Small packaging, big future, the essence and future interpretation of CSP LED

CSP is only a form of encapsulation

All the time, the industry has misconceptions about CSP itself. The full name of CSP is Chip Scale Package, which means chip level packaging device in chinese. It uses the IPC standard J-STD-012 definition of CSP packaging, refers to the package size and chip size than no more than 1.2 times the function of the complete package device. As far as CSP is concerned, it does not mean low cost, nor does it mean how superior CSP is in performance, nor does it mean what kind of traditional packaging life CSP needs and so on. CSP is just a form of encapsulation, similar to SMD. To discuss the CSP cost advantage, must have a combination of CSP package and the benefits of CSP package in specific applications can bring new functions can bring new added value to the end user.

At present, the mainstream structure of CSPLED can be divided into substrate and non substrate, and can be divided into five sides, light-emitting and single-sided light-emitting. The substrate can naturally be considered as a scaffold. Obviously, in order to meet the CSP requirements for packaging size, the traditional stent, such as 2835, can not be used, but does not mean that CSPLED stents, in fact, CSPLED using the substrate cost is much higher than SMD. Subject to size, CSPLED usually cannot use chips that require solder wires, such as on chip or vertical chips, which can only be flip chip or flip chip.

In terms of the manufacturing cost of the chip itself, the price of flip chip is always larger than that of the fixed chip chip in a short period of time, considering the effect of scale. The flip chip high precision chip facing CSPLED welding or arrangement, fluorescent powder glue spraying, membrane pressure, molding or dam in dispensing, coating, cutting LED spectrophotometer, and woven bags, its technical content, process complexity, and equipment requirements is not easier than traditional packaging industry cheap and mature.

Based on the above analysis, we can conclude that (1) CSP is only a package device in the field of LED applications, can be regarded as a brand new product form different from SMD. (2) CSPLED has not yet established a mature process route, equipment conditions, and no mainstream packaging structure has been formed. (3) no matter what method is adopted, the lumen cost of CSPLED can not be lower than that of the traditional chip LED and the traditional 2835.

CSP LED must be the mainstream product of the future

Can CSPLED become a mainstream product in the future? The conclusion is in the affirmative, but must be closely around the characteristics CSPLED to CSPLED performance, user experience and value added, otherwise, in a short period of time, the size of application CSPLED will be affected by the manufacturing cost according to not under the restriction of high.

CSPLED is characterized by small size, high current and high reliability. In order to achieve the small size, high current, high reliability, CSPLEDs should be provided with a ceramic substrate, such as stereo full package five surface emitting CSPLED Shenzhen Avenue Semiconductor Co. Ltd. using ceramic substrate + flip chip manufacturing (as shown in Figure 1) and the ceramic substrate and thin film flip chip manufacturing pure single light emitting CSPLEDs (e.g. as shown in Figure two).

Figure 1: stereo full package five surface emitting CSPLED + ceramic substrate flip chip manufacturing (from Shenzhen Avenue Semiconductor Co. Ltd., yellow fluorescent glue, blue flip chip, red pad, gray represents a ceramic substrate)

Figure two: ceramic substrate and thin film flip chip manufacturing pure single light emitting CSPLEDs (from Shenzhen Avenue Semiconductor Co. Ltd., yellow fluorescent glue, brown for thin film flip chip, white and white walls, red represents pad, gray represents a ceramic substrate)

Compared with CSPLED without ceramic substrate, CSPLED with ceramic substrate has the following characteristics: (1) compatibility with standard SMT, reflow soldering quality, high yield and low cost. (2) strong thermal shock resistance and high current impact capability. (3) the fluorescent adhesive is firm and is not easy to cause the blue light to leak out due to the expansion and contraction when the super drive is used and the drop caused by the touch and collision of the outside. (4) in addition to the back pad, there is no exposed silver layer in the whole structure. Compared with the traditional packaging form, it has better anti halogenated, anti vulcanizing ability, as well as heat resistance, humidity resistance, moisture resistance.

The three-dimensional full package five surface emitting CSPLED with ceramic substrate and thin film flip chip manufacturing pure single emitting CSPLEDs compared with ceramic substrate + flip chip manufacturing, the former light angle, the light angle is small, high brightness, projection distance; the former because the four corner square with positive light intensity and fluorescent powder rubber coating will lead to uneven spatial color uniformity is poor, the positive side light, no pad dark, no blue yellow core area, spatial color uniformity; the former because of the flip chip substrate still exists, the rubber surface temperature is higher than the latter, which can bear larger driving current the.

Based on the above, with small size, high current and high reliability for the characteristics of the CSPLED is not suitable for floodlighting, is suitable for the light source, and projection distance, light angle, illumination and other requirements of the direction of the center of projection lighting field, such as back light, flash, projector, light lighting (the lights, searchlights, flashlight, work lights, outdoor lights, high roof landscape), small angle lighting etc.. (author: Shenzhen Avenue Semiconductor Co., Ltd. Li Gang)

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