Packaging method of LED (light-emitting diode) flexible lamp strip

[0019] Reference figure 1 , A method for packaging LED flexible light bars of the present invention includes the following steps:

[0020] 1) Provide a flexible circuit board 1;

[0021] 2) Provide several in-line or SMD LED light sources 2;

[0022] 3) Soldering the above-mentioned LED light source 2 on the above-mentioned flexible circuit board 1 by reflow soldering or wave soldering;

[0023] 4) Provide a long strip of flexible shell 3;

[0024] 5) Lead the above-mentioned flexible circuit board 1 with the LED light source welded into the above-mentioned flexible housing 3;

[0025] 6) Pour glue into the flexible shell 3 and let it dry and solidify.

[0026] The above technical solution may also have the following improvement solutions: the step 5) includes the following steps:

[0027] ① Pass the steel wire through the flexible shell, and both ends of the steel wire are exposed outside the flexible shell;

[0028] ②Connect the end of the flexible circuit board to the steel wire and fix the end of the flexible circuit board in one end of the flexible housing;

[0029] ③ Pull the steel wire evenly at the other end of the flexible shell to cause all the flexible circuit boards to enter the flexible shell;

[0030] ④Remove the steel wire and check the flexible circuit board.

[0031] The invention also needs to solder related resistors, ICs and other electronic components on the flexible circuit board.

[0032] The flexible circuit board of the present invention can be an FPC circuit board, and the flexible casing can be a PVC flexible casing. When the circuit board is threaded, the FPC circuit board and the PVC casing must be dry and clean. The surface of the components used must be smooth, and the shell should not be scratched or contaminated during operation; when threading the circuit board, carefully check whether the electronic components have virtual soldering, whether the circuit board is short-circuited, whether the directions of the components are consistent, and whether the soldering tin Uniformity, whether the size of the solder joints is the same, whether the solder joints of the connection joints are sideways or too large, whether the connection between the circuit boards is firm, confirm the front and back of the PVC shell, etc., pay attention to the indoor temperature, humidity and dehumidification during this operation Control the cabinet temperature and do a good job of preventing dust and static electricity.

[0033] The presence of solder balls during reflow soldering and wave soldering indicates that the process is not completely correct, and there is a danger of short circuits in electronic products, so it needs to be eliminated. The internationally recognized standard for solder balls is: printed circuit components cannot have more than 5 solder balls within 600. There are many reasons for solder balls, and the root of the problem needs to be found. Tin balls in wave soldering There are two main reasons for solder balls in wave soldering. First, when the printed board is soldered, the moisture near the through hole on the printed board is heated and turns into steam. If the metal plating of the hole wall is thin or there is a gap, the water vapor will be removed through the hole wall. If there is solder in the hole, when the solder solidifies, the water vapor will create a gap (pinhole) in the solder, or extrude the solder on the front side of the printed board. Produce solder balls. Second, the solder balls produced on the reverse side of the printed board (that is, the side contacting the wave crest) are caused by improper setting of some process parameters in wave soldering. If the amount of flux coating is increased or the preheating temperature is set too low, it may affect the evaporation of the components in the flux. When the printed board enters the wave crest, the excess flux will be evaporated at high temperature and the solder will splash out from the tin bath. Irregular solder balls are produced on the printed board surface. In view of the above two reasons, we take the following corresponding solutions: First, the appropriate thickness of the metal plating in the through hole is very important, and the copper plating on the hole wall should be at least 25um, and there should be no voids. Second, use spray or foam to apply flux. In the foaming method, when adjusting the air content of the flux, the smallest possible bubbles should be generated, and the contact surface between the foam and the PCB should be relatively reduced. Third, the temperature of the preheating zone of the wave soldering machine should be set so that the temperature of the top surface of the circuit board reaches at least 100°C. Proper preheating temperature can not only eliminate solder balls, but also prevent the circuit board from being deformed by thermal shock. During the component mounting process, the solder paste is placed between the pin and the pad of the chip component. As the printed board passes through the reflow oven, the solder paste melts and becomes liquid. If the wetting is not good, the liquid solder will shrink and cause insufficient filling of the solder joint, and all solder particles cannot aggregate into a solder joint. Part of the liquid solder will flow out of the solder joints and form solder balls. Therefore, poor wettability of solder with pads and device pins is the root cause of solder ball formation.

[0034] The specific operation of injecting glue to dry and solidify is as follows:

[0035] ①Glue preheating; ②Glue preparation; ③Glue injection; ④Curing; ⑤Clean the surface.

[0036] When the glue is preheated, the preheating temperature of the oven is controlled at about 40-60 degrees, and the time is controlled at 5-10 minutes; when the glue is prepared, the room temperature is controlled at 20~25℃, and the humidity is controlled at 45%~70%RH. , Strictly follow the parameter ratio of the glue and stir uniformly. The time control depends on the amount of glue. Generally, the greater the proportion, the more intense the reaction between the main agent and the curing agent, and the faster the curing speed, so the glue used The shorter the time. Generally, the time for 100 grams is controlled at about 40 minutes (from the beginning of the dispensing to the end of the potting); the room temperature of the potting room is controlled at 25±5°C, and the humidity is controlled at 60% to 80% RH to maintain environmental hygiene. The glue in the glue filling machine is strict, pay attention to safety during operation, and wear gloves when operating to prevent hands from being crushed by the pushing table. It is necessary to wear gloves when filling the glue to avoid the glue splashing on the skin. The speed of the glue should not be too fast to avoid bubbles. Therefore, vacuum must be drawn before the glue and the time is controlled within 3-5 minutes. Glue curing generally takes 36-58 hours at room temperature; for example, the heating and curing temperature is controlled at about 50 degrees for 3.5-5 hours; the light bar must be square during curing, and the surface of the light bar cannot be covered by hand. To prevent deformation of the light bar. During this period, it is not possible to increase the curing speed by energizing to prevent small bubbles around the components when the vacuum is not complete. As the temperature of the device rises, the bubbles become larger, which seriously affects its appearance; clean up after curing The residual glue on the surface of the shell can be rubbed gently with your hands. Do not scratch the surface with a knife to avoid scratches; try not to wipe the surface with acetone, because; ①The smell is strong. ②After the acetone is wiped, it should be washed with water to change it, so that there is one more process. ③Avoid turbidity on the shell surface. If you need to use acetone, it must be washed with water. Remember not to wipe the surface with a depilatory cloth. It is best to leave it to dry naturally. After curing, put the light bar in water and use a 12V DC power supply to charge it for 12-24 hours, if the time is tight, 6 hours.

[0037] If you produce LED flexible strips and flexible light strips, they can be composed of in-line LEDs and patch LEDs, and use low-voltage DC power supply, which is safe and convenient. Waterproof grade IP67, can be completely placed in the water, 3528 and 5050 are available in various colors including full color.

[0038] The product advantages of the present invention: 1. Shell color: milky white, transparent; 2. Shell material: PVC, PC plastic, waterproof, dustproof, UV resistant, pressure resistance, crack resistance, high and low temperature resistance, flame resistance, super impact resistance and aging . The product of the present invention can be widely used in: 1. Building decoration lighting; 2. Corridor lighting; 3. Stair lighting; 4. Concealed position lighting; 5. Backlight source of advertising characters.

[0039] In addition, the present invention is not limited to the above-mentioned embodiments, as long as it achieves the technical effects of the present invention by basically the same means, it should fall within the protection scope of the present invention.