How to control PCB coping accuracy

The accuracy of PCB copying depends on two steps, one is the accuracy of software, the other is the accuracy of original image. At present, all kinds of board copying companies, in the board coping accuracy of technical ability is not uniform, some companies have poor board coping technical ability, board coping accuracy is not high, and some board coping technical ability is strong, board coping accuracy can reach 1mil or less. Then how to control PCB coping accuracy?

How to control PCB coping accuracy

For software precision using 32-bit precision floating-point representation can say there is no limit, so the main still depend on the original scanning image accuracy, for example, if with pictures of 1 million pixels making can wash 5 inch photos, but if you want to wash it into 20 inches of photographs that simply can't see clearly, is the same reason, so for a high precision circuit board, to take out very high precision PCB diagram, be about to choose when scanning high DPI.

DPI is how many dots per inch. In other words, the distance between each of the two points in the scanned image is 1000/DPI, mil. If DPI is 400, then the distance between two points on the image is 1000/400=2.5mil, which means the accuracy is 2.5mil. This is the most scientific basis, so some people say that the accuracy can be less than 1mil, that has a premise. In fact, the accuracy of copying mainly depends on the original scanning accuracy.

To sum up, the setting of DPI when scanning the board should be based on the accuracy required by the actual board. If the accuracy is required below 1mil, such as the line spacing of mobile phone board, then the scanning DPI should be set above 1000DPI. Current scanner 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 the hardware requirements are high, so it should be set according to the specific situation. For the general accuracy of the board is generally used 400DPI is good, mobile phone board and so on can be set at more than 1000DPI.