LED lamps as a new type of green lighting, energy saving, environmental protection, long life, by the majority of customers chasing. But the problem of LED light failure, but also a LED lighting had to face the problem. Uninterrupted light failure, seriously affected the use of LED lamps.
For now, the phenomenon of white LED light on the market may be one of the primary problems into the civil lighting. What causes the LED light failure it? In general, for the LED light failure there are two main factors:
First, the LED product itself Quality:
1, the use of LED chip is not good, brightness attenuation faster.
2, the production process defects, LED chip cooling can not be a good export from the PIN pin, resulting in LED chip temperature is too high chip attenuation intensified.
Second, the use of conditions:
1, LED constant current drive, some LED voltage driven by the use of LED attenuation.
2, the drive current is greater than the rated drive conditions.
In fact, many causes of LED light failure, the most critical or hot problem, although many manufacturers in the secondary products do not pay special attention to the issue of heat, but these long-term use of LED products, the degree of light will be more than the degree of heat Of the LED products to high. LED chip itself, the thermal resistance, the impact of silver, the substrate cooling effect, as well as colloid and gold lines are also associated with the decline of light.
Three factors that affect the quality of LED lamps
First, choose what kind of LED white light.
This is very important, the quality of LED white light can be said to be very important factor. Give some examples, the same crystal to the 14mil white chip as the representative of the ordinary epoxy resin to do with the end of plastic and white plastic and plastic encapsulated out of the LED white light, single light in the 30-degree environment, After a thousand hours, the attenuation data for the luminous retention rate of 70%; if the use of D-type low-drop glue package, in the same aging environment, thousands of hours of light failure of 45%; if Class C low-loss glue package, in the same aging Environment, the 1000 hours of light failure of 12%; if the B class low-loss glue package, in the same aging environment, thousands of hours of light failure of 3%; if A low-loss glue, in the same aging environment, thousands of hours Light failure of 6%.
Second, LED lamp beads working environment temperature.
According to the data of a single LED white light aging, LED white light if only one light work, at the same time, it is in the ambient temperature is 30 degrees, then, single LED white light work when the stent temperature will not More than 45 degrees. This time, the LED life will be very good.
If there are 100 LED white light at the same time lit work, the interval between them is only 11.4mm case, then the lamp stack around the LED white light stent temperature may not exceed 45 degrees, but the middle of the lamp stack Those LED white light is likely to reach 65 degrees high temperature. This time, the LED lamp beads is a test. So, gathered in the middle of those LED white light, the theory of light failure will be faster, and the lamp around the LED white light, light failure will be slower.
Anyway, we should know, LED is afraid of heat, the higher the temperature, LED life is shorter, the lower the temperature, LED life longer. The ideal operating temperature of the LED is of course between minus 5 and zero. But this is basically impossible.
So, we understand the LED lamp beads ideal working parameters, as far as possible in the design of lighting, strengthen the thermal, cooling function. Anyway, the lower the temperature, the longer the LED life.
Again, LED lamp beads work electrical parameters design.
According to the experimental results, LED white light in the drive current lower case, the smaller the heat of launch, of course, the brightness is also smaller. According to the survey, LED solar lighting circuit design, LED drive current is generally only 5-10mA; lamps used in the lamp beads with a large number of products, such as more than 500, or more, the drive current is generally only 10-15mA , While the general popularity of the LED application lighting drive current, only 15-18mA, few people to the current design to 20mA or more.
The experimental results also show that in the 14mA drive current, and, plus the lid is airtight, the air temperature inside the 71 degrees to the environment, low-melting products, thousands of hours of light failure is zero, 2000 hours light failure of 3% , Which shows that this low-decline LED white light in such an environment has reached its maximum, and then is a big damage to it.
Because the aging of the aging board with no cooling function, so the heat generated when the LED is basically can not be transmitted to the outside. Experimentally proved this point. Aging plate inside the air temperature has reached a high temperature of 101 degrees, the aging board on the surface temperature of the lid is only 53 degrees, a difference of tens of degrees. This shows that the design of this plastic cover is basically no thermal conductivity. But the general design of the lamp, are taking into account the thermal function of heat. Therefore, the summary, LED lamp beads of the electrical parameters of the design according to the actual situation, if the lamp heat conduction function is very good, LED white light drive current increase is that it does not matter, because the LED lamp beads work Heat can be exported to the outside instantly, no damage to the LED, is the best care of the LED. On the contrary, if the lamp heat conduction function so-so, it is best to design a little smaller circuit, let it put some less heat out.