Three dimension (3D) printing method for multilayer flexible circuit board

[0015] In order to make the above-mentioned features and advantages of the present invention more obvious and understandable, the following specific embodiments are described in detail with reference to the accompanying drawings.

[0016] The present invention relates to a 3D printing method of a multilayer flexible circuit board, which is carried out as follows:

[0017] 1) Provide a substrate material, which is composed of polyimide powder, polyester powder and acrylic UV shadowless glue; the materials provided as the metal conductor are copper powder, cobalt-chromium alloy powder, gold powder and silver powder. ;

[0018] 2) Start printing from the bottom circuit board of the multilayer flexible circuit board, and print each layer obtained by cutting layer by layer in a specific direction according to the 3D CAD model. The printing direction of each layer is the x-axis direction first and then the y-axis direction , The printing starting point is the top left corner of the bottom layer, and the printing direction of the entire multilayer circuit board is the x-axis direction first, the y-axis direction and the z-axis direction.

[0019] In the process of preparing the substrate, the printer nozzle sprays 10-40um acrylic UV shadowless glue each time, and sprays the polyimide powder on the glue with a thickness of 30-80um, and performs ultraviolet radiation every two to three layers.

[0020] Using laser engineering net shaping technology to print metal parts, the laser can choose carbon dioxide laser (output 10600nm far infrared light), neodymium-yttrium aluminum garnet laser (output 1064 nm near infrared light), and the laser power is respectively carbon dioxide laser 500 -2000w, the neodymium-yttrium aluminum garnet laser is 600-1500w. The laser focus diameter is selected according to the accuracy range: 1~8um. The higher the accuracy, the smaller the diameter and the relatively slower speed. The scanning speed is 5~10um/s. The thicker the printing thickness, the faster the scanning speed can be selected. The thickness of each layer of metal powder is 20-40um.

[0021] Metal powder, polyimide, and polyester powder are also bonded with acrylic UV shadowless glue.

[0022] Specific implementation process: The invention prints a four-layer flexible circuit board, figure 1 The middle number is 1, 2, 3, and 4; 4 is the top-most board for soldering electronic components, and 1 is the lowest-level circuit board. The printing direction of the entire circuit board by the 3D printer starts from the bottom layer, according to x→y→z, The material of the substrate is made of polyimide (PI) or polyester and acrylic UV shadowless glue, and the material of metal holes and other conductors is made of copper powder, cobalt-chromium alloy powder, gold powder and silver powder. If the initial position is the substrate part, the substrate is printed first. The specific implementation process is that the 3D printer jet system is excited by the digital signal, and the acrylic UV shadowless glue in the nozzle working cavity forms a continuous jet stream and ejects a layer through the nozzle 10 -40um thick adhesive layer, and then spray a layer of 30-80um polyimide (PI) or polyester powder on the adhesive layer through another nozzle. The scanning speed is: 5-20um/s, the slower the speed, the better the accuracy high. After spraying two to three layers of powder, UV light is irradiated to solidify the powder and glue.

[0023] If metal holes and other conductors need to be printed in the same layer, laser engineered net shaping (LENS) technology is used to print metal parts. The laser engineering net shaping technology can instantly melt the powder and form a deposition layer through the laser emitted by the laser, and realize the synchronous movement of the laser emission head and the nozzle through the three-dimensional intelligent mobile platform of the platform, so that the copper powder can be melted and deposited directly and quickly formed. The lasers used in the laser system can be carbon dioxide lasers and neodymium-yttrium aluminum garnet lasers. The laser power is 500-2000w for carbon dioxide lasers and 600-1500w for neodymium-yttrium aluminum garnet lasers. The laser focus diameter is selected according to the accuracy range: 1~8um. The higher the accuracy, the smaller the diameter and the relatively slower speed. The scanning speed is 5~10um/s. The thicker the printing thickness, the faster the scanning speed can be selected. The thickness of each layer of metal powder is 5-40um. The metal powder and polyimide (PI) and polyester powder contact parts are also acrylic UV shadowless glue to make the metal part and the substrate tightly bonded, and UV light is irradiated every two to three layers.

[0024] The foregoing descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made in accordance with the scope of the patent application of the present invention shall fall within the scope of the present invention.