The requirements of DIP through-hole technology for components
The through-hole component wave soldering process requires the through-hole component package to withstand the high temperature and time of the reflow furnace. The following figure is a connector that can be used for through-hole reflow soldering. In addition, there are certain requirements for pin formation . Specific requirements are as follows.
1. The temperature and time that the component package can withstand:> 230 ℃ / 65s (tin-lead process);> 260 ℃ / 65s (lead-free process).
2. The lead length of the component should be equal to the board thickness. After insertion, it has a square or U-shaped cross section (rectangular is better).
3. If there are aluminum electrolytic capacitors and domestic plastic packaging devices, it should be solved by manual welding. This is also the most common solution in PCB SMT processing.
DIP through-hole component requirements for solder paste volume
Due to changes in factors such as different solder alloy components, pin conditions, reflow characteristics, etc., it is difficult to accurately calculate the shape and volume of the solder wetting angle, so a simple approximation method can be used to determine the volume of solid solder joints.
Ideal solid metal solder joint volume = welding surface and component surface wetting angle solid metal volume + solid metal volume in the insertion hole solid metal volume in the insertion hole = total volume of the through hole after electrical recovery-the volume of the component pin.
When the solid metal volume of the solder joint is calculated, the volume of solder paste required is calculated as a function of alloy type, flow density, and mass percentage of metal in the solder paste.
Since the solder alloy in printing solder paste only accounts for about 50% of the volume, the other 50% of the volume is flux, solvent and other additives, which will volatilize and disappear in the air at the soldering temperature. Therefore, the ideal solder paste volume ≈ solid metal volume × 2.
If the solder paste dispensing process is used, the volume ratio of the solder alloy to the flux is lower, and the volume of the solder paste needs to be increased, which is approximately: the ideal volume of the solid solder volume x 2.5. Therefore, when using the spot solder paste process, it is also necessary to grasp the appropriate amount of solder paste.
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