R&D Technical Services
R&D Technical Services was formed in 1996 to support the Vapor Reflow market and is currently the leading source of Vapor Phase equipment
R&D Vapor Phase machines are being used everyday in a wide variety of markets such as, but not limited to: SMT Solder Reflows, Lead Free Soldering, Curing, Drying, Mechanical Attachment and Plastic Package Testing.
Vapor Phase is the leader in Safe, Repeatable Heat Transfer
with advantages such as:
WHAT IS VAPOR PHASE SOLDERING??
Vapor Phase or Condensation Heating has been around for many years in many different variations. It uses an inert liquid that when heated, creates a very stable uniform heat transfer medium in the form of vapor. This heat transfer medium replaces heat energy very quickly. It transfers heat to the product by condensing this heated vapor to the product with little regard to mass. Another property of vapor phase is the maximum temperature at reflow. The maximum temperature is tied to the boiling point of the fluid. This means vapor phase won't damage parts with overheating. The condensation effect of the vapor also allows the vapor to transfer heat to all surfaces of a product evenly without the effects of "shadowing", "deflection", or "reflection" . These facts combine to make vapor phase soldering one of the most solid and repeatable reflow and heat transfer processes.
The earliest units used simple methods to heat the liquid which created the vapor. Later, preheat was added as a process enhancement. This first type of preheat generally utilized a secondary vapor with a lower fixed temperature. The product was first lowered on an elevator system into the preheat or "secondary" vapor which hovered above the primary vapor. After a certain temp was attained in the secondary vapor, the product was then lowered into the "primary" vapor for reflow. Cooling coils have generally been used as the containment apparatus for the vapor blanket. As the generated vapor is much heavier than air, it remains in the bottom of the tank. The cooling coils then condense any excess vapor to maintain a set height of the vapor blanket. Condensed fluid returns to the boiling liquid.
Current design of most vapor phase units have removed the "secondary" vapor in favor of an IR or Convected type of preheat. This design change took place to provide better control of the preheat thermal curve, as well as to remove the secondary vapor from the process. This secondary vapor was often Freon in the early days and was discovered to cause ozone depletion.
The vapor blanket or the layer of saturated vapor within the machine is at an even temperature throughout. There are no side to center or front to back variations in the vapor blanket temperature. Large mass differentials on the board itself are of little consequence to the process because they extend the reflow time only slightly. Small parts will reflow somewhat sooner than large parts, but it has been found that for reflow times of up to a minute, extremely large mass differentials can be handled. This is due to the large reservoir of heat available and relatively rapid heating capabilities of condensation heating. This process is so stable that a minimum amount of thermal profiling is required.
Most vapor phase units utilize some sort of conveyor system to transport the product to be heated though the critical stages of the oven: Preheat, Reflow, Flash Off, and Cooldown. You can generally find these ovens in either "Batch" type or "Inline" type, they can use palletized conveyors, belted conveyors, transport system conveyors, or a mix of several types. We now have a process that takes the board or assembly through a nearly ideal reflow curve. This process or more appropriately, this combination of processes provides for stability and uniformity and yet is extremely flexible and cost effective, while maintaining the highest quality and reliability.