I have visited many PCB processing plants, and many PCBA processing workshops have a prefabricated material molding room. Prefabricated material, so what is prefabricated material? Today fastpcba electronics will analyze some information about the prefabricated solder prefabrication method in the chip processing.
Solder preforms are stamped out of 100% solder alloy, and are taped and packaged like chip components. As shown in the figure, the placement machine can be used for high-speed pick-and-place. Pre-formed solder tabs are another way to provide the required solder volume.
The application and advantages of solder preforms: When the THC such as PGA matrix connector has a lot of terminals (pins), increasing the thickness of the template will affect the printing quality; increasing the opening size will cause the solder paste to stick, resulting in a large number of solder balls. Adopt first printing or drop
After applying solder paste, add solder preforms next to the solder paste pattern (end). Since the preform is a 100% solder alloy, the amount of flux will not increase. Therefore, the amount of alloy is increased while avoiding solder paste adhesion. There are several placement methods for solder preforms.
1. Process the proper nozzle and mount it on the pad of the through-hole component with a placement machine. This method first prints solder paste on the through-hole pads,
Then, just like mounting chip components, pick/place rectangular solder preforms with a placement machine.
2. Put the washer-shaped solder top piece on the pin in advance through the mold. This method requires processing a matrix mold matching the connector pins (pins) according to the outer diameter, inner diameter and thickness of the gasket-shaped solder preform.
The process of placing solder preforms: first sprinkle the preforms on the mold and vibrate, screen them into each hole of the mold, and remove the excess pieces: then press the pins of the connector into the mold holes : Finally pull out the connector. When the connector is pulled out, because the solder tabs are relatively soft, the pieces in the mold are put on each pin separately. As shown in the figure; then. Then insert components and reflow soldering.