Flip-chip type black light sensor package structure

Abstract

This invention discloses a flip-chip black light sensor packaging structure, including a light emitting chip, a light receiving chip, a wafer, a black molding compound, a reflective layer for the emitting region, and a reflective layer for the receiving region. The light emitting chip and the light receiving chip are inverted and arranged above the wafer and electrically connected to the wafer, and are packaged on the wafer by the black molding compound. A emitting cavity is formed between the light emitting chip and the wafer, and a receiving cavity is formed between the light receiving chip and the wafer. An emitting slot structure is formed on the light emitting chip and the black molding compound. The reflective layer for the emitting region is disposed within the emitting cavity, and light is reflected by the reflective layer for the emitting region and then emitted through the emitting slot structure. A receiving slot structure is formed on the light receiving chip and the black molding compound. The reflective layer for the receiving region is disposed within the receiving cavity, and light enters the receiving cavity through the receiving slot structure and is reflected by the reflective layer for the receiving region to the light receiving chip. This invention relates to the field of semiconductor packaging technology and can solve the problems existing in the prior art.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging technology, and in particular to a flip-chip black light sensor packaging structure. Background Technology

[0002] Please see the appendix Figure 1 The existing optical sensor includes a substrate 1 and a light emitting chip 2 and a light receiving chip 3 electrically connected to the substrate 1. The light emitting chip 2 and the light receiving chip 3 are encapsulated on the substrate 1 by a cover or a transparent plastic sealant 4. The light receiving end of the light receiving chip 3 is wrapped by an epoxy resin dispensing process.

[0003] Existing optical sensors suffer from the following technical problems:

[0004] 1. Since the cover or transparent plastic sealant cannot completely block light, there is an interference problem between emitted and incident light, which affects the sensitivity of the light sensor.

[0005] 2. The cap or transparent plastic sealant is easily affected by temperature during the encapsulation process, resulting in a high shrinkage rate and causing the package to warp, which affects the product quality of the optical sensor.

[0006] 3. The light emitting chip and the light receiving chip are electrically connected to the substrate by wire bonding, resulting in a relatively large thickness after packaging.

[0007] 4. The epoxy resin dispensing process is difficult and prone to glue overflow.

[0008] 5. The lid has a quality problem with burrs (burr size approximately 30-100um) during the cutting process.

[0009] Therefore, there is a need to provide a flip-chip black light sensor packaging structure that can solve the above-mentioned technical problems. Summary of the Invention

[0010] The purpose of this invention is to provide a flip-chip black light sensor packaging structure that can solve the above-mentioned technical problems.

[0011] This invention is implemented as follows:

[0012] A flip-chip black light sensor package structure includes a light emitting chip, a light receiving chip, a wafer, a black molding compound, a reflective layer for the emitting region, and a reflective layer for the receiving region. The light emitting chip and the light receiving chip are inverted and arranged above the wafer and electrically connected to the wafer. The light emitting chip and the light receiving chip are packaged on the wafer by the black molding compound, and a emitting cavity is formed between the bottom of the light emitting chip and the wafer, and a receiving cavity is formed between the bottom of the light receiving chip and the wafer. A emitting slot structure for light to be emitted is formed on the light emitting chip and the black molding compound. The reflective layer for the emitting region is disposed on the wafer within the emitting cavity, so that the light from the light emitting chip is reflected by the reflective layer for the emitting region and then emitted through the emitting slot structure. A receiving slot structure for light to be received is formed on the light receiving chip and the black molding compound. The reflective layer for the receiving region is disposed on the wafer within the receiving cavity, so that the light enters the receiving cavity through the receiving slot structure and is reflected by the reflective layer for the receiving region to the light receiving chip.

[0013] The aforementioned emission slot structure includes a first emission slot formed on the optical emission chip and a second emission slot formed on the black plastic encapsulation. The bottom of the first emission slot is connected to the emission cavity, the top of the first emission slot is connected to the bottom of the second emission slot, and the top of the second emission slot extends upward through the black plastic encapsulation.

[0014] One or more emitting ends on the light emitting chip are located inside the emitting cavity and facing the emitting region reflective layer, and the light reflected by the emitting region reflective layer passes through the first emitting slot and the second emitting slot.

[0015] The receiving slot structure includes a first receiving slot formed on the optical receiving chip and a second receiving slot formed on the black plastic encapsulation. The bottom of the first receiving slot is connected to the receiving cavity, the top of the first receiving slot is connected to the bottom of the second receiving slot, and the top of the second receiving slot extends upward through the black plastic encapsulation.

