Many electronics factories think that purchasing a larger reflow soldering machine can meet the general performance requirements, but it usually costs a lot of money and sacrifices the space occupied. 8 to 10 zone reflow and faster belt speeds may be the best solution in a high volume production environment, but our experience has shown that the smaller, simpler, more affordable 4 to 6 zone models are our best A top seller and does an excellent job of handling pick and place throughput, meets solder paste manufacturers’ reflow specifications, and delivers reliable, premium soldering performance. But how can you be sure? How many products can a 4-zone, 5-zone or 6-zone reflow process handle? Some simple calculations based on data provided by solder paste and equipment suppliers will give you a very good reference
Solder paste heating time
The first thing to consider is your solder paste manufacturer’s recommended formulation for the paste formulation you will be using. Solder paste manufacturers typically provide fairly wide window times (in terms of total heating time) for the various stages of the reflow profile – 120 to 240 seconds for preheat and soak time, and 60 to 120 seconds for reflow time/time above liquid state. We’ve found an average total heat time of 4 to 4½ minutes (240-270 seconds) to be a good, relatively conservative estimate. For this simple calculation, we recommend that you ignore the cooling of the welded profiles. Cooling is important, but usually won’t affect soldering quality unless the PCB is cooled too quickly.
Length of heated reflow oven
The next consideration is the total reflow heating time, almost all reflow manufacturers will provide the reflow heating length, sometimes called heating tunnel length, in their specifications. In this simple calculation, we only focus on the reflow area where the heating occurs.
belt speed
For each reflow you are using, divide the heat length (in inches) by the total recommended heat time (in seconds). Then multiply by 60 seconds to get the belt speed in inches per minute. For example, if your solder heat time is 240-270 seconds and you are considering a 6-zone reflow with an 80¾ inch tunnel, divide 80.7 inches by 240 and 270 seconds. Multiplied by 60 seconds, this tells you that you need to set the reflow belt speed between 17.9 inches per minute and 20.2 inches per minute. Once you determine the belt speed you need for the reflow you are considering, you need to determine the maximum number of boards per minute that can be processed in each reflow.
The maximum number of reflow plates per minute
Assuming that at maximum capacity you have to load boards end-to-end on the reflow oven’s conveyor, it’s easy to calculate the maximum yield. For example, if your board is 7 inches long and the belt speed of a 6-zone reflow oven ranges from 17.9 inches to 20.2 inches per minute, the maximum throughput for that reflow is 2.6 to 2.9 boards per minute. That is to say, the upper and lower circuit boards will be soldered in about 20 seconds.
Which Reflow Oven is Best for Your Needs
In addition to the above factors, there are many other factors to consider. For example, double-sided production may require reflowing both sides of the same component, and manual assembly operations can also affect how much reflow capacity is really needed. If your SMT assembly is very fast, but other processes are limiting your factory’s throughput, then the world’s largest reflow is not so good for you. Another factor to consider is the changeover time from one product to another. How long does it take for the reflow temperature to stabilize when changing from one configuration to another? There are many different things to consider.
Chengyuan Industry has been focusing on reflow soldering, wave soldering, and coating machines for more than ten years. Welcome to contact Chengyuan engineers to choose the most suitable reflow soldering for you.
Post time: May-15-2023