| CPC H05K 3/305 (2013.01) [B60R 11/0235 (2013.01); H05K 3/365 (2013.01); H05K 2201/10098 (2013.01); H05K 2201/10106 (2013.01); H05K 2203/085 (2013.01); H05K 2203/104 (2013.01); H05K 2203/107 (2013.01)] | 5 Claims |
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1. A production process of a flexible light-emitting diode (LED) vehicle-mounted display screen, comprising the following steps:
S1. adopting a flexible printed circuit (FPC) as a basic material of a display screen main body, and mounting an LED lamp bead, a microcontroller unit (MCU) and a drive integrated circuit (IC) on the FPC to form a flexible screen;
S2. fixing the flexible screen in a vacuum box through a mold;
S21. if a bracket of the LED lamp bead is made of a magnetic material, embedding a magnet strip into a mold tray, and fixing the flexible screen on the mold tray by attraction of a magnet to the magnetic material;
S22. if a bracket of the LED lamp bead is made of a non-magnetic material, adopting a hollow mold tray, covering a layer of silica gel sheet right above the mold tray, arranging a plurality of through holes on the silica gel sheet at equal intervals, and sealing the silica gel sheet and a mold edge by using glue; after the flexible screen is placed on the mold tray, extracting air inside the mold tray, and adsorbing the flexible screen on the mold tray by negative pressure;
S3. polyurethane (PU) glue mixing: accurately weighing a component A and a component B, and uniformly mixing to obtain the PU glue;
S4. degassing treatment: placing the mixed PU glue in a vacuum for degassing treatment to remove bubbles generated during the mixing process;
S5. first-time glue dripping: dripping the degassed PU glue on the lamp bead of the flexible screen in the vacuum box, covering a bottom of the lamp bead and waiting for solidification;
S6. detecting an air pressure of the vacuum box in real time by adopting an air pressure sensor, photographing and analyzing expansion of bubbles with a camera, feeding the air pressure back to an electronic system MCU, and keeping the vacuum degree in the vacuum box stable by controlling a solenoid valve so as to ensure that the bubbles stably expand at a preset height;
S7. filling a surface by performing second-time glue dripping, and leaving the PU glue naturally cured or cured by a ultraviolet (UV) light;
S8. collecting: for the step S21, directly taking off the cured flexible screen; and
for the step S22, after the glue is dripped, opening an exhaust hole so as to release the vacuum and remove the flexible screen by an operator;
wherein in the step S3, the component A is polyester polyol or polyether polyol, the component B is isocyanate, and the components A and B are mixed in a ratio of 1:1 to prepare the PU glue;
the FPC comprises a bottom coating, a bottom copper foil circuit, an intermediate substrate layer, a top copper foil circuit, and a top coating stacked in sequence, the bottom coating and the top coating have openings to expose the copper foil circuit, which is connected to a device pad through tin to achieve an electrical connection;
for the step S6, a solenoid valve and a vacuum pump are opened by an electronic system to pump an air pressure in the vacuum box to a set val of −25 kpa, when the camera captures bursting of large bubbles, the electronic system reduces the air pressure to −50 kpa and maintains the air pressure for 3-8 seconds, if the camera captures the bubbles expanding more than the preset height, the electronic system controls an air valve to let in air to increase the air pressure and prevent glue overflow, and finally, the solenoid valve is fully opened to allow the vacuum pump to pump out remaining air and remove tiny bubbles.
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