SMT machines have strict requirements for the size of PCB to ensure the accuracy of placement and production efficiency. The following are some main size requirements:
1. Size restrictions for panel assembly
Generally speaking, the width of a PCB panel should be less than or equal to 660mm*1100mm.
2. Panel shape design
When designing the panel, the shape should be designed as a square or a rectangle close to a square as much as possible to improve the utilization rate of the panel and processing efficiency.
3. Panel frame design
The outer frame (process edge) of the circuit board after assembly should adopt a closed-loop design to ensure that no deformation occurs after the PCB assembly is fixed on the fixture.
4. Small board spacing and positioning
The center distance between the small plates should be controlled between 75mm and 145mm to ensure the convenience of processing and assembly.
Each small board should be equipped with three or more positioning holes, with hole diameters ranging from 3mm to 6mm. No wiring or SMT mounting is allowed within 1mm of the edge positioning holes.
5. Mark point design
The Mark point is a key positioning reference in SMT assembly processing, and there are strict requirements for its shape, size, position and surrounding environment. Mark points are usually standard circular, square or triangular in size, ranging from 0.8mm to 1.5mm, to ensure the rapid and accurate capture of the visual recognition system.
6. Other requirements
Four positioning holes should be drilled at the four corners of the panel outer frame. The hole diameters are generally taken as 4mm±0.01mm. The strength of the holes should be appropriate to ensure that no adverse phenomena such as breakage occur during the SMT assembly process.
The overall size of the PCB is usually between 50mm×50mm and 660mm×1100mm within the range that SMT equipment can handle.
The bending and deformation of PCB can seriously affect the quality of SMT assembly processing, so the degree of bending and twisting must be strictly controlled.
