Line design
The most commonly used specifications of low-voltage led light strip are 12V and 24V, and 12V is a three series and multi-channel parallel structure.
24V is a six series and multi-channel parallel structure. As LED light strips are to be connected for use, the specific length of each light strip is closely related to the width of the line and the thickness of the copper foil when designing. Because the current strength that can be withstood per unit area is related to the cross-sectional area of the circuit. If this is not taken into account when wiring, when the connection length exceeds the current that can be withstood by the circuit, the light strip will heat up due to overcurrent, which will reduce the service life of the led while damaging the circuit board.
Production process
As the LED light strip is in series parallel structure, when there is a short circuit in a group of circuits, it will lead to the increase of other LED voltages in the same group, the brightness of LED will increase, and the corresponding heating capacity will also increase. The most obvious thing is that in the 5050 light strip, when any chip circuit of the 5050 light strip is short circuited, the current of the lamp bead that will cause the short circuit will double, that is, 20mA will become 40mA, the brightness of the lamp bead will become very bright, but at the same time, the heat output will also increase dramatically, and in serious cases, the circuit board will be burned in a few minutes. However, because this problem is obscure, it is generally not paid attention to, because short circuit does not affect the normal lighting of the light strip. If the staff in charge of testing only pay attention to whether the LED lights up, instead of checking the abnormal brightness, or do not do visual inspection, but only do electrical testing, this problem is often ignored, This is why many LED light strip manufacturers often encounter customer complaints that the product is hot but can not find the reason.
terms of settlement:
1. Circuit design: the circuit shall be wide enough for wiring as far as possible, and the spacing between lines shall be 0.5mm. The rest of the space shall be fully arranged. The thickness of the copper foil shall be thickened as much as possible without violating the customer's requirements for the total thickness of the circuit board. Generally, the thickness is 1~1.5 OZ
2. Production process:
A/When printing solder paste, try not to make soldering pads connected to each other to avoid welding short circuit caused by poor printing;
B. Avoid short circuit when mounting
C. Check the tip position before reflow
D. After reflow, conduct appearance inspection first to ensure that there is no short circuit in the light strip, and then conduct electrical measurement recheck. During recheck, pay attention to whether the LED is abnormally bright or dark when it is lit.
LED light strip shopping guide
The purchase guide of LED light strip is as follows:
1. Chips used for LED light strip: Chips include domestic and Taiwan chips, as well as imported chips (including American chips, Japanese chips, German chips, etc.). Different chips have different prices. The most expensive chip in the market is American chip, followed by Japanese chip and German chip, and the moderate price is Taiwan chip. What chip is used? What effect do you want to achieve? Be sure before purchasing.
2. LED packaging: resin packaging and silicone packaging. The price of resin packaging should be cheaper, because the heat dissipation performance is slightly poor, and everything else is the same. The heat dissipation performance of silicone encapsulation is good, so the price is a little more expensive than that of resin encapsulation.
3. Consistency of LED color: There are many packaging plants in China, including thousands of large and small ones. Of course, there are strengths and weaknesses. There are many small packaging plants that do not have light and color separators, so they either do not have light and color separators or send out, which is difficult to guarantee the quality. The LED without light and color separation has poor color consistency. The effect is not so good when it is installed on the LED light strip. Of course, the price difference is also large.
4. LED welding effect: The assembly of LED light strips can be divided into two types: worker welding and machine welding. Manual welding is to use a soldering iron, using the most original method for welding. The amount of solder at the solder joints is uneven, and most of the solder legs are wrapped in a circle. At the same time, tin tips of different degrees appear. This is a typical phenomenon of manual welding. The products produced by this operation mode are ugly (inconsistent solder joint size, excessive flux residue, unsmooth solder joint, and burnt LED package, etc.), and poor electrostatic protection measures. Many LED chips are broken down, resulting in the phenomenon of slightly bright or not bright when powered on. Machine welding is different. It is produced by SMT chip process, solder paste and reflow soldering process. Therefore, the solder joints on the LED light strip are smooth and the amount of solder is not large. The solder joints extend from the FPC pad to the LED electrode in an arc shape. Not only do the products look beautiful after welding (the solder joints are uniform in size, smooth, no flux residue, and the LED package is intact), but also the chips will not be damaged by static electricity. At the same time, the position and direction of LED are beautiful. This can be seen directly from the appearance.
5. FPC material: FPC is divided into calendered copper and coated copper. The coated copper plate is cheaper and the calendered copper is more expensive. The bonding pad of the copper clad plate is easy to fall off when it is bent, while the calendered copper will not. The specific material FPC to be used depends on the purchaser's decision according to the use environment.
6. Has FPC passed the environmental protection certification and UL certification? Whether the LED has patent, etc. There are certified and patented ones, which are expensive, but none are cheap.
7. LED brightness: The price of LED with different brightness is different, and the price of ordinary brightness and bright LED is quite different. Therefore, when purchasing, you must clearly know what kind of brightness you need, so that you can accurately position your products.
8. LED color: different colors, different prices. The price of white and green is higher than that of other colors because color matching and light separation are difficult; Red, yellow, blue and other colors are easy to separate light and color, and the consistency is good, so the price is a little cheaper. Special colors such as purple and brown are the most expensive due to color matching.
9. LED size: LED of different specifications and sizes have different prices. For example, the prices of LED 0603 and LED 1210 (i.e., LED 3528) differ greatly; The price of 1210 and 5050 LED is a step different.
10. Check the cleanliness of the surface of the LED light strip. If the LED light strip produced by SMT process is used, its surface cleanliness is very good, and no impurities and stains can be seen. However, if the fake LED light strip produced by hand welding process is used, no matter how it is cleaned, there will be stains and cleaning traces on its surface. At the same time, there will be flux and tin slag residues on the surface of FPC.
11. Look at the package. Regular LED light strips will be packed in anti-static reels, usually 5m or 10m, and then sealed with anti-static and moisture-proof packaging bags. For the sake of saving costs, the counterfeit LED light strip will use the recycled coil tray, and then there is no anti-static and moisture-proof packaging bag. A careful look at the coil tray can show that there are traces and scratches left when the label is removed.
12. Look at the label. The regular LED light strip packaging bag and reel will have printed labels instead of printed labels. The counterfeit labels are printed, and the specifications and parameters are not uniform.
13. See the attachment. Regular LED light strips will be attached with instructions and specifications in the packaging box, and LED light strip connectors or card holders will also be equipped; However, the counterfeit LED light with these accessories is not in the packaging box, because some manufacturers can save money after all.
How to choose LED light strip in home decoration What are the precautions for installing LED light strip
What are the precautions for the installation of LED light strip
Precautions for the installation of LED light strip: The connection method of LED light strip The general voltage of LED light strip is 12V DC, so it needs to use switching power supply. The power supply size depends on the power and connection length of LED light strip. The wiring of the monochrome 5050 chip LED light strip is to distinguish the positive and negative poles. Generally, we provide a welded power plug, which can be directly plugged into the power supply of the light strip provided by us. Then, all the input power supplies of the LED light strip are connected in parallel, and the power supply is uniformly supplied by the main switch power supply. Precautions for the installation of LED light strip: the connection mode of the controller: LED horseback lamp strip and RGB slide lamp strip need to use the controller to achieve the variable effect. When wiring.
