JPH11340404A - Lead frame and manufacture of plastic package using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which a plastic package can be manufactured with high workability and inexpensively. SOLUTION: A lead frame 2 is used at the time of performing such an insert molding that the molded surface in a parts housing space formed of a molding resin 5 and the external surface of an inner lead section 3 are flush with each other. At a prescribed position in the inner lead section 3, a ruggedness structure 11 is formed for preventing the formation of molding burrs. After the insert molding is performed with the use of the lead frame 2, a conductor 9 is bonded to a region where the recessing and projecting structure 11 is formed by using the region as a conductor bonding area B1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lead frame and a method for manufacturing a plastic package using the same.

[0002]

2. Description of the Related Art Conventionally, a method of manufacturing a plastic package using a lead frame has been known. An example is briefly described below.

First, a lead frame having an inner lead portion, an outer lead portion and an island portion is manufactured by etching or punching a metal plate material.
The lead frame is set in a predetermined mold, and insert molding is performed using a mold resin. At this time, a cavity which is a space for accommodating the semiconductor chip is formed in a part of the mold resin. An island portion is located at the center of the bottom surface of the cavity, and the inner lead portion is located so as to surround the island portion. Next, the island portion is used as a die area, and a semiconductor chip is die-bonded thereon. Furthermore, the semiconductor chip side is the primary side and the inner lead portion is the secondary side,
Wire bonding is performed by a wire bonder. As a result, the two are electrically connected via the bonding wire, and the package is completed when the cap is put on the two.

[0004]

However, in the conventional method, insert molding is performed so that the molding surface in the cavity and the outer surface of the inner lead portion are the same, so that the molding resin from the interface is removed. By oozing,
Thin skin-like molding burrs are likely to occur in the cavity. Therefore, the molding flash may adhere to the surface of the bonding area in the inner lead portion. Then, the area is partially insulated, and the secondary side end of the bonding wire cannot be reliably joined by the ordinary wedge bonding method, resulting in a problem that connection reliability is reduced.

Therefore, in order to avoid the above problem,
It was necessary to carry out deburring work by liquid honing and the like. However, in this case, the number of man-hours is inevitably increased, so that the deterioration of workability is inevitable. Also,
The necessity of a special deburring device also raises the problem that the manufacturing cost increases.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing a plastic package which is excellent in workability and cost. Another object of the present invention is to provide a method of manufacturing a plastic package that can easily obtain a product having excellent connection reliability.

Another object of the present invention is to provide a lead frame suitable for manufacturing such a package.

[0008]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, a molding surface in a component accommodating space formed by a mold resin and an outer surface of an inner lead portion are provided. The gist of the present invention is a lead frame which is used when performing insert molding such that the same surface is formed, and in which a concave and convex structure for preventing molding flash adhesion is formed at a predetermined position in the inner lead portion.

According to a second aspect of the present invention, in the first aspect, the uneven structure is an annular uneven structure surrounding a conductor bonding area in the inner lead portion. According to a third aspect of the present invention, in the second aspect, the size of the annular concavo-convex structure is equivalent to about half of the thickness of the inner lead portion.

According to a fourth aspect of the present invention, in the second or third aspect, the annular concave-convex structure is an annular groove.
According to a fifth aspect of the present invention, in the second or third aspect,
The annular uneven structure was an annular ridge.

[0011] The invention described in claim 6 is the first to fifth aspects.
A method for manufacturing a plastic package, comprising: after performing insert molding using the lead frame according to any one of (1) to (4), setting an area in which the uneven structure is formed as a conductor joining area and joining a conductor thereto. The method is the gist.

The "action" of the present invention will be described below. According to the first aspect of the invention, even if the uncured mold resin oozes out from the interface between the molding die and the lead frame during insert molding, its progress is prevented by the presence of the uneven structure. Therefore, the mold resin cannot reach the area where the uneven structure is formed, and as a result, the skin-like molding flash is less likely to adhere to a predetermined area in the inner lead portion. Therefore, it is not necessary to deburr the conductor bonding area after the insert molding, so that an increase in man-hour is avoided and workability is improved. Further, a special deburring device is not required, which is advantageous in terms of cost.