[0016] One or more receiving ends on the optical receiving chip are located inside the receiving cavity and facing the receiving area reflective layer. Light rays that pass through the first receiving slot and the second receiving slot and enter the receiving cavity irradiate the receiving area reflective layer and are reflected by the receiving area reflective layer to one or more receiving ends.

[0017] The edge of the light-emitting chip is electrically connected to the wafer through a solder ball, so that the light-emitting chip forms an emission cavity between the solder ball and the wafer.

[0018] The edge of the optical receiving chip is electrically connected to the wafer via solder balls, so that the optical receiving chip forms a receiving cavity between the solder balls and the wafer.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. By inverting and mounting the light emitting chip and the light receiving chip on the wafer and electrically connecting them to the wafer through solder balls, the present invention can form an emitting cavity between the light emitting chip and the wafer, and a receiving cavity between the light receiving chip and the wafer. At the same time, slots are made at the corresponding positions of the light emitting chip, the light receiving chip and the black plastic package to form an emitting slot structure for light to be emitted and a receiving slot structure for light to be received, which ensures the light receiving and emitting functions of the light sensor and can reduce the package size by more than 30%.

[0021] 2. Because the present invention uses a wafer, the substrate is thinner than that of the prior art, which can reduce the packaging thickness and thus further reduce the packaging size.

[0022] 3. Because this invention uses a black plastic encapsulation, it can form a 100% natural light-shielding barrier between the light emitting chip and the light receiving chip, avoiding the problem of interference between emitted and incident light, effectively improving the sensitivity of the light sensor, and is not affected by temperature. It also avoids warping of the package caused by high shrinkage rate, ensuring the product quality of the light sensor. At the same time, there is no need for epoxy resin dispensing process, reducing the process difficulty and avoiding the problem of glue overflow during dispensing. There is also no need to install a cap, avoiding the quality problem of burrs from cap cutting. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the packaging structure of an existing optical sensor;

[0024] Figure 2 This is a schematic diagram of the flip-chip black light sensor packaging structure of the present invention;

[0025] Figure 3 This is a schematic diagram of the first emitting slot on the light emitting chip in the flip-chip black light sensor packaging structure of the present invention;

[0026] Figure 4 This is a schematic diagram of the first receiving slot on the light receiving chip in the flip-chip black light sensor packaging structure of the present invention.

[0027] In the figure, 1 is the substrate, 2 is the light emitting chip, 201 is the first emitting slot, 202 is the emitting end, 3 is the light receiving chip, 301 is the first receiving slot, 302 is the receiving end, 4 is the transparent molding compound, 5 is the wafer, 6 is the black molding compound, 601 is the second emitting slot, 602 is the second receiving slot, 7 is the reflective layer of the emitting area, 8 is the reflective layer of the receiving area, 9 is the solder ball, 10 is the emitting cavity, and 11 is the receiving cavity. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0029] Please see the appendix Figure 2A flip-chip black light sensor packaging structure includes a light emitting chip 2, a light receiving chip 3, a wafer 5, a black molding compound 6, a reflective layer for the emitting region 7, and a reflective layer for the receiving region 8. The light emitting chip 2 and the light receiving chip 3 are inverted and arranged above the wafer 5 and electrically connected to the wafer 5. The light emitting chip 2 and the light receiving chip 3 are packaged on the wafer 5 by the black molding compound 6, and a emitting cavity 10 is formed between the bottom of the light emitting chip 2 and the wafer 5, and a receiving cavity 11 is formed between the bottom of the light receiving chip 3 and the wafer 5. The light emitting chip 2 and the black plastic encapsulation 6 have emitting slotted structures for light to be emitted. The emitting region reflective layer 7 is disposed on the wafer 5 inside the emitting cavity 10, so that the light from the light emitting chip 2 is reflected by the emitting region reflective layer 7 and then emitted through the emitting slotted structure. The light receiving chip 3 and the black plastic encapsulation 6 have receiving slotted structures for light to be received. The receiving region reflective layer 8 is disposed on the wafer 5 inside the receiving cavity 11, so that the light is received through the receiving slotted structure into the receiving cavity 11 and reflected by the receiving region reflective layer 8 to the light receiving chip 3.

[0030] This invention uses wafer level packaging (WLP), which is thinner than the substrate of existing technologies, thus reducing the thickness of the packaging structure.

[0031] The light emitting chip 2 and the light receiving chip 3 are packaged on the wafer 5 using a black molding compound 6. The black molding compound 6 is made of opaque black molding compound, forming a 100% natural light-shielding barrier between the light emitting chip 2 and the light receiving chip 3, avoiding interference between emitted and incident light and ensuring the sensitivity of the light sensor. Furthermore, the black molding compound 6 is less susceptible to temperature changes, avoiding warping issues caused by high shrinkage rates and ensuring the product quality of the light sensor. Simultaneously, the black molding compound 6 can replace the cap in existing technologies, avoiding the burr quality issues caused by cap cutting, eliminating the need for the existing epoxy resin dispensing process, reducing packaging costs, and avoiding the problem of epoxy resin overflow during dispensing.

