Introduction
To check if the SelectX™ can be used it is recommended to make a thermal profile of the joint(s) involved. The example given below is a real measurement on a joint, to investigate the possibility for SelectX™ application. It is a copy of figure 9.7 from the SelectX™ user’s manual.
Example of a typical wave soldering cooling curve using eutectic tin-lead solder. In this example the solder drops in 2.4 seconds from wave soldering to solder solidification temperature. The joint is completely solidified after 4.8 seconds. The time span for debridging this joint is 1.7 seconds. If the SelectX™ can be used depends on the effective nozzle length (green area in the figure). But also on the process settings (conveyor speed) that will affect the time frame that is available for the activation of the SelectX™ on the position of the joint(s) to be treated. With the use of lead-free solder alloys, the effective nozzle length might become too short to apply the SelectX™ successfully. This is due to the smaller band between solder melting point and soldering temperature. For tin-lead solders this band has a span of 250° - 183° = 67°C.For lead-free solders this span is often limited to 260° - 217° = 43°C, or even to 265° - 227° = 38°C, depending of the melting point of the alloy and the process temperature.