CN1396667A - LED packaging - Google Patents

Abstract

The invention takes a silicon wafer as a substrate, wet etching is carried out by utilizing the crystal face of the silicon wafer to form a groove, a through hole electrode is manufactured by utilizing dry etching on the back face of the silicon substrate, an insulated gasification film layer or a nitride film layer is formed by utilizing the silicon face, then a reflecting layer and an electrode layer are plated, a light emitting diode crystal grain is placed in the groove of the silicon substrate, and the steps of crystal fixing, routing, sealing, cutting and the like are carried out, thus forming the SMD light emitting diode finished product. The invention has the advantages of good heat dissipation, high temperature resistance, miniaturization and the like.

Description

LED packaging

technical field

The invention belongs to a sealing of a light-emitting diode, in particular to a sealing of an adhesive type light-emitting diode.

Background technique

At present, the packaging of surface mount light-emitting diodes (SMD LEDs) is mainly divided into two types: circuit board type and bracket type. The bracket type SMD LED uses a metal bracket as the substrate and then seals it by injecting plastic grooves or molding. Glue and cut to form SMD type LED as shown in Figure 1. The circuit board type SMD LED uses a composite material circuit board as the substrate and then seals it with molding (molding) and cuts it to form an SMD type LED, as shown in Figure 2. At present, the SMD LEDs produced by these two methods have Some common disadvantages, one is that the temperature resistance is not enough, especially when SMD components are bonded to other circuit boards, they must pass through a high temperature furnace (about 250-300 ° C), the molding sealant of SMD LEDs has insufficient temperature resistance, and the general sealant Tg The temperature is only about 120°C and the coefficient of thermal expansion is different from that of the substrate or bracket, because abnormal defects often occur after the SMD LED component is overheated in the furnace; another disadvantage is poor heat dissipation, and the heat transfer between the sealing material and the substrate is not good. , and the LED component itself is also a small heating body. When the heat dissipation is not good, the increase in temperature rise will affect the luminous efficiency and quality of the component; another disadvantage is that the reflection groove is not easy to make when it is miniaturized. There is more than double the difference in brightness between those with reflective grooves and those without reflective grooves (based on a light-emitting angle of 30 degrees). It is basically difficult to make reflective cups with grooves in traditional manufacturing processes.

Poor temperature resistance, poor heat dissipation, and difficulty in making miniaturized reflective grooves are the biggest problems of traditional SMD LEDs.

Contents of the invention

The object of the present invention is to provide a light-emitting diode enclosure, which has the advantages of high heat resistance, easy manufacture of reverse grooves, good heat dissipation, and easy miniaturization.

In order to achieve the above object, the present invention provides a light-emitting diode package, which uses wet etching to etch a groove reflective seat with inclined walls after the photoresist layer on the front side of the silicon wafer substrate is exposed and developed; The photoresist layer is also applied on the back side of the groove, and the electrode hole pattern is provided at the opposite position of the bottom of the groove. After exposure and development, the through hole electrode hole is etched out by etching, and then the photoresist is removed, and then the silicon wafer substrate is oxidized in a high temperature furnace. Or nitriding treatment to form a layer of silicon oxide or silicon nitride insulating layer on the surface of the silicon substrate, and then use electroplating to coat the front and back of the silicon substrate and the inside of the through-hole electrode hole with a metal conductive layer, and use laser processing to The electrode surface in the groove is divided into electrode contact surfaces with positive and negative electrodes, so as to facilitate the placement of LED light-emitting crystal grains and bonding with the electrodes.

Among them, the metal-plated conductive layer must have both conductive and light-reflective functions, and its materials are Ag, Au, Pd, pt, etc.

Wherein the silicon wafer substrate selects the silicon wafer with 100 crystal orientations to etch grooves with inclined walls.

Wherein the silicon wafer substrate uses the silicon wafer with 110 crystal orientation to etch grooves with vertical walls.

