Manufacturing method for semiconductor light emitting device

The present invention relates to a method for manufacturing a semiconductor light emitting device, and more particularly to a method for manufacturing a surface mount type semiconductor light emitting device using a lead frame.

Light emitting diodes (LEDs) can be roughly classified into two types depending on the mounting method when mounting on a printed circuit board. One type is to insert a lead frame with an LED chip into the through hole of the double-sided through hole printed circuit board and fix it by soldering from the opposite side of the printed circuit board. The other type is to place the LED on the printed circuit board. The electrodes are soldered and fixed to the circuit conductor pattern formed on the same surface.

The latter is called a surface mount type LED, and is a semiconductor light emitting device that contributes to cost reduction because a printed circuit board having a circuit conductor pattern on only one side can be adopted. In general, the size has been significantly reduced compared to the former, and nowadays, light sources for lighting such as liquid crystal and numeric keypad that make up small devices such as mobile phones and PDAs, auxiliary light sources for camera-equipped mobile phones, and light sources for strobes. Etc. are used.

In addition, the structure of surface mount type LEDs can be roughly divided into two types. One type is by fixing (die bonding) the LED chip to the circuit conductor pattern formed on the printed circuit board by a bonding method such as eutectic bonding or solder bonding. An electrical conduction between the lower electrode of the LED chip and the circuit conductor pattern is achieved, and the circuit conductor pattern separated from the upper electrode of the LED chip and the circuit conductor pattern to which the LED chip is fixed is connected via a bonding wire (wire). Electrical conduction is achieved by bonding), and the LED chip and bonding wire are sealed with a translucent resin to protect the LED chip from the external environment such as moisture, dust and gas, and the bonding wire is vibrated and bonded. It is protected from mechanical stress such as impact.

In the other type, a substantially flat lead frame is embedded in a lamp house made of a non-translucent resin having a high reflectance in which a bowl-shaped recess is formed, and integrally formed to form a package. By die-bonding the LED chip to the lead frame exposed at the bottom of the recess of the house by a bonding method such as eutectic bonding or solder bonding, electrical conduction between the electrode below the LED chip and the lead frame is achieved, and the LED chip By wire bonding the lead frame separated from the lead frame to which the upper electrode and the LED chip are die-bonded, they are connected via a bonding wire to achieve electrical conduction, and the recess is filled with a translucent resin. The LED chip and bonding wire are sealed with.

The latter conventional method for manufacturing a surface mount LED is a step of molding the lead frames 31a and 31b of FIGS. 6 (a) and 7 (a), and molding of FIGS. 6 (b) and 7 (b). The lead frames 31a and 31b are embedded and set in the mold 32, and a highly reflective non-transmissive resin is press-fitted into the cavity 40 to form a package 34 in which the lead frames 31a and 31b and the lamp house 33 are integrally formed. Process, a die bonding process in which the LED chip 36 is mounted on the lead frame 31a at the bottom of the recess 35 formed in the lamp house 33 of the package of FIGS. 6 (c) and 7 (c) via the joining member 39. The wire bonding process of connecting the upper electrode of the die-bonded LED chip 36 of 6 (d) and FIG. 7 (d) and the lead frame 31b with a bonding wire 37, of the packages of FIGS. 6 (e) and 7 (e). The steps of filling the recess 35 of the lamp house 33 with the translucent resin 38 and curing it to seal the LED chip 36 and the bonding wire 37, the lead frames 31a and 31b of FIGS. 6 (f) and 7 (f). It is manufactured through a process of cutting and forming in sequence (see, for example, Patent Document 1).<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2002-249769</text></patcit>

