Japanese-Asian flip-chip products, TSMC flip-chip modules and flip-chip LED analysis

The biggest news of Japan this year is not to promote any products, but the former Japanese employee, Nakamura Shuji, won the 2014 Nobel Prize in Physics. From a small company to a leader in the LED industry, employees in Niya-mura in Japan are undoubtedly lucky. He brought to Japan's blue LED technology with core technology, which has played a leading role in the development of the industry.

Technical route: The sapphire substrate is loaded with chips and low power. Medium power and high power are made from many small power products.

Product Route: The world's first company to add EMC materials to packaged racks. From the previous 157 series 3014 package, Nichia has sealed two small chips in series to achieve 6V. At the same time, the 3014 product is only driven to 30mA, 0.1W, and Nichia's products can already achieve 0.5W drive power. Nowadays, major manufacturers are promoting large-scale flip-chip CSP products. Nichia also started to promote the T02A series products this year. Although it is not a CSP, it uses a flip chip, and the package form is also a way of emitting CSP at a large angle. Let's unveil the veil of Nichia T02A.

Official data of Nichia: Product size: 1.2mm*0.7mm; Specifications: 0.2W, 3V, 22lm@60mA, what is the actual test?

After dragging through the actual test data, the official publicity data is true. Is it a dressing chip or a flip chip?

Seen from the side view, the package is to fix the chip on a flat BT board and mold the fluorescent glue.

Peeling off the fluorescent adhesive layer, exposed on the outside is a flip chip without gold wire. By measuring the size, the chip size is about 12*30mil. The domestic chip of this size has recommended customers to use 120mA, the official of Nichia. It is only recommended to use 60mA, it can be seen that Nichia's use of flip chip is still conservative. If it is a formal chip, the size of this size Nichia should be 150mA, and the same light output can be guaranteed.

The die-bonding method of flip chip has always been the focus of domestic discussions. Some companies recommend solder paste. Some companies recommend silver paste. Some companies use metal processing on the die pad to solder by eutectic. If it is from the firmness of soldering, eutectic is the best. The solder paste is second, and the silver paste is the worst. Then, let's see how this flip-chip product from Nichia is soldered. The T02A was placed on a heating table, heated at 260°, and the chip was removed.

The above figure is left on the substrate. Through this figure, it is found that the first is not silver glue, and secondly it is not eutectic. Is it solder paste? It should be solder ball soldering. The tiny solder balls are placed in a fixed position and can be soldered by heating, which is already a mature supply in conventional semiconductor soldering. It can avoid the flux volatilization caused by the use of solder paste, which is stronger than the silver glue soldering, and the solder ball can form a connection with the upper and lower interfaces at the high temperature state.

Nichia recommends the use of this product: large angle bulbs and tube lights. With an LED of about 0.2W, it is indeed possible to form a high-angle light source product that is well arranged to realize a large-angle bulb and tube lamp. It is only because the light efficiency of its own products is not high, it will be limited in the use of products with high light efficiency requirements. In the positioning of this product, Nichia continued their idea of ​​designing the main line with medium and small power. Just using such a large chip, it is recommended that the current of 60mA is Nichia's distrust of flipping? Compared with the characteristics of the high-efficiency of flip-chips on the major websites, why did Japan's flip-chips fail to achieve high light efficiency? The reason remains to be discussed by the same industry.

As a leading company in traditional semiconductor manufacturing, TSMC is not smooth on the road to the LED market. From the previous pick to the current TSMC, from high-power LEDs to the current flip-chip PoD products, from the brand promotion point of view, it is not very successful.

Now the market has received feedback on some PoD products. Each company has its own ideas and opinions, and cannot use the module products of the production enterprises. It is also for this reason that the sales of the main push module companies are not good. Although the marketing of PoD module products is not good, there are many places that TSMC can introduce, and it is worth learning from the boss of traditional semiconductors.

This module uses a universal hexagonal substrate design that meets the habits of most lighting companies. It adopts 4 inverted products in series with an operating voltage of 12V. It is recommended to use a rated current of 500mA and a maximum current of 700mA. However, by considering its photoelectric parameters, 400mA has no high light efficiency, and the risk is high under high current conditions.

Since it uses a flip chip, the voltage volatility is much better than the chip.

The thermal resistance indicated in the specification is 2.3°/W, which is still relatively low compared to the thermal resistance of the formal product. The anti-static ability ESD indicated in the specification is 2000V for human body mode, which is relatively low. It may be necessary to pay special attention to the problem of static protection when using a similar flip-chip product module.

