itself.

8 The APS system is configured as follows:- Dual Rail Monitoring System The Dual Rail Monitoring configuration uses temperature probes to measure at product level on both the left and right side of the conveyor. Probes are custom made for each oven with sensors positioned centrally within each zone. Probe A Probe B Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone N

9 Process Reference The process reference is captured prior to production starting and when the process has already been setup and confirmed to be correct using classical profiling techniques and a test board. During this phase the oven SMEMA interface is asserted which prevents loading of boards into the oven. As part of the Reference Teach, the user must set process WARN and STOP limits that are to be enforced by the APS system during production. These limits allow upper and lower thresholds for each of the product level temperatures and the conveyor speed to be specified. They dictate how far away from the reference the process will be allowed to drift before production is stopped.

10 Process Monitoring Once the Reference has been learned and limits set for the process, the APS system can start monitor the process. As a PCB enterer the reflow oven, its progress is tracked through and temperatures recorded at product level sensor as the PCB goes through the zone. When the PCB exits the oven, the profile is mathematically calculated using the live measurements, and the PCB reference profile, it is then evaluated PASS/FAIL and recorded. For each PCB we have a record of the process speed, and each zone temperature and the mathematical profile.

11 Software Overview: APS Central, intuitive and simple to use. Process Window Checkers Navigator Bar The navigator bar provides instant shortcuts to each feature of the software. Active Profile Process History

12 Software Overview : Process History A complete record of the activity per PCB within your reflow process Process List Production Batches Process Result History Process Events

13 Software Overview : Zone Checker window The zone checker window is a live update window when the APS is running which shows measured oven parameters plotted against the process user limits for the Process. Parameter Limit Bands Process Warn Parameter Value at Reference Process OK Process Stop The green area represents a parameter which is inside the WARN limits and represents a normal process. The amber area represents a parameter which is within the STOP limits but outside the WARN limits. The red area represents a parameter outside the process STOP limits.

14 Software Overview : Process Checker window The process checker window is a live update window which shows the live process parameters calculated from the current calculated virtual profile. Warning and Stop levels can be configured for Peak Temperature, Time above and soak time. Process Limits

15 Software Overview : Oven Data Window The oven performance data window shows live readings from the APS system along with reference and set-point values when the APS system is running. Heater set points Conveyor Speed Values Measured Values Left & Right Reference Values Left & Right

16 Easy to understand system concept PROCESS TEACH then TEST Simple to fit and operate The APS System Advantages Full time monitoring of reflow soldering process which does not rely on repeated profiling. User Process limits allow the machine to be automatically stopped if the process drifts too far away from the reference. Automatic process tracking and traceability for all products produced.

17 About SolderStar SolderStar is a specialist in the design, development and manufacture of specialist thermal profiling equipment for the lead-free electronics industry. Incorporating state-of-the-art technology and full lead-free compliance, SolderStar s range of instruments and software tools offers leading-edge performance, functionality, heat-resistance and miniaturization. SolderStar satisfies all of today s thermal process control needs, from full-feature high performance product profiling for reflow and wave solder processes, to fully integrated SPC capabilities for continuous quality and process control. Products are available individually or in packages that are tailor-made to suit the technical and budgetary requirements of all electronics manufacturers, whatever their size and needs and wherever they are in the world. For more information about SolderStar, visit the company s website at.