JP3554640B2 - Package for mounting semiconductor chip, semiconductor device and method of manufacturing the same - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention is effective when applied to a semiconductor package structure technology which can be manufactured at a low cost because it is excellent in the mounting property to a semiconductor device, especially in a circuit board and the reliability of electrical conduction with the circuit board, and has excellent handling characteristics.
[0002]
[Prior art]
As a mounting technique of a semiconductor device having lead pins, a semiconductor device having a package structure called DIP (Dual Inline Package) or SIP (Single Inline Package) is used, and the tip of a lead pin protruding from a package is provided on a circuit board. (Insertion mounting method) is known in which the lead pin is soldered to an electrode surrounding the insertion hole and inserted into the insertion hole.
[0003]
In this insertion mounting method, there is a problem that work for forming an insertion hole in the circuit board is required, and bending accuracy of the lead pin is required for the position of the insertion hole, and handling during mounting is difficult. .
[0004]
There is also known a type in which the tip of a lead pin is bent in the same direction as the surface of the circuit board to perform surface mounting. The structure of the surface mount type resin package will be described with reference to FIGS.
[0005]
A lead frame 1 processed into a predetermined shape is prepared. The lead frame 1 has an island portion 2 for mounting a semiconductor chip in the center, and has an inner lead 3 extending to the vicinity of the island portion and an outer lead 4 for supporting the inner lead 3. I have. In the state shown in the figure, these parts are all processed integrally.
[0006]
Next, as shown in FIG. 2, the semiconductor chip 5 is bonded to the upper surface of the island portion 2 by ultrasonic vibration or thermocompression. Then, the electrodes provided on the upper surface of the semiconductor chip 5 and the inner leads 3 are electrically connected by a conductive thin wire (wire 6) made of gold, aluminum, or the like.
[0007]
Next, as shown in FIG. 3, the semiconductor chip 5, the wires 6, and the inner leads 3 are sealed with a resin. This is performed by positioning the lead frame in a mold having a cavity and injecting a thermosetting resin or a thermoplastic resin into the mold.
[0008]
Finally, as shown in FIG. 4, the outer lead 4 protruding from the resin body 7 is bent. That is, first, the outer lead 4 protruding from the resin body 7 is bent in an L-shape toward the outer bottom surface of the resin body 7 in FIG. Next, the outer lead is bent outward from the resin body 7 at the tip of the outer lead. As a result, the tip of the outer lead (portion indicated by "C" in the figure) becomes flat, and it becomes possible to join the electrode on the circuit board by soldering.
[0009]
[Problems to be solved by the invention]
Since the semiconductor device having such a surface mounting structure does not require processing such as preparing an insertion hole on the circuit board side, the mounting efficiency is improved as compared with the plug-in mounting method, but the outer surface is formed from the uppermost surface of the resin body. Accuracy of the distance to the lead tip (C) (distance indicated by “A” in the figure), accuracy of the distance from the inner lead (3) to the outer lead tip (C) (distance indicated by “A ′” in the figure), In addition, high processing accuracy was required to prevent an error from occurring in the distance from the center position of the island portion 2 to the tip (C) of the outer lead (the distance indicated by “B” in the figure).
[0010]
In other words, if the processing accuracy is not ensured, a deviation between the electrode position of the circuit board and the joint position (C) of the outer lead occurs at the time of mounting, which may hinder power supply to the semiconductor device or read / write of a signal. there were.
Furthermore, the distance (D) from the tip of the inner lead 3 to the island portion 2 has no flexibility and the package design is restricted.
[0011]
Further, if even a small amount of the lead floats among the many outer leads, there is a possibility that a defective connection with the electrode of the circuit board may occur.
Further, as shown in FIG. 4, since the lead is bent at least twice after the formation of the resin main body, stress is applied to the resin main body (the position shown by "d" in FIG. 4) at the time of bending. Cracks were likely to occur, resulting in poor appearance and reduced moisture resistance.
