With a hot plate (a direct contact device), it is nearly impossible to achieve three discrete stages with any degree of accuracy, so this technique is recommended only for the hobbyist who makes a couple boards a day and isn’t particular about the thermal profile. Depending on the material, e.g., leaded, lead-free or specialty materials such as epoxies, the heating profile for each stage will vary according to the manufacturer’s specifications to achieve optimal bonding. After this, the board is typically cooled and removed. A typical soldering operation in today’s world requires three main stages for temperature profiling: Preheat, Soak, and Reflow to perform these functions: 1) The preheat stage for a certain period of time to activation temperature, 2) the soak stage for a different period of time to activate the solder, and 3) the reflow stage where temperatures peak for yet a different time frame. **In a typical low-to mid-volume production world, a small conveyorized horizontal convection oven meets most basic requirements. # of zones dependent on speed & target volume The following is a guideline for zones relating to typical volume needs: Board Throughput There are other considerations too, such as board size, component density, and appropriate thermal technology, but we’ll talk about those after identifying the work flow volume. The decision has to be qualified primarily on your anticipated throughput, that is, how many boards you process in a day or a week. As with any complex process, there will be tradeoffs between cost and capabilities, and more zones will always give you better flexibility and more control over your profile, but at a cost. Seems like an odd way to start a discussion about Reflow Ovens, but it’s not entirely unreasonable.

Vapor Phase: Vapor is generated by heating a fluid with a specific boiling point (240° C) and transfers heat to the circuit board just above the melting point of the solder.

Infrared (IR): Boards are passed inside a chamber over a direct IR heat source.Convection: Boards with their assembled components are passed through heated, circulating air from a conventional electrical heat source.

The other heating methods are typically performed within a chamber (oven) but rely on different heating methods: There are several different reflow methods to liquefy solder in a controlled way and not all of them can literally be called “ovens”.įor instance, the simplest form of heating is performed by conduction, that is, by contact with a heated surface such as a hot plate.

Vapor phase reflow