JP2001094026A - Lead frame and manufacturing method thereof - Google Patents

Abstract

(57) [Problem] To provide a lead frame which can secure a predetermined strength even if it is made thinner, does not require a carrier for conveyance, and has a low cost, and a method for manufacturing the same. SOLUTION: A package forming area 3 partitioned by providing a frame 4 around an inner side of a conductive substrate 2, and a thickness of about 1 of the thickness of the substrate 2 in both sides of the package forming area 3 in the package forming area 3. /
Bonding pads 6 and ball pads 7 provided on both main surfaces by half-etching or the like by a predetermined pattern to a depth of approximately 1/3 of the thickness of the substrate 2 so as to leave the wiring leads 8 and the connection leads 9 having a thickness of 3 mm. And a solder resist 10 in which an etched portion is buried to both main surface positions. Each of the bonding pads 6 and the ball pad 7 is provided between the two main surfaces.
Wiring leads 8 so that the corresponding pads make a pair.
And is connected to the frame portion 4 by the connection lead 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin BGA
The present invention relates to a lead frame suitable for a package and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, BGA (Ball Grid A)
(rray) In a package or the like, a high-density wiring is used. Therefore, a glass-epoxy substrate (a glass cloth base epoxy resin substrate) or a polyimide film is used as a base material.
As a conductive film on both front and back surfaces, for example, using a wiring board in which copper foil is bonded, the front and back conductive films are patterned so as to have a predetermined pattern, and a through hole is provided to provide conduction between predetermined portions of the front and back patterns. I am taking it. That is, a ball pad is formed on the back surface corresponding to the bonding pad formed on the front surface for mounting the semiconductor chip, and a through hole penetrating the bonding pad and the ball pad is processed by a drill, a laser or the like, and the formed through hole is further formed. The holes are plated with Cu so that both pads are electrically connected.

However, according to the above-mentioned prior art, when the package is made thinner along with the miniaturization and thinning of the semiconductor device, it is naturally necessary to make the members thinner, and it is necessary to make the wiring board thinner. Become. If the wiring board has a small thickness of, for example, 0.1 mm or less, the strength decreases accordingly, and when the semiconductor chip is mounted and transported for packaging or the like, iron-nickel steel or stainless steel is used. Etc., and must be transported by being attached to a carrier for transportation.

[0004] As described above, in the case of performing double-sided wiring for high-density wiring, Cu plating must be performed in order to process through holes and to establish conduction between the front and back surfaces, which requires time and effort. If the wiring board is made thinner in response to the thinning of the semiconductor device, there will be a problem in strength, and it will be necessary to attach it to a carrier for transport and carry it again. There was a risk of it.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances. It is an object of the present invention to provide a semiconductor device having a predetermined strength even with a reduced thickness.
It is an object of the present invention to provide a lead frame and a method for manufacturing the same, which do not require a carrier carrier to be attached when carrying a semiconductor chip and transport the semiconductor chip, thereby reducing costs.

[0006]

According to the present invention, there is provided a lead frame and a method of manufacturing the same, comprising: a package forming region partitioned by providing a frame portion inside a conductive metal substrate; A conductive pattern of a predetermined pattern formed by cutting a substrate from both main surfaces to a predetermined depth so as to leave a wiring lead portion and a connection lead portion of a predetermined thickness, and providing a conductive portion on both main surfaces. And an insulating portion formed by burying an insulating material in the cut portion up to both main surface positions, and further,
The depth of the cut from both main surfaces and the thickness of the wiring lead portion and the connection lead portion are each approximately one-third the thickness of the metal substrate. The conductive portion has a plurality of conductive portions on both main surfaces, and the conductive portions between the two main surfaces are electrically connected to each other by a wiring lead portion such that corresponding portions form a pair, and are connected. It is characterized in that it is connected to the frame portion by a lead portion, and that one main surface of the conductive metal substrate is half-etched to a predetermined depth so that a conductive portion of a predetermined pattern is formed. Forming a conductive portion on the surface, embedding an etched portion of one half-etched main surface of the metal substrate with an insulating material and providing a protective film over the entire main surface, and forming the other main surface of the metal substrate at a predetermined depth. Haha Etching process to form a conductive portion of the conductive portion on the other main surface, forming a conductive portion on the other main surface, forming an etching resistant film of a predetermined pattern and etching from the other main surface to conduct to the conductive portion Forming a wiring lead portion and a connection lead portion having predetermined thicknesses, and removing a protective film on one main surface after embedding an etched portion from the other main surface side of the metal substrate with an insulating material. A half-etching dimension from both main surfaces, and a thickness dimension of a wiring lead portion and a connection portion are each approximately 1/3 of a thickness of the metal substrate. In addition, the insulating material filling the etched portion is a solder resist,
The method is characterized in that the protective film is a dry film.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The following is an embodiment of the present invention, B
A lead frame of a ball grid array (GA) package will be described with reference to FIGS. FIG. 1 is a partial sectional view showing a first step, FIG. 2 is a partial sectional view showing a second step, FIG. 3 is a partial sectional view showing a third step, and FIG. 5 is a partial sectional view showing a fifth step, FIG. 6 is a partial plan view showing the fifth step, and FIG. 7 is a plan view of a lead frame. FIG. 8 is a partial plan view showing a state where a semiconductor chip is mounted.

