**Precautions for Selective Wave Soldering Carrier and Circuit Board Design:**

1. When the solder pins of traditional plug-ins are too close to the edge of the carrier, solder insufficiency is likely to occur due to the shadow effect.

2. The carrier must effectively cover areas that do not require soldering with the tin furnace.

3. It is advisable to maintain a minimum wall thickness of 0.05” (1.27mm) at the edge of the carrier holes to prevent solder from penetrating areas not intended for soldering.

4. For components that need to be soldered by the tin furnace, keeping at least 0.1” (2.54mm) away from the edge of the carrier holes is recommended to minimize potential shadow effects.

5. The height of components passing through the furnace surface should be less than 0.15” (3.8mm); otherwise, the furnace carrier will be unable to cover these taller components.

6. The material of the soldering furnace carrier must not react with solder, must withstand repeated high-temperature cycles without deforming, be resistant to heat absorption, and be as lightweight as possible with minimal heat shrinkage. Currently, aluminum alloy is commonly used, along with synthetic stone materials.

7. Initially, almost all PCB boards were designed using traditional insertion methods and required wave soldering. At that time, boards were typically single-sided. Subsequently, SMT (Surface Mount Technology) processing was introduced.

8. With the advent of processing technology, the mixed use of PCBA patch processing and wave soldering became common, as many components could not yet be converted to SMT. This means numerous traditional plug-in components were still in use.

9. Therefore, during board design, all plug-in components must be arranged on one side, while the opposite side is designated for wave soldering. Additionally, PCBA patch processing components on the wave soldering side must be secured with red glue to prevent them from falling into the tin furnace during processing.

10. Nowadays, almost all boards have adopted dual-side PCB processing; however, very few components remain that cannot be fully processed using the PCBA patch processing method. Consequently, the selective wave soldering process has emerged to meet these needs.

—

Let me know if you need further adjustments!