According to the second aspect of the present invention, since the conductor bonding area is surrounded by the annular uneven structure, the conductor bonding area can be reliably protected regardless of the direction of entry of the uncured mold resin. it can.

According to the third aspect of the present invention, if the size of the annular concavo-convex structure corresponds to about half the thickness of the inner lead portion, it can be relatively easily formed by, for example, a general half-etch method. In addition, a lead frame having a desired shape can be manufactured at low cost.

According to the fourth aspect of the present invention, when the uncured mold resin oozing out from the interface reaches the annular groove from the outside, the mold resin enters the annular groove, so that the flow resistance sharply increases there. Increase. Therefore, further progress of the mold resin is prevented. In addition, if a concave structure such as an annular groove is used, a lead frame can be manufactured at lower cost.

According to the fifth aspect of the present invention, when the uncured mold resin oozing out from the interface reaches the annular ridge from the outside, the flow resistance sharply increases there due to the presence of the annular ridge. Therefore, the mold resin cannot travel over the annular ridge, and further progress of the mold resin is prevented.

According to the sixth aspect of the present invention, since the conductor can be joined to a suitable conductor joining area where there is no skin-like molding flash, a package having excellent connection reliability can be easily and reliably provided. Can be manufactured. Also,
In the manufacturing method of the present invention, since the insert molding is performed using the lead frame according to any one of claims 1 to 5, it is of course excellent in workability and cost.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention embodied in a method for manufacturing a plastic package 1 for a CCD will be described in detail below with reference to FIGS.

As shown in FIG. 1, the plastic package 1 of the present embodiment is a so-called DIP type package 1 in which an outer lead portion 4 projects from two side surfaces.

The lead frame 2 constituting the package body is made of a conductive metal and has an inner lead portion 3 and an outer lead portion 4. A plurality of inner lead portions 3 and outer lead portions 4 are formed. The outer lead portions 4 protrude in parallel from two sides of the mold resin 5 constituting the package body toward the outside. These outer lead portions 4 are bent at substantially right angles toward the lower surface of the package 1.

On the upper surface of the rectangular mold resin 5,
A cavity 7 for accommodating a CCD chip 6 as an electronic component is formed. The cavity 7, which is a component accommodating space, is formed simultaneously with insert molding. The center of the bottom surface of the cavity 7 is a die area D1. In the cavity 7, a pair of steps 7a facing each other across the die area D1 are formed.

The inner lead portion 3 is located on the upper surface of these steps 7a. The upper surface of the step portion 7a, which is a molding surface, and the upper outer surface of the inner lead portion 3 are flush with each other. Note that the inner lead portion 3 may be subjected to nickel-gold plating or the like as necessary.

On the die area D 1 in the cavity 7,
The CCD chip 6 is die-bonded with the adhesive 8. The CCD chip 6 is provided with a plurality of pads (not shown) on the periphery of the upper surface.

The pads on the CCD chip 6 and the conductor bonding area (ie, the bonding area B1 in this case) in each inner lead portion 3 are bonded via bonding wires 9, respectively. As a result, CC
The D chip 6 side and the package body side are electrically connected.

As shown in FIGS. 3 and 4, the lead frame 2 is provided with a concave-convex structure at a predetermined position in the inner lead portion 3 for preventing the formation of a flash. More specifically, the concave-convex structure in the present embodiment is an annular groove 11.

The annular groove 11 has a rectangular outer shape when the package 1 is viewed from above. As a result, a rectangular bonding area B1 is secured in the area where the annular groove 11 is formed.
That is, the bonding area B1 is completely surrounded by the annular groove 11.

The long sides of the rectangle are parallel to the length direction of the inner lead portion 3, and the short sides are parallel to the width direction of the inner lead portion 3. The long side of the annular groove 11 is set to about half the length of the inner lead portion 3,
The short side of the annular groove 11 is set slightly shorter than the width of the inner lead portion 3 (see FIG. 3). It is preferable that the short side of the annular groove 11 is set to be at least several times larger than the diameter of the bonding wire 9 which is a conductor to be joined thereto.

