There is a process called “exposure” in the PCB production process. Generally, the CCD semi-automatic exposure machine is used by PCB factories, in addition to CCD, there is also an LDI direct imaging exposure machine.
Compared with the traditional CCD semi-automatic exposure machine, LDI has many advantages. For example, it does not need film, which reduces the film production cost and shortens the sample delivery time. The error of film production and alignment is reduced, and the line exposure is more accurate. In addition to the above advantages, the exposure speed of LDI is slower than that of CCD, so it is more suitable for making samples.
The bottleneck factors of LDI exposure speed include: data storage and transmission, laser energy, switching speed, multilateral production speed, photoresist sensitivity, laser head moving speed, circuit board transmission operation mode, etc.
In terms of basic influencing factors, there are three independent factors that affect the exposure rate:
1. energy density
2. speed of data modulation
3. speed of mechanical mechanism
The modulation switching speed of laser determines the number of light spots that can be drawn per second. Of course, the demand for resolution will affect the production speed. When the resolution is increased by twice, the light spot to be made becomes four times. Therefore, the resolution will have a geometric magnification relationship with the modulation load of the exposure equipment.
The moving speed of the platform will be an influencing factor, especially the acceleration and deceleration mechanism. When the circuit board must move to a new scanning area, the time required for its movement will directly affect the production speed. This concept is similar to the concept of laser drilling machine.
Although the speed of LDI exposure machine is slow, it can not make high-precision lines without it. At the same time, it can reduce the cost of making film for PCB samples and shortens the sample delivery time.
Dec. 23, 2021 