When the wet etching solution is alkaline (potassium hydroxide KOH), the photoresist must be developed with acid.

The silicon wafer substrate is heated by a nitrogen high-temperature furnace to form a silicon nitride layer on the surface of the silicon wafer, and then a photoresist is applied to expose and develop with a photomask, and the silicon nitride layer in the development area is removed by reactive ion etching (RIE). Then wet etching is used to etch out the structure with grooves; on the back of the silicon wafer substrate, a photoresist is placed on the back of the silicon wafer substrate and an electrode hole pattern is provided at the relative position of the groove with the mask for exposure and development, and then reactive ion etching (RIE ) to remove the silicon nitride layer, use dry etching inductively coupled plasma (ICP) to make the through-hole electrode hole, and oxidize or nitride the silicon wafer substrate to form an insulating layer on the inner wall of the groove and the through-hole electrode hole, Then the silicon substrate is plated with a metal layer, and the positive and negative electrode surfaces in the groove are divided by laser processing, so that the LED crystal grains can be placed in the groove and bonded with the electrodes.

Place the LED light-emitting crystal grains in the groove of the silicon wafer substrate with a groove reflector, connect the positive and negative electrodes of the LED light-emitting crystal grains to the positive and negative electrodes of the silicon wafer substrate groove, and cover the LED with sealing resin The light-emitting crystal grains fill the entire groove, and the encapsulant resin is cured by heating and then cut into granular surface-mounted light-emitting diode elements.

The sealing resin is a transparent high temperature resistant silicone or epoxy resin (EPOXY)

The wafer substrate may be a silicon wafer (Si) or a silicon dioxide (SiO ₂ ) wafer substrate.

Wherein the sealing resin is formed by molding to form a structure with a convex lens function on the surface.

Wherein, more than two LED crystal grains can be placed in the single groove reflective seat of the wafer substrate at the same time.

The fabrication process of light-emitting diode (LED) silicon substrate is as follows (A)

1. First choose a silicon wafer (6 inches) with a crystal orientation of 100 (Orientation);

2. Apply photoresist and remove unnecessary photoresist by exposure and development;

3. Utilize Anisotropic wet etching (Anisotropic wet etching), etch to a certain depth, that is, form a groove (reflector seat) with an inclination angle of 54.74°;

4. Through-hole electrode holes are made by dry etching or laser processing on the back of the silicon wafer;

5. After oxidation or nitriding treatment, an insulating silicon oxide layer (SiO ₂ ) or silicon nitride layer (Si ₃ N ₄ ) is formed on the surface;

6. Metal plating layer (silver plating, including groove reflective layer and back electrode layer);

7. Use laser (Nd-YAG) to process the electrodes in the divided groove to form both ends of the positive and negative electrode surfaces.

Potassium hydroxide is mostly used for etching grooves on silicon substrates, especially for wet etching silicon materials. When using alkaline potassium hydroxide (KOH) for etching, if ordinary photoresist is used, the photoresist will be eroded by KOH, so special light must be used. The resist is the photoresist developed with acid (this kind of photoresist is not easy to buy in the market). If a general photoresist is used to etch a silicon substrate, another process (B) must be used instead.

Light-emitting diode (LED) silicon substrate manufacturing process (B):

1. Use a silicon wafer with 100 crystal orientations;

2. Send it to a nitrogen high-temperature furnace for heating to form a silicon nitride layer (Si ₃ N ₄ ) on the surface of the silicon wafer;

3. Apply photoresist and expose and develop;

4. Use reactive ion etching (RIE) to remove the Si ₃ N ₄ layer (also known as hard mask) (also known as window opening);

5. Using wet etching solution (KOH) to etch out a structure with grooves;

6. Apply photoresist on the back of the silicon wafer and expose and develop;

7. Remove the Si ₃ N ₄ layer by RIE plasma etching;

8. Then use inductively coupled plasma (ICP) for dry etching to make through-hole electrode holes;

9. The silicon wafer is oxidized or nitrided to form an insulating film on the surface of the groove and the through hole;

10. Plating metal layer;

11. Use laser processing to cut out the positive and negative electrode surfaces in the groove.

The biggest difference between process B and process A is that process B uses general photoresist, and process A uses acid-developed photoresist. Process B must first grow a layer of Si ₃ N ₄ film and then use RIE plasma to etch this layer (RIE etches silicon (Si) at a very slow speed, and ICP must be used to etch silicon when dry etching silicon).