<p> However, the conventional surface mount LED manufacturing method described above comprises a non-transmissive resin of the package under a high temperature environment when the LED chip is die-bonded to the lead frame by a bonding method such as eutectic bonding or solder bonding. It has a problem that the lamp house is easily deformed or burnt.</p><p> On the other hand, in order to avoid this problem, it is conceivable to use a non-transmissive resin that can withstand a high temperature environment during eutectic bonding or solder bonding as a material for forming a lamp house, but in that case, it is adopted. The selection range of the resin is limited, and even a non-transmissive resin with high reflectance may not be adopted due to its low heat resistance, and as a result, it is possible to create a product with excellent optical characteristics that satisfies it. You will not be able to.</p><p> Therefore, it cannot be said that the conventional method for manufacturing a surface mount type LED is a suitable method for die bonding an LED chip to a lead frame by a bonding method such as eutectic bonding or solder bonding.</p><p> Therefore, the present invention has been devised in view of the above problems, and provides a method for manufacturing a surface mount type LED having high light utilization efficiency and high brightness.</p>

<p> In order to solve the above problems, in the invention described in claim 1 of the present invention, a semiconductor light emitting element is die-bonded to a lead frame arranged at the bottom of a bowl-shaped recess provided in a lamp house, and the semiconductor is said. A lead frame arranged at the bottom of the recess separated from the electrode provided in the light emitting element and the lead frame to which the semiconductor light emitting element is die-bonded is connected by a bonding wire, and the translucency filled in the recess is filled. A method for manufacturing a semiconductor light emitting device in which the semiconductor light emitting element and the bonding wire are sealed with a resin, wherein the semiconductor light emitting element is die-bonded to the lead frame in the first step of forming the lead frame. A lead frame in which the second step, the third step of integrally forming the lead frame and the lamp house, and the lead frame in which the electrodes provided on the semiconductor light emitting element and the semiconductor light emitting element are die-bonded are separated. It is characterized by having a fourth step of wire bonding to connect the semiconductor light emitting element and the bonding wire via a bonding wire, and a fifth step of sealing the semiconductor light emitting element and the bonding wire with a translucent resin. is there.</p><p> Further, in the invention described in claim 2 of the present invention, in the third step of claim 1, the semiconductor light emitting device die-bonded to the lead frame is not buried in the molding material forming the lamp house. As described above, the semiconductor light emitting device is provided with protective means so as not to be contaminated by the gas generated from the molding material.</p><p> The invention according to claim 3 of the present invention is characterized in that, in any one of claims 1 or 2, the protective means forms a closed space including the semiconductor light emitting device. It is something to do.</p>

<p> By integrally forming the lead frame and the lamp house after mounting the semiconductor light emitting element on the lead frame, the lamp house is not exposed to the high temperature environment when the semiconductor light emitting element is mounted on the lead frame. There is an advantage that a molding material having a high reflectance for forming the above can be selected and adopted without being restricted by high heat resistance.</p>

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 5 (the same parts are designated by the same reference numerals). Since the embodiments described below are suitable specific examples of the present invention, various technically preferable limitations are added, but the scope of the present invention particularly limits the present invention in the following description. Unless otherwise stated, the present invention is not limited to these aspects.

FIG. 1 is a process flowchart relating to the method for manufacturing the semiconductor light emitting device of the present invention, and FIG. 2 is a process diagram also relating to the method for manufacturing the semiconductor light emitting device. Hereinafter, the manufacturing process will be described in detail while comparing FIGS. 1 and 2.

First, as shown in FIG. 1 (a), it is a step of forming a lead frame. As described above, the surface mount type LED of the present invention is becoming smaller, and as an example of the present situation, there is a product that has a size of about 3 mm in both length and width and a height of about 2 mm. In most cases, such small parts are mass-produced in bulk by flowing them in a state of taking a large number of parts instead of flowing the manufacturing process from the start of mass production to the completion in units of one piece.

Therefore, even in the lead frame, a single metal plate made of copper, iron, 42 alloy material, etc. is formed into a desired shape by press punching or etching method so that a large number of LED chips can be mounted, and gold plating and Surface treatment such as silver plating is performed to form lead frames 1a and 1b as shown in FIG. 2 (a).