In this embodiment, the thickness of the inner lead portion 3 of the lead frame 2 is set to about 0.25 mm. The size (specifically, the depth) of the annular groove 11 is 0.10 mm to 0.15 mm, that is, the inner lead portion 3.
Is set to about half of the thickness.

The width of the annular groove 11 ranges from 0.1 mm to 0.1 mm.
It may be set to 2 mm. The width is 0.2m
If it is larger than m, the bonding area B1 having a certain area may not be secured. If the width is set to be smaller than 0.1 mm, the progress of the uncured mold resin 5 may not be reliably prevented.

Next, an example of a procedure for manufacturing the plastic package 1 according to the present embodiment will be described with reference to FIGS. First, the lead frame 2 is manufactured according to the following procedure according to FIG. A conductive metal plate material 12 for forming a lead frame such as 42 alloy or Kovar is prepared, and both surfaces are etched with an etching resist 13 provided on both surfaces (see FIGS. 5A to 5C). as a result,
A predetermined portion of the metal plate 12 is completely etched and removed, and the annular groove 1 which is a half-etched portion is provided at the predetermined portion.
1 is formed. Unnecessary etching resist 13
Is removed later using a dedicated stripper or the like. According to this method, it is also possible to form the annular grooves 11 on both surfaces of the metal plate 12 as in a lead frame 2A shown in FIG.

Next, the completed lead frame 2 is set in a mold (not shown), and insert molding is performed using the mold resin 5. As the mold resin 5, for example, a thermosetting epoxy resin is used. A thermosetting polyimide resin or the like may be used. When such insert molding is performed, the cavity 7 is simultaneously formed in a part of the mold resin 5, but the thin-skin-shaped molding flash does not adhere to the bonding area B1 of the inner lead portion 3 exposed from the upper surface of the stepped portion 7a. .

That is, the uncured mold resin 5 oozing out from the interface with the mold is formed into the annular groove 11 from the outside.
Is reached, the mold resin 5 enters the annular groove 11, and the flow resistance increases sharply there. Therefore,
This is because further progress of the mold resin 5 is prevented.

In the next die bonding step, an adhesive 8 is applied to the die area D1 in advance, and the CCD chip 6 is die bonded by a die bonder. After the die bonding step, a wire bonding step is performed using a general wire bonder. As a result, each pad on the CCD chip 6 and the bonding area B1 of each inner lead portion 3 are bonded via the bonding wire 9 as a conductor.

After performing the wire bonding step in this manner, if necessary, if necessary, the cavity 7 is hermetically sealed by potting or the like, and the porous cap 10 is bonded to the upper opening. Package 1
Is completed.

Therefore, according to the present embodiment, the following effects can be obtained. (1) In the present embodiment, the annular groove 1 having a concavo-convex structure at a predetermined position in the inner lead portion 3 for preventing molding flash adhesion
Insert molding is performed using the lead frame 2 on which the lead frame 1 is formed. Therefore, even if the uncured mold resin 5 oozes out from the interface between the mold and the lead frame 2 during insert molding, its progress is prevented by the presence of the annular groove 11. Therefore, the mold resin 5 cannot reach the region where the annular groove 11 is formed, and as a result, the skin-like molding flash hardly adheres to a predetermined region of the inner lead portion 3. Therefore,
Deburring of the bonding area B1 after insert molding is not required, so that an increase in man-hours is avoided and workability is improved. Further, a special deburring device is not required, which is advantageous in terms of cost.

(2) Since the concave-convex structure is annular, the bonding area B1 is completely surrounded thereby. Therefore, the uncured mold resin 5
Irrespective of the direction of intrusion, the bonding area B1 can be reliably protected. That is, compared with the case where the uneven structure that is not completely annular is employed, the thin skin-shaped molding flash is less likely to adhere, which also contributes to improvement in workability and cost.

