Introduction
This document outlines the recommended parameters for the Wave Soldering process applied to electronic boards assembled with lead‑free alloys, particularly SAC (Sn‑Ag‑Cu).
The values provided serve as reference guidelines to support process setup and optimization; however, they must always be adapted to the specific operating conditions of the equipment, the flux used, and the characteristics of the PCB.
Wave soldering is influenced by numerous variables — including printed circuit board design, flux chemistry, component geometry, machine configuration, and thermal profile. For this reason, the parameters described here should be considered general indications and must be verified and validated by the process owner in accordance with material manufacturers’ recommendations and actual production conditions.
Flux to Be Used
Any flux type may be employed; however, the use of an activated or moderately activated high‑performance No‑Clean flux is recommended. Both alcohol‑based and water‑based (VOC‑free) formulations are suitable.
Board Pre‑Heating: Time and Temperature
Pre‑heating conditions are closely linked to the flux type.
For water‑based fluxes, the temperature measured on the bottom side of the PCB may theoretically range from 120 °C to 200 °C, with pre‑heating times typically between 60 and 180 seconds.
In practice, the optimal pre‑heating profile must follow the flux manufacturer’s specifications, while the PCB manufacturer defines the maximum allowable temperatures for the board material.
Ramp‑Up Rate
A maximum ramp‑up rate of 3 °C/s is recommended.
Solder Bath Temperature
For SAC (Sn‑Ag‑Cu) and similar lead‑free alloys, the solder bath temperature for single‑sided PCBs generally falls within the range of 250 °C to 260 °C.
Soldering Time
For lead‑free alloys, the recommended contact time with the solder wave is typically 3 to 6 seconds.
Ramp‑Down Rate
A maximum ramp‑down rate of 6 °C/s is suggested.
IMPORTANT
The parameters above are intentionally general and should be interpreted as academic guidelines. The wave soldering process is governed by multiple interdependent factors, all of which contribute to the final soldering quality.
Therefore, the selection of the PCB material, the flux type, and the overall duration of the soldering cycle are all critical elements that must be carefully evaluated to ensure a reliable and robust soldering process.