Next is the die bonding step shown in FIG. 1 (b). As shown in Fig. 2 (b), the LED chip 2 is fixed to the lead frame 1a by a bonding method such as eutectic bonding or solder bonding in a high temperature environment, and at the same time, the lower electrode and lead frame of the LED chip 2 are fixed. Electrical conduction between 1a and 1a is achieved via the joining member 3.

Next is the package molding step shown in FIG. 1 (c). This is generally performed by injection molding, and as shown in FIG. 2 (c), the lead frames 1a and 1b are used as inserts, and the surface of the lead frame 1a on which the LED chip 2 is mounted is used as the parting surface 4. When inserted into one multi-cavity mold 5 and sealed, the cavity 6 is formed in the two molds 5, and the LED chip 2 mounted on the lead frame 1a is prevented from being buried in the molding material, and the molding material. The two molds 5 and the lead frame 1a form an enclosed space 7 containing the LED chip 2 so as not to be contaminated by the gas generated from the LED chip 2.

Then, when the insert is inserted and a non-transmissive resin having high reflectance as a molding material is press-fitted into the cavity 6 of the mold 5 for which the setting is completed to be solidified, and then the molded product is taken out from the mold 5. Package 8 of the semiconductor light emitting device as shown in Fig. 2 (c) is completed.

The lamp house 9 formed of the highly reflective non-transmissive resin of the package 8 of the semiconductor light emitting device has a bowl-shaped recess 10 in which the LED chip 2 is arranged at the bottom, and the inner peripheral surface thereof is the reflecting surface 11. Is formed. The surfaces of the lead frames 1a and 1b located at the bottom of the recess 10 are exposed to the atmosphere, and there is nothing to cover the surface.

Next is the wire bonding step shown in FIG. 1 (d). As shown in FIG. 2D, the upper electrode of the LED chip 2 and the lead frame 1b separated from the lead frame 1a on which the LED chip 2 is mounted are exposed at the bottom of the recess 10 of the lamp house 9. Are connected by a thin bonding wire 12 mainly composed of gold or aluminum to achieve electrical continuity between the two.

Next is the sealing / curing process shown in Fig. 1 (e). As shown in FIG. 2 (e), the recess 10 formed in the lamp house 9 is filled with a translucent resin 13 made of epoxy resin or silicone resin to seal the LED chip 2 and the bonding wire 12. , Cure.

One of the purposes of sealing the LED chip 2 and the bonding wire 12 with the translucent resin 13 is to protect the LED chip 2 from the external environment such as moisture, gas and dust, and to mechanically protect the bonding wire 12 from vibrations and shocks. It is to protect from stress.

Similarly, one of the purposes is to refract the translucent resin 13 made of epoxy resin or silicone resin close to the refractive index of the semiconductor material constituting the light emitting surface 14 of the LED chip 2 forming an interface with the translucent resin 13. Select and adopt from those with a rate. Then, of the light emitted in the LED chip 2, the light that is totally reflected by the light emitting surface 14 of the LED chip 2 and returned to the inside of the LED chip 2 is minimized, and as much light as possible is emitted from the light emitting surface of the LED chip 2. This is because the light extraction efficiency from the LED chip 2 can be improved by incident light into the translucent resin 13 forming the interface from 14.

The final step is the cut forming process shown in Fig. 1 (f). In this method, the lead frames 1a and 1b of a large number of semiconductor light emitting devices connected by the lead frames 1a and 1b are cut and separated into individual semiconductor light emitting devices, and the lead frames 1a and 1b are formed into a desired shape. Is. FIG. 2 (f) is a cross-sectional view of the semiconductor light emitting device completed by forming the lead frame, and FIG. 3 is a top view of FIG. 2 (f).

The effect of using a high-reflectivity member for the resin forming the lamp house is that the light emitted from the semiconductor light emitting element, which is directed toward the inner peripheral surface of the bowl-shaped recess formed in the lamp house, is the inner circumference. It reflects on the reflective surface formed on the surface and directs it toward the radiation direction of the semiconductor light emitting device, and enhances the light extraction efficiency and the light utilization efficiency by the condensing effect, and realizes high brightness as a light source. Therefore, the higher the reflectance of the inner peripheral surface of the recess, the higher the brightness of the light source becomes.