(3) In the lead frame 2 of the present embodiment, the depth of the annular groove 11 having the annular uneven structure corresponds to about half of the thickness of the inner lead portion 2.
Therefore, the lead frame 2 having a desired shape can be manufactured relatively easily and at low cost by a general half-etch method. This contributes to improvement in manufacturability and cost. In addition, if the concave structure like the annular groove 11 is used, the lead frame 2 can be manufactured at a lower cost than when a convex structure is temporarily formed by a half-etch method. In other words, the amount removed by etching is significantly smaller, and material is less wasted.

(4) In the manufacturing method of the present embodiment, a suitable bonding area B1 where there is no skin-like molding flash.
Can be bonded to the bonding wire 9. Therefore, there is no fear that the bonding area B1 is partially insulated by the presence of the molding flash. Therefore, the secondary end of the bonding wire 9 can be securely wire-bonded to the inner lead portion 3, and the package 1 having excellent connection reliability can be easily and reliably manufactured.

The embodiment of the present invention may be modified as follows. -It is good also as a lead frame 21 like another example shown in FIG. The concavo-convex structure of the lead frame 21 is not a concave structure as in the above embodiment, but a convex structure (specifically, an annular ridge 22). This annular ridge 2
2 is an outer shape when the package 1 is viewed from the upper surface direction.
For example, it is formed to have a rectangular shape as in the above embodiment. As a result, a rectangular bonding area B1 is secured in the region where the annular ridge 22 is formed. That is, the bonding area B1 is completely surrounded by the annular ridge 22.

The thickness of the lead frame 21 is about 0.25 m
m, the size (specifically, the height) of the annular ridge 22 and the thickness of the inner lead portion 3 are both 0.10 m.
It may be set to about m to 0.15 mm. This is because such a dimension setting is suitable for manufacturing the lead frame 21 by the half-etch method as in the above embodiment. The width of the annular ridge 22 is 0.1 mm.
It is good to set to ~ 0.2mm.

As in another example of the lead frame 31 shown in FIG. 7, a non-annular uneven structure (raised portion 32) can be formed, and the entire upper surface of the raised portion 32 can be used as the bonding area B1.

As in another example of the lead frame 41 shown in FIG. 8, as long as the surrounding space allows, it is preferable that the portion where the annular groove 11 is formed in the inner lead portion 3 be formed wide. . When formed in this way,
The distance from the uncured mold resin 5 that has exuded and advances to reach the annular groove 11 becomes longer in the first place, and it becomes more difficult for the skin-like molding flash to adhere to the bonding area B1.

The plastic package 1 is not limited to the DIP form as in the above-described embodiment, but may take various forms such as SIP, SOP, QFP, QFJ, and QFL.

Lead frames 2, 2A, 21, 31
The conductor bonding area secured by the concavo-convex structure in the inner lead portion 3 is not limited to the bonding area B1 as in the above embodiment. For example, it may be an adhesion / application area of a conductive adhesive,
Further, it may be a soldering area. Of course, the conductor bonded to such an area is not limited to only the bonding wire 9 as in the above embodiment. For example,
Chip components such as a chip resistor and a chip capacitor may be joined. Note that the cavity 7 itself formed in the mold resin 5 can also be configured to accommodate these chip components and the like.

Lead frames 2, 2A, 21, 31
Can be formed not only by etching but also by punching using, for example, a press.

For example, the lead frames 2, 2A, 2
In each of the inner lead portions 1 and 31, it is preferable to perform insert molding while pressing the back surface of the conductor bonding area secured by the uneven structure upward using a pin or the like made of metal or the like. Such a pin is removed after insert molding. The hole formed at the time of removal may be filled with an insulating material such as a resin. According to the method described above, the skin-like molding burr is more difficult to adhere to the conductor bonding area.

Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments will be enumerated below together with their effects as necessary. (1) The lead structure according to any one of claims 1 to 6, wherein the uneven structure is present on both front and back surfaces of the lead frame.

