JP4159147B2 - Semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device in which a light-emitting element and a light-receiving element are individually sealed with resin, and particularly relates to a reduction in the thickness of the device.
[0002]
[Prior art]
Recently, multimedia devices such as sub-notebook computers, personal digital assistants, and electronic still cameras have made remarkable progress. Since these devices require portability, they are required to be easy to send and receive data to and from the outside, and have a device that connects the external device and the main body cordlessly using an optical signal such as infrared rays. There are many. Among them, the IrDA (Infrared Data Association) standard that uses infrared light having a wavelength of 870 nm as an optical signal is most popular.
[0003]
In order to use data communication based on the IrDA standard, it is necessary that both devices to be connected include a light emitting element that emits an infrared signal and a light receiving element that receives the infrared signal. The light emitting element and the light receiving element may be incorporated in the electronic device as separate packages, respectively, or may be supplied as a module housed in one package.
[0004]
FIG. 3 shows an example of a semiconductor device for infrared data communication in which a light emitting element and a light receiving element are housed in one package (for example, Japanese Patent Laid-Open No. 10-70304). In this apparatus, a light receiving element 2 and a light emitting element 3 provided in the form of a semiconductor chip are housed in the apparatus main body 1, and are molded with a resin that is transparent to at least infrared rays. In particular, in the light receiving element 2, a light receiving photodiode PD and a peripheral circuit such as an amplifier circuit may be integrated in the same chip.
[0005]
The photodiode PD of the light receiving element 2 provided in the semiconductor chip has a structure for receiving light in a direction perpendicular to the surface of the semiconductor chip. Therefore, both the light receiving element 2 and the light emitting element 3 are configured to emit / receive the optical signal 6 perpendicular to the semiconductor chip. A hemisphere is formed above each element for condensing the optical signal 6. The lenses 4 and 5 are made of resin.
[0006]
[Problems to be solved by the invention]
In order to meet the demand for reduction in size and size in electronic devices, it is indispensable to limit the height of the electronic component itself that is fixed on the printed circuit board. However, if the apparatus main body 1 of FIG. 3 is mounted so that the optical signal 6 is introduced in a direction perpendicular to the printed circuit board, the apparatus main body 1 is high due to the presence of the lenses 4 and 5 and the like, and the overall thickness is reduced. There were drawbacks that were difficult.
[0007]
On the other hand, as shown in FIG. 4, it is possible to introduce the optical signal 6 in the horizontal direction with respect to the printed circuit board 7 by bending the lead and placing the lenses 4 and 5 sideways. However, since the semiconductor chips of the light receiving element 2 and the light emitting element 3 are mounted so as to stand vertically, it is impossible in principle to make the height during mounting below the size of the semiconductor chip. There was a drawback that it was difficult to form.
[0008]
[Means for Solving the Problems]
The present invention has been made in view of the above-mentioned problems, and a semiconductor chip is fixed on an island, an electrode pad of the semiconductor chip and a lead terminal are connected by wire, and the semiconductor chip including a part of the lead terminal is made of resin. A semiconductor device that seals and leads the lead terminal to the outside from a side surface of the sealing body,
A groove having a predetermined depth in the sealing body above the semiconductor chip;
The lead terminal is led out from a side surface of the sealing body at a first height with respect to the position of the island;
A lead terminal extending to the inside of the sealing body has a portion extending at a second height located between the position of the island and the first height;
The wire is connected to a portion extending at the second height.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, the light receiving element 2 and the light emitting element 3 are housed in one package. FIG. 1A is a plan view showing the structure of the present invention, and FIG. 2A is a cross-sectional view taken along line AA in FIG. FIG. 2 and FIG. 2B are cross-sectional views taken along line BB in FIG.
[0010]
In these drawings, reference numeral 21 denotes an island on which the light receiving element 2 is mounted, 22 denotes an island on which the light emitting element 3 is mounted, and 23 denotes a lead terminal for external connection. These are provided by a lead frame made of an iron or copper-based material, and the light receiving element 2 and the light emitting element 3 are fixed to the surface of each island 21 and 22 with an adhesive such as solder.
