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Afternoon Agenda. Deciding on your soldering equipment and important factors to consider on configuration for a robust process Reflow.
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Afternoon Agenda Deciding on your soldering equipment and important factors to consider on configuration for a robust process Reflow
In general machine created process defects are more to do with original configuration decisions and daily set up understanding rather than actual machine faults
One equipment contributor to reflow defects is the wrong oven size or the wrong number of zones
The wrong size oven leads to incorrect profile for the paste and the product and will lead to defects
Reflow The basic requirement of any Reflow oven is to be able to consistently reflow your product at the required speed to meet production needs Calculation is Process speed = Heated Length (inches) Paste Dwell (minutes)
Example • Reflow system needs to process at 30”/minute with 4minute paste dwell profile Heated Length = 30 x 4= 120”(3M) Not all ovens have same heated length per zone • Note this is NOT total oven length • More zones will allow for greater process controls and zone definitions which allows for tighter profile control
Important factors for consideration • Air or Nitrogen • Flux maintenance • Thermal performance • Power consumption • Cooling capability active or passive • Other factors
Air or Nitrogen • Air systems run invariably cleaner • N2 will widen the process window • Pin in paste type applications may influence need for secondary flux management systems due to flux amounts (GRS)
Global costs • Nitrogen added expense
Flux management Typical GRS System Flux laden gas passes through condensation system and removable filters out side of the tunnel for ease of maintenance
Affect of heater cell designon power consumption and T Efficient design of heater cell increases thermal transfer rates and decreases T Lowers overall cost for energy Can allow for shorter total oven heated length resulting in lower overall cost of ownership
Heater cell design affect on power usage and costs Poor heater cell design results in much higher KW usage and slow reaction to loading which results in slower throughput ability or increased T
Cooling • Cooling rate is a key component on joint integrity and strength • Product density, size and complexity will determine your need • Cooling affects the time above liquidious • Active cooling needs to be considered
Active cooling Passive cooling involves using make up fresh air only and will heat up during the day causing TAL issues Active cooling involves using recirculated liquid and heat exchangers and will maintain down to 50 F Below this temperature an external chiller is needed
Other automatic options assisting process • Automated recipe generation based on PCB typesaving multiple profiling time
To ensure you have a robust process pay attention to the machine configuration and daily set upDon’t ignore the cooling sectionHave the machine automate decisions based on certain criteria