(2) The lead frame according to any one of claims 1 to 6, wherein the lead frame is manufactured by a half-etch method. Therefore, according to the invention described in the technical idea 2, it is possible to relatively easily produce a desired shape at low cost.

(3) In any one of claims 4 to 6, the width of the annular groove or the annular ridge is 0.1 m.
m to 0.2 mm. Therefore, this technical idea 3
According to the invention described in (1), by setting the width in the preferable range, it is possible to reliably prevent the progress of the uncured mold resin while securing the conductor bonding area of a certain area.

(4) In any one of claims 1 to 6, a portion where the uneven structure is formed in the inner lead portion is formed wider than other portions in the inner lead portion. thing. Therefore, according to the invention described in the technical idea 4, the thin skin-shaped molding beam is more difficult to adhere to the conductor joining area.

(5) In any one of claims 1 to 6, a chip component (for example, I
C chip, LSI chip, CCD chip, chip resistor,
Chip capacitors, chip conductors, chip coils, etc.).

(6) In claim 6, the insert molding is performed while pressing the back surface of the inner lead portion where the uneven structure is formed upward by using a pressing body. Therefore, according to the invention described in the technical idea 6, the skin-like molding burr is more difficult to adhere to the conductor joining area.

[0053]

As described in detail above, according to the first to fifth aspects of the present invention, deburring of the conductor bonding area after insert molding is not required, so that workability and cost performance are excellent. Thus, it is possible to provide a lead frame suitable for manufacturing the above-mentioned suitable plastic package.

According to the second aspect of the present invention, since the conductor bonding area is reliably protected regardless of the direction of entry of the uncured mold resin, the workability and cost can be further improved. it can.

According to the third aspect of the present invention, it is possible to manufacture a desired shape relatively easily and at low cost. According to the invention described in claim 4, a lead frame that can be manufactured at lower cost can be provided.

According to the sixth aspect of the present invention, there is provided a method of manufacturing a plastic package which is excellent in workability and cost, and which can easily obtain a package excellent in connection reliability. Can be provided.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a plastic package according to an embodiment of the present invention.

2A is a partial plan view of the package, and FIG. 2B is a schematic partial sectional view thereof.

FIG. 3 is a partially enlarged plan view of a bonding area of the package.

FIG. 4 is a partially enlarged sectional view of a bonding area of the package.

FIGS. 5A to 5D are partial cross-sectional views illustrating a procedure for manufacturing a lead frame.

FIG. 6 is a partially enlarged cross-sectional view of a bonding area of a package of another example.

FIG. 7 is a partially enlarged cross-sectional view of a bonding area of a package of another example.

FIG. 8 is a partially enlarged plan view of a bonding area of a package of another example.

[Explanation of symbols]

1: Plastic package, 2, 2A, 21, 3
1, 41: lead frame, 3: inner lead part, 5
... Mold resin, 7: Cavity as space for accommodating parts, 9 ... Bonding wire as conductor, 11 ... Circular groove as (annular) concavo-convex structure, 22 ... Circular ridge as (circular) concavo-convex structure, 32 ... Concavo-convex structure Ridge, B
1… A bonding area as a conductor bonding area.

Claims (6)

[Claims] 1. A lead frame used for performing insert molding such that a molding surface formed in a component housing space formed by a mold resin and an outer surface of an inner lead portion are flush with each other, A lead frame having a concavo-convex structure formed at a predetermined position in the inner lead portion to prevent adhesion of a molding flash. 2. The lead frame according to claim 1, wherein said uneven structure is an annular uneven structure surrounding a conductor bonding area in said inner lead portion. 3. The lead frame according to claim 2, wherein the size of said annular concave-convex structure is about half of the thickness of said inner lead portion. 4. The lead frame according to claim 2, wherein said annular concave-convex structure is an annular groove. 5. The lead frame according to claim 2, wherein said annular uneven structure is an annular ridge. 6. After performing insert molding using the lead frame according to any one of claims 1 to 5, an area in which the uneven structure is formed is used as a conductor joining area, and a conductor is joined thereto. A method of manufacturing a plastic package.