The first case is that a via is required on the pad, for example:
In order to improve the heat dissipation of the MOSFET, we make a via on the MOSFET pad.
Note: When handling the vias of large pads here, we need to evenly distribute the holes to ensure that the pads are evenly heated.
Generally, the resistors and capacitors of the label are used to prevent the tombstone, and we need to do window processing.
The phenomenon of "stray" often occurs in the reflow soldering process of CHIP components (such as chip capacitors and chip resistors), and the smaller the component volume, the easier it is to occur. Especially in the production of 1005 or less fishing 0603 patch components, it is difficult to eliminate the phenomenon of "steep monument". In the reflow soldering process of the surface mount process, the chip component will have the defect of being lifted off due to the erection, as shown in Fig. 4, which is aptly called the "steep monument" phenomenon (some people call it "Manhattan" phenomenon). .
The "tombstoning" phenomenon occurs because the surface tension of the two soldered ends of the components is unbalanced when the solder paste on the pads at both ends of the device is reflowed, and the one end with the larger tension pulls the component to rotate along the bottom thereof. There are also many factors that cause tension imbalance.
Therefore, in general, we will do the copper-plated pins, open the window to prevent the phenomenon of tombstoning; similarly, we can not put the vias on the SMT pads to prevent the surface tension of the two Han ends of the components from being unbalanced.
DC Capacitor For Electric Furnace
DC Capacitor For Electric Furnace
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