[0012]
In addition, due to the structure in which the outer leads protrude greatly from the resin body, it is difficult to handle the mounting board, and a large mounting space is required on the circuit board, which is not suitable for high-density mounting. .
[0013]
[Means for Solving the Problems]
The present invention has taken the following measures in order to solve the above points.
That is, first, a hollow portion having an inner bottom surface for mounting a semiconductor chip, a lead for realizing electrical conduction between the semiconductor chip mounted in the hollow portion and the outside of the package, and a resin body forming the package body In the package for mounting a semiconductor chip, the lead is obtained by cutting and bending a conductive metal plate, one end of which is exposed to the hollow portion, and a middle portion is embedded in the resin body, The other end was formed so as to be exposed to the outside on one surface of the resin main body from the vicinity of the periphery thereof.
[0014]
Here, the flush state means that a part of the upper surface or the lower surface of the resin body is formed.
With such a structure, in particular, by exposing the tip of the other end of the lead to the outside substantially flush with the surface of the resin body, electrical conduction with the electrode of the circuit board can be performed without processing the exposed lead. Therefore, a highly reliable semiconductor chip mounting package can be provided efficiently.
[0015]
Here, the semiconductor chip to be mounted later may have any circuit such as a solid-state imaging device, a microprocessor, a logic circuit, and a memory. Further, in the case of a solid-state imaging device, it is desirable that the lid for sealing the hollow portion later be made of a material such as glass that has a light transmitting property.
[0016]
Resin body epoxy resin, polyimide resin, phenol resin, unsaturated polyester resin, thermosetting resin such as a silicone resin or a liquid crystal polymer, polyphenylene oxide, polyphenylene sulfide (PPS) resin, polysulfone, polyamides-imides, polyallyl It is desirable to be molded with a heat-resistant thermoplastic resin such as a sulfone resin. Among them, epoxy resin, polyimide resin, PPS and the like are particularly preferable. The epoxy resin, particularly it is possible to use bisphenol A type, cresol novolak type, biphenyl type, naphthalene type, epoxy resins such as glycidyl amine type. The polyimide resin, specifically it is possible to use polyamino bi Sumareimido, Poripirome Li Ttoimido, polyimide resins such as polyether imide.
[0017]
An inorganic filler may be added to these heat-resistant resins. As the inorganic filler, an alumina powder, silica powder, silicon nitride powder, boron nitride Lai de powder, titanium oxide powder, silicon carbide powder, glass fibers, heat-resistant inorganic filler, such as alumina fibers and the like. Among these, alumina powder, silica powder, silicon nitride powder, and boron nitride powder are more preferable. The particle size of the inorganic filler is 0.1 to 100 μm, preferably 1 to 40 μm. The inorganic filler is added in an amount of 40 to 1900 parts by weight, preferably 100 to 900 parts by weight, based on 100 parts by weight of the heat-resistant resin. Further, in addition to the inorganic filler, if necessary, additives such as a curing agent, a curing accelerator, and a coupling agent may be contained.
[0018]
The leads are provided in the form of a lead frame and are preferably formed of a material selected from the group consisting of copper, iron, aluminum or alloys thereof, particularly a 42 alloy or a copper alloy such as phosphor bronze. The lead frame does not need to be subjected to any particular surface treatment, but may be subjected to a full or partial surface treatment if necessary, for example, may be plated with gold, silver, nickel, solder or the like. As the plating, nickel plating not containing a brightener such as saccharin can be used, and a brightener may be added to smooth the plating surface. In the case of a hollow package structure, an island portion on which a semiconductor chip is mounted is unnecessary, but the island portion may be embedded in a resin body and used as a moisture-resistant plate. Further, a semiconductor chip may be joined to the island portion in the hollow portion in the same manner as a normal lead frame. In this case, another material such as copper may be bonded in advance to the island portion in order to improve heat dissipation.
[0019]
Secondly, the other end of the lead is located on one surface of the resin main body substantially equal to or inward of the periphery thereof.
