The accuracy of plate copying depends on two aspects, one is the accuracy of software, the other is the accuracy of original image.
As for the accuracy of software, there is no limit to the accuracy of 32-bit floating-point representation, so the most important thing is the accuracy of the original scanned image. For example, if you take a picture with 1 million pixels, you can develop a 5-inch picture, but if you want to develop it into a 20 inch picture, you can’t see clearly at all. The reason is the same, so for a picture with high accuracy requirements Road board, in order to copy a very high precision PCB, in the scanning, it is necessary to choose a higher DPI.
What DPI means is how many dots per inch. That is to say, the distance between every two points on the scanned image is 1000 / DPI, in mil
If DPI is 400, then the distance between two points on the image is 1000 / 400 = 2.5 mil, that is to say, the accuracy is 2.5 mil
This is the most scientific basis, so some people say that the accuracy can reach less than 1mil, which is based on the premise. In fact, the accuracy of plate reading mainly depends on the original scanning accuracy.
To sum up, when scanning the board, the DPI should be set according to the accuracy required by the actual board. If the accuracy requirements such as the line spacing of mobile phone board are less than 1mil, the DPI should be set above 1000dpi. At present, scanners on the market can meet this condition.
The higher the DPI is, the clearer the picture will be and the higher the precision will be. However, the disadvantage is that the picture is too large and requires high hardware, so it should be set according to the specific situation. For the board with general accuracy, it is good to use 400DPI, and the mobile phone board can be set above 1000dpi.
Post time: Feb-04-2021