[0032] In existing optical sensor packaging structures, the light emitting chip 2 and the light receiving chip 3 are mounted face-up, meaning the light emitting chip 2 emits light upwards and the light receiving chip 3 receives light from top to bottom. In this invention, however, the light emitting chip 2 and the light receiving chip 3 are mounted upside down, meaning the light emitting chip 2 emits light downwards and the light receiving chip 3 receives light from bottom to top. Compared to wire bonding in existing technologies, this upside-down mounting of the light emitting chip 2 and the light receiving chip 3 can reduce the package size by more than 30%.

[0033] Because the light emitting chip 2 and the light receiving chip 3 are installed in reverse, their light emission direction is opposite to that of the prior art. An emission cavity 10 is formed between the light emitting chip 2 and the wafer, and the light emitted by the light emitting chip 2 at an angle downward is emitted by the emission area reflective layer 7. A receiving cavity 11 is formed between the light receiving chip 3 and the wafer, and the light entering the receiving cavity 11 is reflected at an angle upward to the light receiving chip 3 by the receiving area reflective layer 8, thus ensuring the light emission and reception function of the light sensor.

[0034] Please see the appendix Figure 2 and attached Figure 3 The aforementioned emitting slot structure includes a first emitting slot 201 formed on the light emitting chip 2 and a second emitting slot 601 formed on the black encapsulation body 6. The bottom of the first emitting slot 201 is connected to the emitting cavity 10, the top of the first emitting slot 201 is connected to the bottom of the second emitting slot 601, and the top of the second emitting slot 601 extends upward through the black encapsulation body 6.

[0035] The position and size of the first emission slot 201 on the light emission chip 2 and the position and size of the second emission slot 601 on the black plastic package 6 are adaptively slotted according to the emission position and angle of the light in the emission cavity 10 to ensure the light emission function of the light sensor.

[0036] One or more emitting ends 202 on the light emitting chip 2 are located inside the emitting cavity 10 and are positioned facing the emitting area reflective layer 7, and the light reflected by the emitting area reflective layer 7 passes through the first emitting slot 201 and the second emitting slot 601.

[0037] Preferably, the emitting region reflective layer 7, the first emitting slot 201, and the second emitting slot 601 can be arranged on the same straight line. Each emitting end 202 on the light emitting chip 2 can be located above and around the emitting region reflective layer 7. The inverted light emitting chip 2 concentrates light obliquely downwards onto the emitting region reflective layer 7 through each emitting end 202, and then the emitting region reflective layer 7 reflects the light outwards from the first emitting slot 201 and the second emitting slot 601, as shown in the attached diagram. Figure 2 The direction of the arrow on the left is indicated.

[0038] Please see the appendix Figure 2 and attached Figure 4 The receiving slot structure includes a first receiving slot 301 formed on the optical receiving chip 3 and a second receiving slot 602 formed on the black plastic encapsulation body 6. The bottom of the first receiving slot 301 is connected to the receiving cavity 11, the top of the first receiving slot 301 is connected to the bottom of the second receiving slot 602, and the top of the second receiving slot 602 extends upward through the black plastic encapsulation body 6.

[0039] The position and size of the first receiving slot 301 on the light emitting chip 2 and the position and size of the second receiving slot 602 on the black plastic encapsulation 6 are adaptively slotted according to the position and angle of the light entering the receiving cavity 11, so as to ensure the light receiving function of the light sensor.

[0040] One or more receiving ends 302 on the optical receiving chip 3 are located in the receiving cavity 11 and face the receiving area reflective layer 8. Light rays that pass through the first receiving slot 301 and the second receiving slot 602 and enter the receiving cavity 11 irradiate the receiving area reflective layer 8 and are reflected by the receiving area reflective layer 8 to one or more receiving ends 302.

[0041] Preferably, the receiving area reflective layer 8, the first receiving slot 301, and the second receiving slot 602 can be arranged on the same straight line. Each receiving end 302 on the optical receiving chip 3 can be located above and around the receiving area reflective layer 8. Light passing through the first receiving slot 301 and the second receiving slot 602 and entering the receiving cavity 11 is concentrated on the receiving area reflective layer 8 and reflected obliquely upwards by the receiving area reflective layer 8 to each receiving end 302 of the inverted optical receiving chip 3, as shown in the attached diagram. Figure 2 The direction of the arrow on the right side of the middle is shown.