Accordingly, the lead does not protrude from the resin body to the outside, so that deformation and damage of the lead during handling can be prevented.
[0020]
Third, the other end of the lead was inclined to one surface of the resin body and exposed to the outside.
As described above, in addition to forming the other end of the lead flush with the resin body, the lead can be exposed to the outside in an inclined state.
[0021]
By inclining in this way, a joining material such as solder enters the inclined portion, and joining reliability can be improved. In particular, solder is effective because it has a high surface tension at the time of melting.
[0022]
Fourth, the other end of the lead may be exposed to the outside from either the outer bottom surface on the inner bottom surface side of the resin body on which the semiconductor chip is mounted, or the opening surface above the semiconductor chip.
[0023]
Thereby, various mounting forms can be realized.
Fifth, in manufacturing a semiconductor package, a lead frame that has been bent in advance is placed on a mold, and a thermoplastic resin or a thermosetting resin is injected into the mold to have a hollow portion. One end of the lead frame is exposed in the hollow portion, and the other end is formed to the outside of the resin body. The other end of the lead frame protruded outward from the periphery on one surface of the resin body. The tip was cut off.
[0024]
By forming the resin main body after bending the lead frame in advance in this way, stress on the resin main body due to the processing of the lead frame is eliminated, thereby preventing appearance defects and deterioration of moisture resistance due to cracks in the resin main body. Is done.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a lead frame 11 as shown in FIG. 5 is prepared. This lead frame can be obtained by processing a thin metal plate made of a copper alloy such as 42 alloy or phosphor bronze into a predetermined shape. In this embodiment, there is no island part, but a structure having an island part may be used.
[0026]
The lead frame 11 includes an inner lead 12 (one end) whose ends are independent from each other, and an outer lead 13 (the other end) which is connected to each other in the state of FIG. ing.
[0027]
As shown in FIG. 6, such a lead frame 11 is bent in a step-like manner at an intermediate portion 14 between the inner lead 12 and the outer lead 13. That is, it is bent once outward in the diagonal downward direction in the figure outside the inner lead 12, and further outwardly bent outward in the figure.
[0028]
The bent shape may be realized by a single press process using a pressing force using a mold, or may be realized by two separate press processes.
At this time, when the outer lead frame 11 is bent, as shown on the right side of FIG. 6, the outer lead 13 is bent so as to be substantially parallel to the inner lead 12, but is shown on the left side of FIG. As described above, the outer lead 13 may be bent so as to have a constant inclination angle θ with respect to the parallel line of the inner lead 12.
[0029]
Next, a resin main body 15 as shown in FIG. 7 is formed on the lead frame 11. The resin body 15 is formed by insert molding in which the lead frame 11 is mounted on a mold (not shown) and a resin such as epoxy resin is injected into the cavity of the mold at a high pressure.
[0030]
The conditions of the insert molding are different depending on the resin to be used. In the case of an epoxy resin, for example, under the conditions of a normal pressure of 10 to 800 kg / cm ² , a temperature of 130 to 200 ° C. and a time of 20 seconds to 5 minutes. Pressure heating is performed. It is desirable to add a post-curing step as needed.
[0031]
As shown in FIG. 7, the resin body 15 thus obtained has a hollow portion, and an inner bottom surface 17 of the hollow portion functions as a bonding surface for bonding the semiconductor chip 5. The inner wall of the hollow portion has a step in which the cross section on the inner bottom surface side has a small area and the upper opening side has a large area, and the inner lead 12 of the lead frame 11 is hollow at the shoulder of the step. Part is exposed.
[0032]
The middle part 14 of the lead frame 11 is buried in the resin body 15. Further, the tip of the outer lead 13 is exposed to the outside substantially in the same plane as the outer bottom surface near the periphery of the outer bottom surface 18 constituting one surface of the resin body 15. In the state shown in FIG. 7, the tip of the outer lead 13 is connected to the tips of the other outer leads.