[0011]
The light receiving element 2 is a PIN photodiode provided as a semiconductor chip, and may be one in which peripheral drive circuits and the like are integrated on the same chip. A reference symbol PD in the drawing indicates a photodiode portion (light receiving surface) of the light receiving element 2. Electrode pads 30 are formed on the surface of the semiconductor chip, and the electrode pads and leads 23 are connected by bonding wires 24.
[0012]
The light emitting element 3 is an LED chip that is provided as a semiconductor chip and emits infrared light having a wavelength of, for example, 870 nm. An LED is an element that emits light from the entire chip and emits light in all directions. For this reason, the island 22 to which the chip is fixed is processed into a shape like a conical “bowl”, and the optical signal 6 from the light emitting element 3 fixed to the center of the island 22 is reflected by the inclined side wall 22 a of the island 22. The light is collected in one direction. The island 22 becomes one terminal of an anode or a cathode, and the electrode pad 30 formed on the chip surface becomes the other terminal. The electrode pad 30 serving as the other terminal is connected to a predetermined lead terminal 23 by a bonding wire 24.
[0013]
The light emitting element 2 and the light receiving element 3 fixed to the islands 21 and 22 are transfer-molded with a resin transparent to at least infrared light including the tip of the lead 23. The resin constitutes the sealing body 25, and the back surfaces of the islands 21 and 22 are exposed on one surface of the sealing body 25 in the same plane as the surface of the sealing body 25.
[0014]
The lead terminal 23 is led to the outside at a first height (FIG. 2 (A): t1) with respect to the islands 21 and 22 from near the middle of one side surface 25a of the sealing body 25, and is suitable for surface mounting applications. Thus, it is bent into a Z shape. The lead terminal 23 extending inside the sealing body 25 extends to the vicinity of the islands 21 and 22 while maintaining the first height t1. A part of the lead terminal 23 is an island lead 23a, 23b continuous to the islands 21, 22, and these are subjected to a bending process for making a difference between the islands 21, 22 and the first height t1. The portion subjected to the bending process is sealed inside the sealing body 25.
[0015]
Further, some of the leads 23c are bent inside the sealing body 25, and the second height t2 located between the first height t1 and the islands 21 and 22 is provided. It is extended with.
[0016]
On the upper part of the photodiode portion PD of the light receiving element 2, a resin 26 of the sealing body 25 is recessed to a predetermined depth to form a recess 26, and a reflecting surface 27 is configured by the side wall of the recess 26. The reflective surface 27 is formed by forming a male part corresponding to the recess 26 in the mold when the sealing body 25 is transfer molded, or the surface of the sealing body 25 is shaved after completion. Is formed. The reflection surface 27 plays a role of reflecting the optical signal 6 introduced from the other side surface 25 b of the sealing body 25 to reach the photodiode portion PD of the light receiving element 2.
[0017]
The reflecting surface 27 becomes a reflecting surface due to the difference in the refractive index of the material at the boundary. Therefore, the entire sealing body 25 is processed with a matte finish, whereas the reflecting surface 27 has a mirror finish with a smaller surface roughness. Further, the surface of the reflecting surface 27 may be covered with a light-shielding metal film or the like in order to improve the reflectance.
[0018]
On the other hand, similarly to the light receiving element 2, a concave portion 26 and a reflecting surface 27 are formed on the light emitting element 3 side. The signal light 6 emitted from the light emitting element 3 is reflected by the reflection surface 27 and has a function of emitting the light from the other side wall 25b of the sealing body 25 to the outside.
[0019]
In this way, by allowing the optical signal 6 to enter and exit from the other side surface 25b of the sealing body 25 through the reflecting surface 27 formed by the concave portion 26, the overall height of the sealing body 25 can be kept low. A lens body that collects the optical signal 6 may be integrally molded with resin on the other side surface 25b.
