Some PCB circuit boards are often designed in an imposition manner because they are relatively small, which not only facilitates the processing and production of the PCB manufacturer but also reduces the waste of the board and reduces the cost. In order to facilitate the manufacture of the circuit board and printed circuit board assembly processing, many problems need to be paid attention to when designing the PCB imposition.

Precautions for PCB imposition design In order to facilitate production, PCB circuit board imposition generally needs to design Mark points, V-grooves, and process edges.

The shape of the imposition

1. The outer frame (clamping edge) of the PCB is to be closed-looped to ensure that the PCB is not deformed after it is fixed on the fixture.

2. PCB board width ≤ 260mm (SIEMENS line) or ≤ 300mm (FUJI line); if you need automatic dispensing, PCB board width × length ≤ 125 mm × 180 mm.

3,.PCB layout as close to the square as possible, it is recommended to use 2 × 2, 3 × 3, ... puzzle.

V-shaped groove

1. after opening the V-shaped groove, the remaining thickness X should be (1/4 to 1/3) plate thickness L, but the minimum thickness X must be ≥ 0.4 mm. The upper limit of the board with heavier load can be taken, and the lower limit can be taken for the board with lighter load.

2. The misalignment S of the upper and lower sides of the V-shaped groove should be less than 0.1mm; due to the limitation of the minimum effective thickness, the V-grooved plate method should not be adopted for the plate with the thickness less than 1.2mm.

Mark point

1. when setting the reference positioning point, usually leave a non-resistive soldering area 1.5 mm larger than the positioning point.

2. used to help the optical positioning of the placement machine with the chip device diagonally at least two asymmetric reference points, the entire PCB optical positioning reference point is generally in the corresponding position of the entire PCB diagonal; block PCB The reference point for optical positioning is generally at the corresponding position of the diagonal PCB circuit board.

3. For QFP (square flat package) with lead pitch ≤0.5mm and BGA (ball grid array package) with ball pitch ≤0.8mm, in order to improve the placement accuracy, it is required to set the reference point at two diagonals of the IC.

There should be no large devices or protruding devices near the connection point between the outer frame of the panel and the inner small plate, the small plate and the small plate, and the edges of the components and the PCB circuit board should be larger than 0.5mm space to ensure the normal operation of the cutting tool.

On-board positioning hole

1. The whole board positioning for PCB circuit board and the reference symbol for fine-pitch device positioning. In principle, QFP with spacing less than 0.65mm should be set at its diagonal position; used for imposition PCB The positioning reference symbols of the plates should be used in pairs and placed at opposite corners of the positioning elements.

2. large components should be left with positioning posts or positioning holes, such as I / O interface, microphone, battery interface, micro switch, headphone interface, motor and so on. A good PCB designer should consider the factors of production when making imposition design, so as to facilitate processing, improve production efficiency and reduce production cost.