[0033]
By cutting the leading end of the outer lead 13, the leads are electrically insulated from each other and become independent leads. Further, at this time, by cutting the foremost portion of the outer lead 13 along the periphery of the resin main body 15, the cut outer lead 13 can be formed so as not to protrude outward from the periphery of the resin main body. .
[0034]
Further, it is a matter of course that the cut portion of the outer lead 13 may be located outside the peripheral edge of the resin body 15.
The procedure for mounting a semiconductor chip on the semiconductor chip mounting package thus obtained and mounting it on a circuit board will be described below.
[0035]
First, the semiconductor chip 5 is mounted on the inner bottom surface 17 of the hollow portion of the resin body 15 with an adhesive. At this time, a metal such as gold, silver, or copper may be applied to the inner bottom surface 17 in advance in order to enhance adhesiveness and thermal conductivity. In addition, a technique such as ultrasonic bonding may be used instead of the adhesive.
[0036]
The semiconductor chip 5 used here is, for example, a solid-state imaging device such as a CCD (Charge-Coupled Device) used for a video camera or the like, but may be a logic circuit or a memory used for other purposes.
[0037]
Next, an electrode (not shown) of the semiconductor chip 5 and the surface of the inner lead 12 exposed in the hollow portion are electrically connected to each other by forming a wire made of a fine wire of gold or aluminum into a loop. For this, a known wire bonding technique can be used.
[0038]
Next, a lid 20 made of a glass plate is attached to the upper surface of the hollow portion to hermetically seal the inside of the hollow portion. The mounting of the lid 20 is performed by applying an adhesive to the peripheral edge of the opening on the outer upper surface of the resin main body 15 and mounting the lid 20.
[0039]
The semiconductor device thus obtained has a structure in which the tip of the outer lead 13 is exposed substantially flush with the outer bottom surface 18 in the vicinity of the periphery of the outer bottom surface 18 of the resin main body 15, so that the Handling at the time of mounting is easy. In addition, since the lead is bent before forming the resin body 15, the bending accuracy of the lead can be maintained higher than in the conventional technique in which the lead is bent after the resin body is formed. No pressure.
[0040]
Furthermore, since the cutting of the tip of the outer lead can be performed along the package periphery of the resin body 15, the mounting area on the circuit board can be reduced, and high-density mounting can be realized.
[0041]
Further, by providing an inclination angle θ at the bent portion of the outer lead 13, as shown in FIG. 10, a gap portion 21 having a triangular cross section is formed between the tip of the lead and the surface of the circuit board. The joining precision can be improved by using the tension to allow the solder to enter.
[0042]
In the present embodiment, an example in which the tip of the outer lead 13 is exposed to the outside from the outer bottom surface 18 of the resin body 15 has been described. However, as shown in FIG. It may be configured to be exposed from. Also in this case, as shown in the left part of FIG. 9, the tip of the outer lead 13 may be bent at a constant inclination angle θ.
[0043]
In the description of the embodiment, the case where the inclination angle θ is previously inclined when the lead frame is bent as shown in FIG. 6 has been described. However, when the distal end portion of the outer lead 13 described in FIG. Alternatively, the cutting die may be inclined by pressing force from above.
[0044]
【The invention's effect】
According to the present invention, it is possible to provide a semiconductor chip mounting package and a semiconductor device which have high bonding reliability to a circuit board, are suitable for high-density mounting, and are easy to handle.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a lead frame for explaining a conventional technique; FIG. 2 is a cross-sectional view showing a state where a semiconductor chip is mounted on a lead frame for explaining a conventional technique; FIG. FIG. 4 is a cross-sectional view showing a state in which a resin body is formed on a lead frame for use in the present invention. FIG. 4 is a cross-sectional view showing a state in which lead processing of a lead frame is performed for explaining a conventional technique. FIG. 6 is a cross-sectional view showing a state in which the lead frame of the embodiment is bent. FIG. 7 is a cross-sectional view showing a state in which a resin body is formed on the lead frame of the embodiment. FIG. 8 is a semiconductor device of the embodiment. FIG. 9 is a cross-sectional view showing a completed state of FIG. 9. FIG. 9 is a cross-sectional view showing a modification of the embodiment. FIG. 10 is a partial cross-sectional view showing a state where the semiconductor device of the embodiment is mounted on a circuit board.