The above steps complete the basic process method of the special silicon substrate for the packaging of SMD light-emitting diodes of the present invention. The etching depth of the silicon substrate in the 100 crystalline orientation is not vertically downward but forms a groove with an inclination angle of 54.74° by wet etching. This angle is just right. Suitable for emission angle of SMD LED. The silicon substrate with a crystal orientation of 110 is wet-etched to a depth of a vertical wall, and the grooves formed can also be applied to small-angle SMD LED components.

The LED chip (Chip) is solidified in the groove of the silicon substrate, wired, dispensed, and cut into SMD-type LED particles, and the SMD-type LED device with the silicon wafer as the substrate is completed.

Description of drawings

In order to have a further understanding of the present invention, the following examples are given, and are illustrated as follows, wherein:

FIG. 1 is a cross-sectional view of a package structure of a traditional metal bracket type SMD light emitting diode.

Fig. 2 is a cross-sectional view of a packaging structure of a traditional circuit board type SMD light emitting diode.

Fig. 3 is a cross-sectional view of the silicon substrate of the package of the light emitting diode of the present invention.

FIG. 4 is a schematic diagram of a light-emitting diode packaged on a silicon substrate with a photoresist layer according to the present invention.

5 is a schematic diagram of exposure and development of part of the photoresist packaged on the silicon substrate of the light emitting diode of the present invention.

Fig. 6 is a structural view of the package of the light emitting diode of the present invention formed by etching grooves on the silicon substrate.

FIG. 7 is a structural diagram of a silicon substrate with a groove structure formed on the packaging silicon substrate of the light emitting diode of the present invention after removing the photoresist.

Fig. 8 is a cross-sectional view of digging or through-hole processing for the package of the light emitting diode of the present invention.

Fig. 9 is a structural diagram of a long insulating layer and a metallized layer in the package of the light emitting diode of the present invention.

FIG. 10A is a structural view of the packaging of the light emitting diode of the present invention by dividing the metal layer to form positive and negative electrode surfaces.

FIG. 10B is a schematic view of the positive and negative electrode surfaces of the packaging of the light emitting diode of the present invention by dividing the metal layer to form flip-chip bonding.

Fig. 11 is a structural diagram of LED crystal grain bonding, wire bonding, and glue dispensing for the packaged LED of the present invention.

FIG. 12 is a structural view of the packaging of the light-emitting diode of the present invention using LED chips to be bonded in a flip-chip manner and glue dispensed.

Fig. 13 is a structural diagram of the SMD type LED element packaged by dispensing and sealing glue and cutting of the light emitting diode of the present invention.

Fig. 14 is a structure diagram of an SMD-type LED element formed by flip-chip method of encapsulating LED grains of a light-emitting diode according to the present invention.

Fig. 15 is a configuration diagram of electrodes on the back of the packaged SMD type LED element of the light emitting diode of the present invention.

FIG. 16 is a perspective view of an SMD-type LED element packaged with flip-chip bonding of a light-emitting diode according to the present invention.

Fig. 17 shows the surface sealant of the packaged SMD type LED element of the light emitting diode of the present invention formed by molding.

Fig. 18 is a structure with a convex lens formed by sealing the surface of the packaged SMD LED element of the light emitting diode of the present invention.

FIG. 19 is a structural view of the encapsulation silicon substrate of the light-emitting diode of the present invention, which is etched into vertical wall grooves with a crystal orientation of 110. FIG.

