As a relatively mature application of LED lighting, LED bulb lamp has entered the stage of large-scale production. The LED bulb is made up of lamp beads and baseplate, radiator shell, bubble shell, driver, lamp holder and so on. In the process of assembling the LED bulb, the organic silicone material can be used as shown in the following figure:
Aluminum shell and bubble shell are usually bonded with a single component RTV adhesive; Qianjing technology model QK-8501 series; lamp beads and aluminum substrate heat conduction, PCB and aluminum substrate heat conduction is generally used thermal silicone grease and thermal conductive silicone; Qianjing technology models are QK-850-1 series QK-302 QK-851W-2, etc. The general use of lamp body filling is to add Forming heat conduction filling adhesive, Qianjing Technology for the model is QK-850-AB, with the expansion of production scale, product quality is particularly important, the following LED production often appear in the fog phenomenon to do a brief analysis, I hope to be useful to everyone.
If the "water mist" is water, it is likely that the fitting environment temperature is too high, when the assembly of humidity stuffy inside the hood, LED lighting temperature difference between the inside and outside, humidity encounter the hood condensation form water mist attached to the mask (this is the same as the winter window mist), to solve this problem, it is necessary to equip the car. Dehumidifying and controlling the humidity of workshops can dehumidification and assembly of workpieces. In the absence of dehumidification equipment, the easiest way to do this is to dry the hood with a hot air gun and then assemble the LED lamp holder. Also, if the use environment of lamps and lanterns is heavy, consider the waterproof structure.
If the "water mist" is any other chemical, it is the volatile heat conductive silicone ester or sealant, which evaporates heat and forms a mist attached to the mask. The "oil yield" and "volatility" of thermal conductive silicone esters should be considered when selecting the type of silicone oil. The poor quality of thermal conductive silicone esters will precipitate silicone oil at the working temperature of LED (some worse can be opened to the surface of a layer of transparent silicone oil); with glue (silicone / epoxy / acrylic acid structural adhesive can be used) to seal and bond. .
Attention should be paid to wait for the glue to be completely cured before aging on the aging shelf burning machine aging, glue not fully cured in the case of heat will be volatile possibility, may appear bubble shell cracking and other phenomena. Silica gel is the most common used in LED lighting industry for the cover of bulb, candle and panel lamps. Its curing mechanism is based on the cross-linking reaction of regenerative vulcanization by absorbing water in the air, and by-products are produced at the same time. According to the by-products are divided into deacidification type, oxime type, dealcoholization type, the larger the molecular weight of the small molecule is, the easier it is to come out in liquid form, adhere to the inner wall of the outer cover to form water mist. Molecular weight: acid > oxime > alcohol, so in the selection of the time to choose the type of alcohol through quantitative dispensing, control the best dispensing amount, volatile matter on the impact of lamps to the minimum.
The small molecular substances in the cured glue will also evaporate at high temperatures, forming a layer of mist on the mask, which will affect the appearance and brightness of lamps. Common small molecule substances are mainly divided into low molecular cyclosiloxane and low molecular atomization packaging molecules, generally using the total amount of D8-D10 to express the level of small molecule content.
The test method for low molecular polysiloxane is gas chromatography-mass spectrometry. In general, the content of low molecular polysiloxane in silica gel must be strictly controlled on PCB boards for sealing, sealing, sealing and sealing of electrical, electronic, communication, instrumentation and optical components used in aviation and astronautics, as insulation, shock-proof, moisture-proof and conductive links. Or pollution.