First, in FIGS. 1 to 8, reference numeral 1 designates a lead frame formed in a strip shape having a predetermined size, for example, a copper or copper alloy substrate 2 having a plate thickness of 0.1 mm or less.
A plurality of package forming regions 3 for forming a BGA package in an inner portion are partitioned so as to provide a frame portion 4 around the package forming region 3. In each of the package forming regions 3, a bonding pad 6 to which a bonding wire 5 is connected on the upper surface side as a conductive portion and a B formed on the lower surface side are formed.
A conductive portion of a ball pad 7 for mounting a GA package, a wiring lead 8 for conducting both pads 6, 7, and a connection lead 9 for connecting the wiring lead 8 to the frame 4.
Is formed by half-etching the substrate 2 into a predetermined pattern or by etching the substrate 2 in a thickness direction.

Further, in a portion of the package forming region 3 where the half-etching or the like has been performed, a solder resist 10 such as, for example, an arylate resin is buried so as to have substantially the same thickness as a whole. Thereby, the lead frame 1
The bonding pad 6 and the ball pad 7 are exposed on the upper surface and the lower surface, respectively, and the nickel (Ni) / gold (Au) plating 11a and 11b are provided on the exposed surface of the bonding pad 6 and the ball pad 7, respectively. Will be applied.

The semiconductor chip 1 is provided in each package forming region 3 of the lead frame 1 formed as described above.
2 is die-bonded and then the semiconductor chip 12
The electrode 13 and the bonding pad 6 are connected by bonding both ends of the bonding wire 5 respectively. A package 14 made of a synthetic resin is molded on the lead frame on which the semiconductor chip 12 is mounted in such a manner that an outer edge is located at an intermediate portion of the connection lead 9. Further, the lead frame 1 on which the package 14 is molded is cut at the outer edge of the package 14 and separated into the frame 4 side and the package 14 side, thereby forming a BGA package.

Next, a method of manufacturing the lead frame 1 will be described. First, in a first step shown in FIG. 1, a dry film 15 made of, for example, a film, a heat-sensitive layer or the like and having a thickness of about 25 to 50 μm is formed on both surfaces of the substrate 2.
a and 15b are attached by a method such as thermocompression bonding. Subsequently, a photoresist (not shown) is applied to the surface of the dry film 15a on the upper surface side, and the applied photoresist is patterned by photolithography to form a mask having a predetermined pattern by the dry film 15a. Thereafter, using the formed mask, the substrate 2 is half-etched from the upper surface side to a predetermined depth, for example, about ３ of the plate thickness, using, for example, cupric chloride as an etchant. Thereby, the frame portion 4 is formed around the upper surface side of the package formation region 3.
Forming region 3 while providing the upper surface side of
A bonding pad 6 is formed therein.

Next, in a second step shown in FIG. 2, the mask made of the dry film 15a on the upper surface of the substrate 2 is removed, and a solder resist 10 made of, for example, an acrylate resin is placed on the half-etched portion. It is buried so that the upper surface is substantially flat. Subsequently, a dry film 16 of the same material as that previously attached is again adhered to the entire upper surface in which the solder resist 10 is embedded by thermocompression bonding or the like.

Next, in a third step shown in FIG. 3, a photoresist (not shown) is applied to the surface of the dry film 15b on the lower surface side, and the applied photoresist is patterned by photolithography to form a predetermined pattern. A mask using the film 15b is formed. Thereafter, using the formed mask, the substrate 2 is half-etched from the lower surface side to a predetermined depth, for example, a depth of about ３ of the plate thickness. Thus, the ball pad 7 is formed in the package forming region 3 while the lower surface of the frame portion 4 is provided around the lower surface of the package forming region 3.

Next, in a fourth step shown in FIG. 4, the mask made of the dry film 15b on the lower surface of the substrate 2 is removed, and the etching resistance of, for example, a casein-based material is again applied to the entire lower surface of the substrate 2. A resist 17 is applied and patterned to form a mask of a predetermined pattern of the resist 17 for forming the wiring leads 8 and the connection leads 9. Thereafter, using the formed mask, the substrate 2 is etched so as to penetrate from the lower surface side to the upper surface side, and the wiring leads 8 connecting the bonding pads 6 and the ball pads 7 and the frame portion 4 are formed.
Then, a connection lead 9 for connecting the wiring lead 8 is formed. Further, a solder resist 10 is buried in a portion of the substrate 2 which has been half-etched and etched to penetrate the substrate 2 so that the lower surface is substantially flat.