For such a flip-chip module, one of the reasons for TSMC to promote the module is that if the single product is promoted in the market, the customer is not good at the patch end. So let's see what the patch is like?

Through the side view of the module, the flip-chip product has no substrate and is a standard CSP package mode. By measuring the dimensions of several front faces, it is found that the shape is regular. Corresponding to a traditional semiconductor company such as TSMC, the CSP class packaging is its advantage (just as the domestic Changjiang Electronics Technology claims to develop CSP LED package devices. This is very normal, the traditional semiconductor itself has CSP package devices).

By removing the device, it was found that the CSP lamp bead pad has a double E shape, and the pad has good tin soldering, which fully demonstrates that TSMC has a lot of work on the pad material. The phosphor coating is uniform, which avoids the phenomenon of blue light leakage on the side. This packaging process is worth learning for all our LED companies. The chip area is about 45*45mil, which may be a bit higher if it is 500mA as recommended in its specification. Such a module was originally defined for use on MR116 or GU10 products, and a corresponding lens positioning seat is also provided on the substrate. By using the recommended lens, the spot effect is also OK. Only the overall luminous flux is not enough, and the flip-chip products still need more improvement and efforts. The MR16 product replaces the traditional metal halide lamp, and has clear requirements for luminous flux, illuminating angle and illuminance, and is currently a relatively high added value product.

The problems encountered in the promotion of modules are similar to those encountered in COB products. Every lighting company wants to have its own specifications, which leads to too many specifications of device suppliers, which is not conducive to product promotion and interchangeability. Although Zhaga promoted the standard module for several years, the effect is still not obvious. For luminaires, there are many products with different specifications and shapes, and there are many kinds of corresponding light sources. Whether the flip-chip product is to be a module or a single discrete device needs to be verified by the market.

After the module promotion did not see the future and the bright future, TSMC actively adjusted and introduced a TP1E made by flip chip. What kind of things can this product bring to us? What other characteristics are destined for its fate?

From the appearance, this is a product with a large flow, 1.6mm * 1.6mm size, the substrate is made of ceramic, the phosphor is directly coated. There is not much difference from the products circulating in the market. Let's take a look at the official introduction.

It can be seen from the official introduction that with a light angle of 150°, it can achieve higher light output in a smaller size, which is the application and characteristics given by TSMC. If you look at the application of the luminaire, the requirements of the high-power spotlights for the light source meet the above requirements. Smaller sizes are indeed more advantageous for optical design, but such large angles of light flux are more difficult to collect.

Fortunately get samples and see the actual test data:

The actual test ambient temperature is 25 ° C, and the official data is slightly lower. From the fluctuation of the voltage, this voltage has a very large influence on the solid crystal process as the voltage changes little with the increase of the current. What is the way to flip-chip this flip chip? Only know when you open it. First look at the detailed appearance:

The right side of the side is slightly missing. From the TSMC module to the release of this single product, the packaging process may be covered with a fluorescent tape similar to tape, and then cut after baking. The process precision is controlled by the precision of the cutting machine.

From the side, the phosphor thickness is thicker and the lines on each side are flat. It was again verified that its shape was formed by cutting.

The design on the bottom pad is notched and is the indication of the negative direction. The ceramic substrate may be made by through-hole filling technology for electrical performance conduction.

Through the violent means of the phosphor on the glass, the appearance of the flip chip is exposed. No shape of silver paste or solder paste was seen at the bottom of the chip, and eutectic soldering was preliminarily inferred.

Viewed by the side of the chip, the solder layer is very thin and there is no spillage. Then push the chip off the bracket, the resistance is very large, it is estimated that the force of about 700~1000 is estimated to push the chip down. Confirmed as a eutectic soldering process, the eutectic technology is also the advantage of traditional semiconductors. Compared with the dressing products, this product may have higher quality stability. Without gold wire, eutectic soldering is not easy to open. The improvement of luminous flux is still a top priority, and the quality stability of light color needs long-term verification to be seen. I hope that the leader of traditional semiconductors can make better products by combining their own advantages in the field of LED lighting.

Corresponding to the CSP packaging products, the products of Samsung, Nichia, TSMC and other companies are analyzed. The common point is that the luminous flux is not high, which leads to low cost performance. CSPs can make a fuss about higher light color quality, with a focus on automotive lighting, commercial lighting, stage lighting, or Projector Light sources. Not all products should meet the needs of the general market, and it is completely unnecessary. Finding differences, subdividing, and profits are naturally high.