Fig. 4 shows an excerpt of the process of forming a bowl-shaped recess with the inner peripheral surface as the reflective surface in the lead frame and putting it into the manufacturing process to complete the semiconductor light emitting device. a) is a cross-sectional view showing the shape of the molded lead frame, (b) is a cross-sectional view showing a state in which a lead frame equipped with a semiconductor light emitting element is set in a mold, and (c) is a cross-sectional view of a finished product. Further, FIG. 5 is a top view of the finished product of FIG. 4 (c). Since the manufacturing process from the insertion of the lead frame to the finished product is the same as above, some process diagrams from all the processes are shown with symbols, and at the same time, the explanations of the processes are duplicated. So omit it.

In this case, the reflective surface 16 formed on the inner peripheral surface of the concave portion 15 of the lead frame and the reflective surface 11 formed on the inner peripheral surface of the concave portion 10 of the lamp house 9 are formed in two layers, and the reflective surface is one-stage. The probability of being reflected by the reflecting surface is higher than in some cases, and the light extraction efficiency and the light utilization efficiency are increased accordingly, leading to higher brightness of the light source.

Further, when the lead frames 1a and 1b and the lamp house 9 are integrally formed, the semiconductor light emitting element 2 included in the sealed space 7 can be secured by covering the recess 15 of the lead frame 1a with the mold 5. It can be reliably protected from the resin and the gas generated from the resin. Further, by forming the end surface 17 of the mold 5 on a flat surface, the sealed space 7 can be surely secured, so that the manufacturing cost of the mold can be reduced, and as a result, the product cost can also be reduced.

Next, the effect of the method for manufacturing the semiconductor light emitting device of the present invention will be described. First, a lead frame in which a semiconductor light emitting element is die-bonded is integrally formed with a lamp house made of a non-transmissive resin. In other words, the semiconductor light emitting element was die-bonded to the lead frame before the lead frame was integrally formed with the lamp house made of a non-transmissive resin. As a result, the lamp house made of a non-transmissive resin is not exposed to a high temperature environment when the semiconductor light emitting element is die-bonded to the lead frame by a bonding method such as eutectic bonding or solder bonding. Therefore, the selection range of the resin used for the lamp house is not restricted by the bonding temperature, and even a resin having a high reflectance having a heat resistant temperature lower than the bonding temperature is adopted as a resin for forming the lamp house. Therefore, it is possible to realize a high-luminance semiconductor light emitting device having high light extraction efficiency and light utilization efficiency.

As a matter of course, since the temperature at the time of joining the semiconductor light emitting element and the lead frame is not applied to the lamp house, the lamp house is not deformed or burnt, and a high quality product can be finished. It has an excellent effect such as.

<figref num="1">It is a flowchart which shows the embodiment which concerns on the manufacturing method of the semiconductor light emitting device of this invention.</figref><figref num="2">It is a process drawing which shows the embodiment which concerns on the manufacturing method of the semiconductor light emitting device of this invention.</figref><figref num="3">It is a top view of FIG. 2 (f).</figref><figref num="4">When another lead frame according to the method for manufacturing the semiconductor light emitting device of the present invention is used, (a) is a cross-sectional view of the lead frame, (b) is a cross-sectional view when the mold is set, and (c) is a cross-sectional view of the finished product. It is a figure.</figref><figref num="5">It is a top view of FIG. 5 (c).</figref><figref num="6">It is a flowchart concerning the manufacturing method of the conventional semiconductor light emitting device.</figref><figref num="7">It is a process drawing which concerns on the manufacturing method of the conventional semiconductor light emitting device.</figref>

Code description

1a, 1b Lead frame 2 LED chip 3 Joining member 4 Parting men 5 Mold 6 Cavity 7 Sealed space 8 Package 9 Lamp house 10 Recessed 11 Reflective surface 12 Bonding wire 13 Translucent resin 14 Light emitting surface 15 Recessed 16 Reflective surface 17 End face