Next, in a fifth step shown in FIG. 5, the dry film 16 and the resist 17 on the upper and lower surfaces of the substrate 2 are removed. Then, nickel (Ni) / gold (Au) is applied to the exposed surfaces of the bonding pad 6 and the ball pad 7.
The lead frame 1 is formed by applying the platings 11a and 11b.

Since the lead frame 1 is formed as described above, the strength of the formed lead frame 1 is relatively strong because the four circumferences of the package forming region 3 are surrounded by the thick frame portion 4. Thus, even when the substrate 2 is thinned, the substrate 2 can be transported without using a transporting carrier, so that the substrate 2 can be easily handled. Then, since the package can be made thin, the semiconductor device can be easily made thin. Further, the package forming region 3 is provided with bonding pads that are electrically connected to each other for double-sided wiring without performing complicated processing using a drill or a laser or performing cumbersome Cu plating for conduction between the front and back surfaces of the processed holes. 6 and the ball pad 7 can be easily formed, high-density wiring can be performed without performing complicated processing and processing, and without increasing the manufacturing cost.

[0017]

As is apparent from the above description, according to the present invention, it is possible to reduce the thickness while maintaining a predetermined strength, and to provide a semiconductor chip or the like mounted on a semiconductor chip or the like because of having the predetermined strength. When transporting by means of, there is no need to attach a carrier for transporting, so that there is an effect that labor is not required and cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a first step in one embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing a second step in one embodiment of the present invention.

FIG. 3 is a partial sectional view showing a third step in one embodiment of the present invention.

FIG. 4 is a partial sectional view showing a fourth step in one embodiment of the present invention.

FIG. 5 is a partial cross-sectional view showing a fifth step in one embodiment of the present invention.

FIG. 6 is a partial plan view showing a fifth step in the embodiment of the present invention.

FIG. 7 is a plan view of a lead frame according to the embodiment of the present invention.

FIG. 8 is a partial plan view showing a state where a semiconductor chip according to one embodiment of the present invention is mounted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 2 ... Substrate 3 ... Package formation area 4 ... Frame part 6 ... Bonding pad 7 ... Ball pad 8 ... Wiring lead 9 ... Connection lead 10 ... Solder resist 12 ... Semiconductor chip 14 ... Package 15a, 15b, 16 ... Dry film 17 ... Resist

Claims (6)

[Claims] 1. A package forming area defined by providing a frame around the inside of a conductive metal substrate, and a wiring lead portion having a predetermined thickness from both main surfaces in the package forming area. A conductive portion of a predetermined pattern formed by cutting a predetermined depth so as to leave a connection lead portion and providing a conductive portion on both main surfaces; A lead frame comprising: an insulating portion buried to a position. 2. The method according to claim 1, wherein the depth of the cut from both main surfaces and the thickness of the wiring lead portion and the connection lead portion are approximately one third of the thickness of the metal substrate. The lead frame according to claim 1. 3. The conductive portion has a plurality of conductive portions on both main surfaces, and the conductive portions between the two main surfaces are electrically connected by a wiring lead portion such that the corresponding portions form a pair. 2. The lead frame according to claim 1, wherein the lead frame is connected to the frame by a connection lead portion. 4. A step of half-etching one main surface of the conductive metal substrate to a predetermined depth so as to form a conductive portion of a predetermined pattern to form a conductive portion on the one main surface, and half-etching the metal substrate. Burying the etched portion of the one main surface with an insulating material and providing a protective film on the entire surface of the one main surface, and half-etching the other main surface of the metal substrate to a predetermined depth to form the conductive portion of the conductive portion on the other main surface. Forming a portion, forming the conductive portion on the other main surface, forming an etching resistant film of a predetermined pattern, etching from the other main surface side, and connecting the wiring lead portion having a predetermined thickness to conduct to the conductive portion; Forming a lead portion, and removing the protective film on one main surface after embedding an etched portion from the other main surface side of the metal substrate with an insulating material. Lead frame manufacturing method. 5. The semiconductor device according to claim 4, wherein the half-etched dimension from both main surfaces and the thickness dimension of the wiring lead portion and the connection portion are approximately one third of the thickness of the metal substrate. The method for manufacturing the lead frame described in the above. 6. The method for manufacturing a lead frame according to claim 4, wherein the insulating material filling the etched portion is a solder resist, and the protective film is a dry film.