Fig. 20 is a package structure view of a light-emitting diode package of the present invention in which multiple LED crystal grains can be placed in a single groove reflective seat on a wafer substrate at the same time.

Detailed ways

Figure 1 is a structural diagram of a traditional metal bracket SMD type LED (commonly known as TOPLED type). The manufacturing process is to first inject the metal bracket and heat-resistant plastic material (PPS) into a groove shape 2, and then solidify the crystal 3 and wire 4. Sealing 5 and other actions, the main packaging materials are plastic and epoxy resin (EPOXY).

Figure 2 is a structural diagram of a SMD-type LED on a traditional circuit board. The manufacturing process is to first fix the LED crystal grains on the substrate 6 and punch the electrode wire 4, then form the sealant 5 by molding, and then cut it into granular SMD. Type LED components, the main packaging material is transparent epoxy resin.

The encapsulation of light-emitting diode of the present invention please refer to as shown in Figure 3, at first on the silicon wafer substrate 8 one layer of photoresist layer 9 (as shown in Figure 4), utilize the exposure development mode to remove the photoresist of exposure development area 10 (as shown in Figure 4). 5), the silicon wafer is etched by etching solution (KOH) to form grooves. Since the silicon wafer 8 adopts the structure of 100 crystallographic orientation, the groove etched is an inclined wall 12 with an inclined angle of 54.74°. The inclined wall is beneficial to the reflection of light. FIG. 7 is a structural diagram of a silicon substrate with a groove structure formed after removing the photoresist. FIG. 8 is a photoresist on the back of the silicon substrate 8 and a photomask at the relative position on the back of the groove with a development electrode through-hole pattern, and use exposure, development and dry etching (RIE or ICP) to dig holes (semi-through holes) 13 , while making the electrode guide 14 (as shown in Figure 8), the main purpose of the half-through hole 13 is to cut the cutting line directly from the center of the half-through hole 13 when cutting the SMD component particles, so that the two ends of the SMD-type LED component are formed. Each of them has a semicircular structure as shown in Figure 10 (A) and Figure 16, because the inner wall of the semicircle will be coated with a metal layer to facilitate the soldering of the SMD type LED element at the soldering point with other circuit board circuits.

The electrode through hole 14 in the silicon substrate in FIG. 8 functions as a guiding electrode.

After the substrate structure of the silicon substrate has been completed, since the silicon substrate itself is a semiconductor, a good insulating film must be formed on its surface. At present, the insulating film can be silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ), an insulating layer on the surface can be formed as long as oxygen or nitrogen gas is passed through the high-temperature furnace, as shown in 15 of FIG. 9 , and a metal layer 16 must be plated after the insulating layer 15 is grown. Because the metal layer 16 must be plated to the front, back and through holes of the silicon wafer, it is best to finish it all at one time by electroplating, and also can form the back metal electrodes 18, 17; and the metal electrodes in the front groove are difficult Formed by exposure and development, it must be processed and cut by laser (Nd-YAG) to form the positive and negative electrode surfaces, as shown in Figure 10, the electrode surfaces 17A and 18A, the dividing line 19 is an insulating area; The die must be connected to the electrodes by bonding wires, and FIG. 10(B) is an electrode distribution diagram for a flip-chip (FlipChip) LED die. The substrate of gallium nitride blue light, green light and other LED grains is transparent aluminum oxide single crystal. If flip-chip packaging is used and the groove reflector of the present invention is used, the luminous brightness will be higher than that of the traditional packaging structure. more than double.

Fig. 11 is to put the LED crystal 3 on the electrode surface 18A in the groove of the silicon substrate, at the same time make the metal wire 4 to connect the electrode 17A and seal the resin 5, and finally cut the silicon substrate dividing line 20 to form a diagram 13 SMD type LED components. Figure 12 and Figure 14 show the structure of the LED flip-chip package. Directly heat and weld the contact 21 on the electrode surface of 17A and 18A on the reverse side of the LED die, then apply the sealing resin 5, and cut the SMD type LED, as shown in Figure 10 And Fig. 13 is the encapsulation that selects traditional LED die.