1 Lead frame 2 Island part 3 Inner lead 4 Outer lead 5 Semiconductor chip 6 Wire 7 Resin body 11 Lead frame 12 Inner lead 13 Outer lead 14 ..Intermediate part 15, resin body 17, inner bottom surface 18, outer bottom surface 20, lid body 22, outer upper surface

Claims (12)

In a semiconductor chip mounting package for mounting a semiconductor chip which is a solid-state imaging device,
A resin body constituting the package body,
An inner bottom surface of the resin main body formed on the bottom side of the hollow portion formed in the resin main body for mounting the semiconductor chip,
A lead for realizing electrical conduction between the semiconductor chip mounted on the inner bottom surface and the outside of the package body,
A semiconductor chip mounting package comprising:
The lead is obtained by cutting and bending a conductive metal plate, one end of the lead is exposed to the hollow portion, an intermediate portion is buried in the resin body, and the other end is the resin body. A semiconductor chip mounting package, which is exposed to the outside on one surface substantially in a plane from the periphery thereof. 2. The package for mounting a semiconductor chip according to claim 1, wherein the other end of the lead is located on one surface of the resin main body substantially equal to or inward of a peripheral edge thereof. The semiconductor chip mounting package according to claim 1, wherein the other end of the lead is exposed to the outside while being inclined with respect to one surface of the resin body. 2. The semiconductor chip mounting package according to claim 1, wherein the one surface of the resin body from which the other end of the lead is exposed to the outside is an outer bottom surface located on the inner bottom surface side of the hollow portion. 2. The semiconductor chip mounting package according to claim 1, wherein one surface of the resin body from which the other end of the lead is exposed to the outside is an opening surface located on the opening side of the hollow portion. A resin body constituting the semiconductor device;
A semiconductor chip that is a solid-state imaging device;
An inner bottom surface of the resin main body formed on the bottom side of the hollow portion formed in the resin main body for mounting the semiconductor chip,
An electrode provided on the surface of the semiconductor chip and one end thereof are electrically connected, an intermediate portion thereof is embedded in the resin main body, and the other end is formed on one surface of the resin main body substantially in the vicinity of the periphery thereof. A lead made of a conductive metal plate exposed to the outside in one state,
A semiconductor device comprising: a lid mounted on the resin body to seal a hollow portion in which the semiconductor chip is mounted. 7. The semiconductor device according to claim 6, wherein the lid is a plate material having a light transmission characteristic. 7. The semiconductor device according to claim 6, wherein the other end of the lead is located substantially equal to or inward of a peripheral edge on one surface of the resin body. 9. The semiconductor device according to claim 6, wherein the other end of the lead is exposed to the outside while being inclined with respect to one surface of the resin body. 7. The semiconductor device according to claim 6, wherein one surface of the resin body from which the other end of the lead is exposed to the outside is an outer bottom surface located on the inner bottom surface side of the hollow portion. 7. The semiconductor device according to claim 6, wherein one surface of the resin body from which the other end of the lead is exposed to the outside is an opening surface located on the opening side of the hollow portion. Place the lead frame that has been bent beforehand on the mold,
A thermoplastic resin or a thermosetting resin is injected into the mold, and an inner bottom surface for mounting a semiconductor chip, which is a solid-state imaging device, at the bottom of a hollow portion formed in the resin is formed in the resin. Forming a resin body in which one end of the lead frame is exposed in the hollow portion and the other end is exposed to the outside,
A method of manufacturing a semiconductor package, comprising cutting and removing the tip of the other end of a lead frame protruding outward from a peripheral edge on one surface of the resin body.

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