Introduction
Nowadays, circuit boards use more SMD components than plug-in components, but for those electronic products with higher heat dissipation requirements, the performance of plug-in components will be better than that of SMD components. In addition, the external interface of the motherboard and the devices of the connector all use plug-in pins, such as USB, HDMI, network ports, and other devices.
Regarding the square pins of plug-in devices, there are manufacturability issues in DFM analysis. Device pins are generally round or oval, but the pins of some pin header devices are square. Square pins are not very convenient when making packages, even if some EDA software can make packages with square pins. However, square pin holes cannot be made on the manufacturing side because the drilling tip is round.
Square Pin Drawing Method
1. Allegro draws square pins
First, open the Padstack Editor package drawing tool. During the package drawing process, just change the Hole type of Drill to Square. The shape of the plug-in pin is considered square.
2. PADS draws square pins
PADS software does not have the function of drawing square pins. If the plug-in device pins are square and need special processing, you can use 2D lines in the Drill Drawing layer to draw rectangles according to the pin size, and use text to specifically indicate that a square pin hole is required here.
Square Pin Processing Method
1. CAM software recognition of square holes
For square holes, the existing CAM software cannot recognize them and can only recognize circular or elliptical holes and slots. Wonderfulpcb DFM service can recognize square drill holes and slot holes and can analyze design files with square holes, prompting that the design files have square holes to avoid missing square drill holes during production.
2. Processing method for square holes and square slots in production
Currently, the drilling machine in the industry cannot drill square holes, because the drill bit of the drilling machine drills the holes required by the PCB board through high-speed rotation, so the holes drilled are circular or elliptical.
So how to solve the problem of square holes? The drilling machine can only meet the square hole requirements by drilling more holes. For example, first drill a circular hole according to the diameter of the pin, and drill 4 small holes at the square corners to meet the square pin plug-in requirements.
3. Limitations of square hole processing
Although it is written above that there is a method for processing square holes, the drilled holes are circular after all. Even if small holes are used to drill square corners, 100% right angles cannot be achieved. If there is a slight deviation, the device may not be inserted.
Therefore, it is recommended that design engineers draw the size of the pins slightly larger when drawing the package pins to avoid the problem of the device not being able to be inserted after production.