[0020]
In the above-described semiconductor device, it is apparent that there are some restrictions because the light is reflected by the reflecting surface 27. One of the constraints is the position and depth of the recess 26. This is because it is necessary for the reflecting surface 27 to cover the entire surface of the photodiode part PD or the light emitting element 3 in plan view (observed as shown in FIG. 1) while maintaining a designed reflection angle. Naturally, the deepest portion 26 a of the recess 26 needs to be shifted to the side surface 25 a side from the photodiode PD or the light emitting element 3. Another limitation is the arrangement of the lead terminals 23. Since the optical signal 6 is incident / exited from the other side surface 25 b side of the sealing body 25, the lead terminals 23 for electrical connection of each semiconductor chip are concentrated on the one side surface 25 a side of the sealing body 25. It is easy to arrange. If the electrode pad 30 of the semiconductor chip is also arranged on the side surface 25a side, the loop length of the wire 24 can be shortened, which is convenient.
[0021]
Under such restrictions, when it is attempted to connect the electrode pad 30 and the lead terminal 23 with the bonding wire 24, the loop of the wire 24a may interfere with the deepest portion of the recess 26 as is apparent from FIG. . In particular, on the light emitting element 3 side, since the chip size of the semiconductor chip is relatively small and the electrode pad is often arranged near the center thereof, the electrode pad 30 is often located near the deepest portion of the recess 26. The interference is likely to occur. Further, when the electrode pad 30 is arranged near the deepest part of the recess 26 on the light receiving element 2 side, the same interference may occur.
[0022]
In the present invention, the portion 31 extending at the second height t2 is formed at the tip portion of the lead terminal 23, and the wire 24 is connected to the portion extending at the second height t2, so that the wire loop The interference between the wire 24 and the recess 26 is avoided by suppressing the height. The other non-interfering electrode pad 30 is connected to the lead terminal 23 having the first height t1 as shown in FIG. Of course, all the lead terminals 23 may be bent to have the second height t2.
[0023]
As described above, the semiconductor device of the present invention bends the transmission path of the optical signal 6 so that the optical signal 6 enters and exits from the side surface 25b of the sealing body 25 when the device is surface-mounted on a printed board. Thus, the height of the entire printed circuit board can be kept low, and the electronic equipment can be made thinner. At that time, the bending of the tip of the lead terminal 23 is bent to avoid interference between the recess 26 and the wire 24, thereby preventing the height of the entire semiconductor device from increasing.
[0024]
In addition, as an optical semiconductor device, in addition to the structure in which both the light receiving element 2 and the light emitting element 3 are sealed, a device in which either one is sealed may be used.
[0025]
【The invention's effect】
As described above, according to the present invention, by providing the reflecting surface 27 with the recess 26, there is an advantage that an optical semiconductor device capable of entering and exiting the optical signal 6 from the side surface 25b of the resin can be realized. Since this apparatus can reduce the overall height of the sealing body 25, it can realize a significant reduction in thickness when mounted on a printed circuit board.
[0026]
Furthermore, by providing a portion 31 extending at the second height t2 at the tip of the lead terminal 23c, the height of the wire loop can be suppressed, and interference between the bonding wire 24 and the deepest portion of the recess 26 can be avoided. Have advantages. In addition, there is an advantage that the height of the entire apparatus can be reduced by preventing interference.
[Brief description of the drawings]
FIG. 1 is a plan view for explaining a first embodiment;
FIG. 2 is a cross-sectional view illustrating a first embodiment.
FIG. 3 is a perspective view illustrating a conventional example.
FIG. 4 is a perspective view illustrating a conventional example.

Claims (1)

A semiconductor chip for light emission or reception is fixed on the island, electrode pads of the semiconductor chip and lead terminals are connected by wire, the semiconductor chip including a part of the lead terminals is resin-sealed, and the sealing is performed. A semiconductor device in which the lead terminal is led out from the side of the body,
The sealing body above the semiconductor chip has a concave portion with a predetermined depth having an optical reflecting surface, and reflects an optical signal from the reflecting surface and from the side surface of the sealing body, or the sealing It transmits optical signals to the side of the body,
The lead terminal is led out from a side surface of the sealing body at a first height with respect to the position of the island;
A lead terminal extending to the inside of the sealing body has a portion extending at a second height located between the position of the island and the first height;
The semiconductor device, wherein the wire is connected to a portion extending at the second height.

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