Fig. 15 is a configuration diagram of electrodes on the back of the packaged SMD LED of the light emitting diode of the present invention. The back electrodes 17, 18 must be connected to the through-hole electrodes 14 and the electrodes 17A, 18A in the groove. Since the structure designed in the present invention will form a larger back electrode surface in order to connect the through-hole electrodes 14, for SMD components It is possible to form positive and negative electrode short circuit phenomenon easily during welding operation, for avoiding 17,18 two electrode faces are too close, therefore must print one deck insulating layer (varnish) 22 as shown in Figure 15 on it again.

FIG. 16 is a perspective view of an SMD-type LED element packaged by flip-chip bonding of the light-emitting diode of the present invention. The packaging substrate 8 is all silicon substrates, not traditional epoxy resin.

Fig. 17 is a die-casting molding method for encapsulating the surface of the SMD type LED element of the light-emitting diode of the present invention. Only the front surface has the encapsulant 5, and the encapsulating substrate 8 is all silicon substrates. Prior to this, most of the sealing glue in the groove of the silicon substrate was dispensing. The advantage was that the process was simple and no mold was needed. As shown in Figure 18, the surface can be sealed with a molding method.

Illustrate by above embodiment that the present invention is that light-emitting diode grain (GaAs, GaN, SiC etc.) is directly fixed on the silicon wafer substrate that has groove, and silicon wafer substrate itself is exactly LED encapsulation base material, and traditional SMD type LED encapsulation material It is usually an epoxy resin product. Compared with the traditional method, the present invention has the advantages of easy miniaturization, good heat dissipation, strong luminous brightness, and heat resistance.

The embodiment described above is based on the crystal orientation of the single crystal silicon wafer 100. If a wafer with a crystal orientation of 110 is used instead, the wet-etched groove is a vertical wall groove as shown in FIG. 19, but this groove also It can be used on SMD LED components with small light emitting angle.

Figure 20 is a structure that can place multiple LED crystal grains on the same groove to obtain the effect that a single SMD LED component has high brightness.

In addition, if the present invention does not use a silicon crystal single wafer but instead uses other single wafers such as silicon dioxide single crystal commonly known as quartz single crystal (SiO ₂ ), the structure with grooves can also be obtained after etching, but the angle of the inclined wall is different from that of silicon. , different results must be obtained depending on which crystallographic orientation is used.

Claims (15)

1. the encapsulation of a light-emitting diode is characterized in that, the manufacture method of substrate is:

With the silicon wafer is substrate, the groove reflection seat that photoresist layer utilizes the wet etching mode to etch behind exposure imaging to have inclined wall on its front, in addition at the back side of silicon wafer substrate same on photoresist layer and relative position at the bottom portion of groove back side be provided with the electrode hole pattern and behind exposure imaging, utilize the dry ecthing mode to etch the perforation electrode hole, remove photoresistance, make the silicon substrate surface form the insulating barrier of one deck silica or silicon nitride through high temperature furnace oxidation or nitrogen treatment silicon wafer substrate, utilize plating mode to make silicon substrate just, all plate the layer of metal conductive layer in reverse side and the perforation electrode hole, and with laser processing the electrode surface in the groove is divided into and just has, the electrode contact surface of negative electrode is placed in one and and electrode engagement in order to the luminescent grain of light-emitting diode.

2. the encapsulation of a kind of light-emitting diode as claimed in claim 1 is characterized in that, wherein the plating conductive layer must have conduction and light reflection function simultaneously, and its material is silver, gold, palladium, platinum etc.

3. the encapsulation of a kind of light-emitting diode as claimed in claim 1 is characterized in that, wherein silicon wafer substrate selects for use the silicon wafer of 100 crystal orientations can etch the groove of inclined wall.

