A complete PCB board was made from a variety of electronic components, such as resistors and capacitors according to the schematic design of the layout of the connections. These electronic components to be firmly installed on the PCB board, it need to use SMT processing technology to complete.
So, what matters of SMT chip processing should be noted?
1. First of all, we need to well know the safe operation precautions of placement machine.
2. Generally, the temperature specified by the SMT processing plant is between 25 ± 3 ° C.
3. When solder paste printing, need to prepare tools paste, steel, scraper, wipe paper, clean paper, detergent, agitating knife, etc.
4. Commonly used solder alloy composition of Sn / Pb alloy, and the alloy ratio of 63/37.
5. The main component of paste is divided into two parts with tin powder and flux. The main role of flux in welding is to remove oxides, destroy the surface tension of molten tin, and prevent further oxidation.
6. Tin powder particles with the solder paste Flux in a volume ratio of approximately 1: 1， the weight ratio is about 9: 1. In the use of paste, it need through two processes of temperature back and stirring.
7. The technical approval standard for tin balls is when the distance between the pad or printed wire is 0.13 mm. The diameter of paste ball should be less than 0.13mm. In the range of 600mm square can not appear more than five tin beads.
8. Storage required after completion of SMT patch, in the storage process should pay attention to packaging, and placed in a dry environment, to avoid moisture.
The above is SMT chip processing considerations.