Why are there holes in the circuit board? What is PTH/NPTH/ VIAS

Posted on 2022-04-22

如果您有机会触摸印刷电路板 (PCB),您会发现很多大大小小的孔。把它捡起来看看天花灯,也有很多紧密的孔。这些孔很轻,不是为了美观而配置的。每个孔都是为了一个目的而设计的,孔越多,PCB就越贵。

PCB 上的这些孔分为两大类。PTH(信息厅,信息厅)和NPTH(非信息厅,非信息厅)。这实际上是从董事会的一侧到另一侧。事实上,除了板子上的通孔外,还有其他不穿过板子的通孔。有兴趣的朋友可以参考这篇文章:PCB术语说明:通孔、停止孔、埋孔。





此外,一些 PCBS 在电路板边缘(断路器、试样、断路器)设计有 NPTH,用于定位测试组件,最初用于固定电路板。附有 SMT 零件/安装。为此,几乎所有的SMT机器都开始使用卡尺将电路板固定到位。然而,太薄的电路板可能需要用 NPTH 固定,以避免卡尺变形。



一般来说,电路板上的 PTH 孔有两个用途。一种用于焊接传统 DIP 部件。这些孔的直径必须大于零件焊脚的直径,这样零件才能插入孔中。焊接。

Another, smaller PTH, commonly called conventional through-holes, is used to connect and conduct copper foil wires between different layers of a circuit board (PCB). Yes, PCB is basically made up of many overlapping copper foil layers with adjacent copper foil (copper) layers equipped with an insulating layer so that the copper foil layers cannot communicate with each other. Because signal transmission between different copper foil layers depends on BIA, it is called “beer house” in Chinese. You can imagine the various layers of copper foil on the various floors of a large shopping mall, and the beer house is like a staircase with multiple steps.

The photo on the left of Blind- via-hole is a cross section of the circuit board. Think of it as an ant’s nest in a glass jar. This is a PCB with six layers of copper foil. This PCB can be imagined as a six-story building. In the building, the layers of copper foil represent the floor, and the bia (BIA) corresponds to the staircase connecting the floor. The building has multiple stairs, but not all of them. Connect to all floors. Only the 3rd and 4th floors can be connected, the rest of them can’t. Such a bia is called a “filled beer house” because the hole is completely invisible from the outside. The purpose of bia is to conduct different layers of copper foil, conduction needs electroplating, so Bia is also a PTH.

Green paint covers vias, now most vias are covered with green paint (snow mask) as shown on the left, due to the parts on the boards, the surface is insulated, especially the mobile phone boards. More and more configured. High density, there are also things with harpoons right under the parts. Most billets are covered with green paint to prevent quality or functional problems from parts or billets short-circuiting by mistake.

Another purpose was to print the semisub on some beya sauce. Most PCB processes now create openings because the board flows in the reflux oven (reflux) and solder paste can flow from the groove to the other side of the board, causing short circuit problems. Of course, in order to avoid possible future quality problems, cover it with a small piece of green paint, as Gerber requested.