4. the encapsulation of a kind of light-emitting diode as claimed in claim 1 is characterized in that, wherein silicon wafer substrate selects for use the silicon wafer energy etching of 110 crystal orientations to provide the groove of vertical wall.

5. the encapsulation of a kind of light-emitting diode as claimed in claim 1 is characterized in that, wherein wet etch solution is alkalescence when (potassium hydroxide), and its photoresistance must be with acid development photoresistance.

6. the encapsulation of a light-emitting diode, it is characterized in that, silicon wafer substrate makes silicon wafer surface form one deck silicon nitride layer through the heating of nitrogen high temperature furnace, go up photoresistance again and cooperate the light shield exposure imaging, with reactive ion etching the silicon nitride layer in the district of developing is removed, after etch structure with wet etch method again with groove; Photoresistance and cooperate light shield to be provided with the electrode hole pattern to do exposure imaging on the back side of silicon wafer substrate at the relative position of groove, with reactive ion etching silicon nitride layer is removed again, produce the perforation electrode hole with dry ecthing induction coupled plasma, make groove and perforation electrode hole inwall form a layer insulating through oxidation or nitrogen treatment silicon wafer substrate, again with the silicon substrate metal cladding, utilize laser processing to be partitioned into the interior positive and negative electrode face of groove, place in the groove and and electrode engagement in order to LED crystal particle.

7. the encapsulation of light-emitting diode as claimed in claim 6 is characterized in that, but wherein silicon wafer substrate selects for use 100 crystal orientation etchings to provide the groove structure of inclined wall.

8. the manufacture method of the base plate for packaging of light-emitting diode as claimed in claim 6 is characterized in that, wherein silicon wafer substrate selects for use the etching of 110 crystal orientations energy to provide the groove structure of vertical wall.

9. the encapsulation of a light-emitting diode, it is characterized in that, lumination of light emitting diode crystal grain is positioned in the silicon wafer substrate groove with groove reflection seat, and the positive and negative electrode of lumination of light emitting diode crystal grain is connected the positive and negative electrode of silicon wafer substrate groove, utilize sealing resin-coating lumination of light emitting diode crystal grain and fill up whole groove, make behind the sealing resin solidification through heating and cut into granular surface-mounted light-emitting diode.

10. the encapsulation of light-emitting diode as claimed in claim 9 is characterized in that, wherein the sealing resin is a kind of silica gel or epoxy resin of transparent high temperature resistant.

11. the encapsulation of a light-emitting diode, by wafer substrate, lumination of light emitting diode crystal grain, potting resin etc. are formed, wherein:

Lumination of light emitting diode crystal grain: luminescent grain with positive and negative electrode face;

Wafer substrate: have the groove reflection seat, place lumination of light emitting diode crystal grain, and have the positive and negative electrode face that connects lumination of light emitting diode crystal grain;

Sealing resin: coat lumination of light emitting diode crystal grain and fill up the whole groove of wafer substrate;

Its characteristic person is: lumination of light emitting diode crystal grain is placed in the wafer substrate groove with groove reflection seat, and connect its positive and negative electrode, make the sealing resin fill up whole groove with a glue or mold casting forming mode again, cut into the binding type light-emitting diode again.

12. the encapsulation of light-emitting diode as claimed in claim 11 is characterized in that, wherein wafer substrate can be silicon wafer or silica wafers substrate.

13. the sealing as claim 11 or 12 described light-emitting diodes is characterized in that, wafer substrate selects for use its different crystalline lattice orientation then can etch the groove of different inclination angle.

14. the encapsulation of light-emitting diode as claimed in claim 11 is characterized in that, wherein the sealing resin makes its surface form the structure with convex lens function with the moulding of die casting mode.

15. the encapsulation of light-emitting diode as claimed in claim 11 is characterized in that, wherein can place two above LED crystal particle simultaneously in the single groove reflection seat of wafer substrate.

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