PCB vacuum etching technology

Shenzhen xinmaolong precision circuit Co,.LtdRelease Time:2022-01-15

With the escalation and rapid expansion of the global electronic product market, the miniaturized, high-precision, ultra-fine circuit printed circuit board technology of electronic products is entering a period of rapid development. In order to meet the ever-increasing demands of the market, especially in the field of ultra-fine circuit technology, traditional and backward etching technology is being replaced by advanced vacuum etching technology. Therefore, as a first-line PCB circuit board manufacturer, Xinmaolong will take you to understand the details of this technology

Multilayer PCB

We all know that the surface of the copper clad laminate is not required in all places. In order to appear the circuit pattern, the circuit board manufacturer will remove the unnecessary copper conductors by chemical solution etching, leaving the copper conductors, which are formed by the subtraction method. Circuit patterns, called etching, are currently the mainstream of printed circuit board processing.

The key to etching is the etching solution, the operating conditions of the circuit board manufacturer and the etching equipment. At present, the main market is the acid copper chloride etching solution of copper chloride and hydrochloric acid, and the alkaline copper chloride etching solution of copper chloride and ammonia water as the mainstream. In the PCB manufacturer, the control of process parameters such as temperature, pressure, time and solution concentration makes the etching process in the best state. The etching equipment needs to be continuously improved around production efficiency, etching speed and etching uniformity. At present, the mainstream is the horizontal conveying spray type.

The German company PILL e.K. has released a new process technology, which can improve the fluidity of the etching solution on the surface of the board by absorbing the used etching solution, thereby preventing the "pool effect" from occurring. This method is called vacuum etching.

This method is confirmed by the uniformity test of etching. The foil-clad laminates with 35μm copper foil are etched on both conventional and vacuum etching machines, respectively. The etching stops when the copper foil in the middle of the board is etched to a thickness of 18μm. Full board copper thickness distribution. The copper thickness distribution obtained by conventional etching of PCB batch manufacturers is usually alpine in the center, while the copper thickness distribution obtained by vacuum etching is uniform. Within a length of 600mm, the thickness difference between the center and edge copper in conventional etching is about ±4μm (18-10μm), while the difference in thickness between the center and edge copper in vacuum etching is only about ±1μm (19-17μm), the latter is only four of the former. one part.

Circuit board manufacturers use vacuum etching machines to make circuit patterns with line width/line spacing ≤ 30/30 μm easy to achieve. In order to get the desired effect, factors such as vacuum strength, spray pressure and copper foil thickness need to be grasped. The suction amount of the vacuum nozzle in the etching machine to the solution on the board surface should be equal to or slightly larger than the spray amount. If the suction amount is small, the old solution will be retained. The spray pressure will affect the etching speed and the degree of side corrosion, but the pressure will destroy the anti-etching film, especially on fine-pitch circuit patterns. For lines with line width/line spacing = 30/30μm, the thickness of the copper foil to be etched under conventional equipment is less than 12μm, and the thickness of copper foil can also be processed in vacuum etching with a thickness of 18μm. Reference data, line width/line spacing = 30/30μm, using 18μm copper foil, spray pressure 0.1Mpa (1.02kgf/cm2) suction volume 40Hz (about 120L/min), to obtain a uniform circuit pattern.

This is the effect of vacuum etching technology. We can see that compared with traditional etching, vacuum etching is easier to control and more helpful to the efficiency of production.

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