[0042] The edge of the light emitting chip 2 is electrically connected to the wafer 5 through a solder ball 9, so that the light emitting chip 2 forms an emission cavity 10 between the solder ball 9 and the wafer 5.

[0043] Since the solder ball 9 has a certain height, an emission cavity (10) can be formed between the light emitting chip 2 and the wafer 5. The solder ball 9 has good conductivity and can electrically connect the light emitting chip 2 and the wafer 5 without wire bonding. This can further reduce the package size and ensure the reflection and emission of light in the emission cavity 10.

[0044] The edge of the optical receiving chip 3 is electrically connected to the wafer 5 through solder balls 9, so that the optical receiving chip 3 forms a receiving cavity 11 between the solder balls 9 and the wafer 5.

[0045] Because the solder ball 9 has a certain height, a receiving cavity 11 can be formed between the light receiving chip 3 and the wafer 5. The solder ball 9 has good conductivity and can electrically connect the light receiving chip 3 and the wafer 5 without wire bonding. This can further reduce the package size and ensure the reflection and reception of light in the receiving cavity 11.

[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the invention. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A flip-chip black light sensor packaging structure, characterized in that: The device includes a light emitting chip (2), a light receiving chip (3), a wafer (5), a black plastic encapsulation (6), a reflective layer for the emitting region (7), and a reflective layer for the receiving region (8). The light emitting chip (2) and the light receiving chip (3) are arranged upside down on the wafer (5) and electrically connected to the wafer (5). The light emitting chip (2) and the light receiving chip (3) are encapsulated on the wafer (5) by the black plastic encapsulation (6), and a emitting cavity (10) is formed between the bottom of the light emitting chip (2) and the wafer (5), and a receiving cavity (11) is formed between the bottom of the light receiving chip (3) and the wafer (5). The light emitting chip (2) and the black plastic encapsulation (6) have an emission slot structure for light to be emitted. The emission area reflective layer (7) is disposed on the wafer (5) inside the emission cavity (10), so that the light from the light emitting chip (2) is reflected by the emission area reflective layer (7) and emitted through the emission slot structure. The light receiving chip (3) and the black plastic encapsulation (6) have a receiving slot structure for light to be emitted. The receiving area reflective layer (8) is disposed on the wafer (5) inside the receiving cavity (11), so that the light is emitted into the receiving cavity (11) through the receiving slot structure and reflected by the receiving area reflective layer (8) to the light receiving chip (3). One or more emitting ends (202) on the light emitting chip (2) are located inside the emitting cavity (10) and facing the emitting region reflective layer (7); One or more receivers (302) on the optical receiver chip (3) are located inside the receiver cavity (11) and are positioned facing the receiver area reflective layer (8).

2. The flip-chip black light sensor packaging structure according to claim 1, characterized in that: The emission slot structure includes a first emission slot (201) formed on the light emission chip (2) and a second emission slot (601) formed on the black plastic encapsulation body (6). The bottom of the first emission slot (201) is connected to the emission cavity (10), the top of the first emission slot (201) is connected to the bottom of the second emission slot (601), and the top of the second emission slot (601) extends upward through the black plastic encapsulation body (6).

3. The flip-chip black light sensor packaging structure according to claim 2, characterized in that: The light reflected by the reflective layer (7) of the emission area passes through the first emission slot (201) and the second emission slot (601).

4. The flip-chip black light sensor packaging structure according to claim 1, characterized in that: The receiving slot structure includes a first receiving slot (301) formed on the optical receiving chip (3) and a second receiving slot (602) formed on the black plastic encapsulation body (6). The bottom of the first receiving slot (301) is connected to the receiving cavity (11), the top of the first receiving slot (301) is connected to the bottom of the second receiving slot (602), and the top of the second receiving slot (602) extends upward through the black plastic encapsulation body (6).

5. The flip-chip black light sensor packaging structure according to claim 4, characterized in that: Light rays passing through the first receiving slot (301) and the second receiving slot (602) and entering the receiving cavity (11) irradiate the receiving area reflective layer (8) and are reflected by the receiving area reflective layer (8) to one or more receiving ends (302).

6. The flip-chip black light sensor packaging structure according to any one of claims 1-3, characterized in that: The edge of the light emitting chip (2) is electrically connected to the wafer (5) through a solder ball (9), so that the light emitting chip (2) forms an emission cavity (10) between the solder ball (9) and the wafer (5).

7. The flip-chip black light sensor packaging structure according to claim 1, 4, or 5, characterized in that: The edge of the optical receiving chip (3) is electrically connected to the wafer (5) through a solder ball (9), so that the optical receiving chip (3) forms a receiving cavity (11) between the solder ball (9) and the wafer (5).

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