Selecting suitable reflow soldering equipment requires evaluating several factors. The key points are as follows.
Conveyor Belt Width
The conveyor width should be selected according to the largest PCB size to be processed. For example, if the maximum PCB width is 200 mm, a mesh belt width of 300 mm is appropriate. Common mesh belt widths include 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, and 600 mm.
Choosing a wider conveyor is not always better. A larger width usually means higher power consumption, so the width should match actual production requirements to avoid unnecessary energy use. For non-standard conveyor rails or custom guide components needed to accommodate special board sizes, Hansheng Automation can provide custom-machined parts based on customer drawings.
Solder Paste Heating Time
The reflow oven temperature profile should follow the solder paste manufacturer's specifications. Paste manufacturers typically provide wide process windows for each stage of the reflow profile. Preheat and soak time is generally 120 to 240 seconds, and reflow time above liquidus is 60 to 120 seconds.
A total heating time of 240 to 270 seconds is a relatively conservative and practical estimate. In simple calculations, the cooling stage can often be ignored because cooling mainly affects soldering quality only when the PCB cools too quickly.
Heating Zone Length and Number of Zones
Longer heating zones and a greater number of zones make it easier to adjust and control the temperature profile. For small and medium batch production, a reflow oven with 5 to 6 zones and a total heated length of about 1.8 m is usually sufficient.
Upper and lower heaters should have independent temperature control so the profile can be adjusted according to actual soldering conditions and quality requirements.
Maximum Throughput of Boards
The maximum throughput can be estimated by loading boards end to end on the conveyor at maximum capacity. For example, if the board length is 7 inches and a 6-zone reflow oven has a belt speed range of 17.9 to 20.2 inches per minute, the maximum throughput is approximately 2.6 to 2.9 boards per minute, meaning one board is soldered about every 20 seconds.
Other Factors
Double-sided boards require two soldering passes, which places higher demands on temperature control accuracy and equipment stability. Manual assembly operations may also affect board positioning and soldering consistency.
Equipment selection should also consider the factory's available space, budget, and the output of other processes. If floor space is limited, a smaller machine with a compact footprint may be needed. If upstream processes have high output, the reflow oven must provide matching capacity and performance.
