PCB Technical - PCB circuit board can be directly wave soldered

Under what conditions can the PCBA board be directly wave soldered without the need for a carrier? In fact, in the early days of PCBA assembly circuit boards, there was almost no such thing as a carrier. At that time, almost all PCBs were directly subjected to wave soldering without using any carrier, unless the circuit board could not bear too much weight. Load, such as a board such as a power supply board.

PCB circuit board

Furnace carrier is because of the prevalence of selective wave soldering, coupled with the thinner and smaller circuit board thickness and smaller size, there are gradually a large number of applications of furnace carrier appear. Therefore, not all wave soldering processes necessarily require a furnace carrier.

Then under what circumstances can the PCB go through the wave soldering furnace without going through the furnace carrier? Below I list some of its requirements

PCB design requirements:

At least 5mm or more of the side of the PCB should be reserved for the wave soldering chain (gripper) and the support when the PCBA is placed in the magazine.

The thickness of the PCB should preferably be 1.6mm or more, so that the problems of warpage and overflow will not occur during the furnace.

It is recommended that the gap distance of all solder pads should be above 1.0mm to avoid short circuit between solder joints.

Parts and layout requirements:

The type of SMD parts and the direction of SMD parts must meet the requirements of wave soldering. (Generally speaking, SMD parts need to be perpendicular to the direction of travel of the board)

The wave soldering surface of the circuit board only allows SMD parts, SOT, SOP, QFP... and other parts above 0603 (inclusive) size, and other parts such as BGA, PLCC, QFN, connectors, transformers, 0402 (inclusive) sizes below Parts cannot be placed on the wave front welding surface.

The plug-in parts must all be designed on the first side and the direction of the plug-in parts must meet the requirements of wave soldering. (The row pin must be parallel to the direction of travel of the board)

The parts on the PCB should not be too heavy to avoid bending the circuit board due to gravity.

Process requirements:

All SMD parts on the wave front soldering surface must be dotted with red glue to avoid falling into the wave soldering furnace.

Some solder pads that cannot be wetted (such as button contact lines, gold fingers) are not recommended to be designed on the wave solder contact surface (the second side).

A small number of solder pads that cannot be wetted with tin can be designed on the contact surface of the tin furnace, but high temperature tape without residual glue must be used for wave front soldering. After completion, the tape must be removed. Try not to design this way to reduce labor hours (labor )

All plug-in parts are recommended to use short-foot operation and wave soldering to avoid short-circuit problems. It is recommended that the length of the parts should not exceed 2.54mm.

The above is about under what conditions the PCB circuit board can be directly wave soldered without loading