What is the difference between the exposure of LED aluminum substrate and the screen printing process?

In addition to the exposure of the LED aluminum substrate, there is also a screen printing process. The price of the exposure process is higher than that of the screen printing. Is the utility obtained just to make the circuit look better? The circuit of the screen printing process can still operate, and the lamp beads can still be lit. The exposure process is higher than the price, but the utility is relatively small. Whether it is exposed does not affect the brightness, nor does it affect the life of the lamp beads, and it will not increase the heat dissipation and withstand voltage. So what is the difference between the exposure of LED aluminum substrate and the screen printing process?

1. The exposure process is to transfer the image on the original negative film to the photosensitive base plate by the action of a light source.

The ink used for exposure is photosensitive ink, which is produced in a dust-free workshop. Because it is necessary to ensure that the ink on the board surface is free of any garbage and granular, the thickness of the ink must reach 15UM to 20UM, which can ensure that the ink on the board surface does not turn yellow after 280 degrees, and the light return rate reaches more than 90%. This creates a photosensitive process production cost and efficiency problems, so the PCB price is high. Like some 4MM board width and 0.2 line width and line spacing, high-precision board screen printing processes cannot meet this requirement.

2. The screen printing process is to print the shape, serial number and other explanatory text of the components on the component surface or solder surface through screen printing to facilitate the plug-in of the circuit board production process (including the placement of surface-encapsulated components) and future product maintenance operations.

Light-solid/thermosetting ink is used for screen printing. You can produce screen printing in one room at will, but the smoothness of the board itself and the thickness of the ink cannot be guaranteed. If it is white for a long time, it will be prone to yellowing and other phenomena, and the required light return rate cannot be reached.

However, some precision levels are not up to the requirements, such as a 3014 lamp bead pad, and if the screen printing process is used to make it, the pad will be much smaller, and the edge of the pad will be jagged and uneven, which will easily cause the difficulty of brushing solder paste and sticking lamp beads.