Lead frame

Abstract

This invention provides a lead frame and related products that can improve the reliability of semiconductor devices and other equipment. [Solution] By manufacturing semiconductor devices and other products using a lead frame that includes leads and is provided on the leads with intrusion prevention means, which are two or more stepped recesses that prevent flux and moisture from entering, the reliability of semiconductor devices and other products can be dramatically improved.

Description

Technical Field

[0001] The present invention relates to a lead frame useful for semiconductor devices and the like, and products thereof.

Background Art

[0002] Conventionally, lead frames used for semiconductor devices and the like have a great influence on the reliability of semiconductor devices and the like, and various studies have been made on their manufacturing methods and the like.

[0003] In recent years, a manufacturing method of a lead frame used for a non-leaded semiconductor device has been studied. In a non-leaded semiconductor device such as a QFN (Quad Flat Non-Leaded Package), in which the lower surface (external electrode terminal) of a lead is exposed on the mounting surface side of the package (the lower surface side of the resin sealing body), a retaining portion is formed by forming a part of the lower surface of the lead thin, and a mold lock portion is formed by the sealing resin flowing into the lower part of the retaining portion so that the lead does not fall off from the resin sealing body (package). (For example, see Patent Document 1)

[0004] However, none of the conventional methods can sufficiently prevent the intrusion of flux and moisture, and the reliability of semiconductor devices and the like is still not satisfactory.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a lead frame and a product thereof that can improve the reliability of semiconductor devices and the like.

Means for Solving the Problems

[0007] As a result of diligent research to achieve the above objective, the present inventors have found that a lead frame having a retaining portion at the lead end, wherein the retaining portion is further provided with an uneven surface consisting of a recess or a convex portion, can efficiently prevent flux and moisture from entering, and that such a lead frame can solve the above-mentioned conventional problems all at once. Furthermore, after obtaining the above findings, the inventors conducted further studies and completed the present invention.

[0008] In other words, the present invention relates to the following invention. [1] A lead frame having a retaining portion at the lead end, wherein the retaining portion is further provided with an uneven portion consisting of a recess or a protrusion. [2] The lead frame according to [1], wherein the uneven portion is provided on all or part of the back surface of the retaining portion. [3] The lead frame according to [1], wherein the retaining portion and the protrusions have a stepped shape of two or more steps. [4] The lead frame according to [1], wherein the uneven portion is located within the sealing resin. [5] The lead frame according to [1], wherein the uneven portion is shaped by deforming a part of the lead within the sealing resin. [6] The lead frame according to [1], wherein the uneven portion is a processed portion obtained by processing a part of the lead in the sealing resin. [7] An electronic device including a lead frame, wherein the lead frame is the lead frame described in [1]. [8] An electronic component including a lead frame, wherein the lead frame is the lead frame described in [1]. [9] A product comprising a lead frame, wherein the lead frame is the lead frame described in [1]. [Effects of the Invention]

[0009] The lead frame of the present invention can improve the reliability of semiconductor devices and the like. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing an example of a suitable lead of the present invention. [Figure 2] Figure 1 shows a modified example of the die pad. [Figure 3] This is a modified example 2 of the die pad shown in Figure 1. [Figure 4] This is a modified example 3 of the die pad shown in Figure 1. [Figure 5] This is a modified example 4 of the die pad shown in Figure 1. [Modes for carrying out the invention]

[0011] The lead frame of the present invention is a lead frame having a retaining portion at the lead end, characterized in that the retaining portion is further provided with an uneven portion consisting of a recess or a protrusion. In the present invention, it is preferable that the uneven portion is provided on all or part of the back surface of the retaining portion. According to this preferred range, the intrusion of flux, moisture, etc. can be prevented more efficiently. In the present invention, it is also preferable that the retaining portion and the uneven portion have a stepped shape of two or more steps. According to this preferred range, the intrusion of flux, moisture, etc. can be prevented more easily while maintaining good adhesion. In the present invention, it is preferable that the uneven portion is located within the sealing resin to more effectively prevent the intrusion of flux, moisture, etc. The lead is not particularly limited as long as it does not hinder the objective of the present invention, and any known lead may be used. For example, a recess that is inwardly recessed is formed at the end of the lead as the retaining portion, and the sealing resin enters this recess, thereby preventing the lead from falling out of the sealing resin.

[0012] In the present invention, the retaining portion is further provided with a concavo-convex portion formed by a concave portion or a convex portion. The concavo-convex portion is not particularly limited as long as it is formed by a concave portion or a convex portion, and may be a concavo-convex portion formed by a convex portion or a concavo-convex portion formed by a concave portion. Further, the concavo-convex portion does not have to have a regular shape, and may be, for example, a substantially polygonal shape such as a substantially triangular shape, a substantially quadrangular shape (e.g., a substantially square shape, a substantially rectangular shape or a substantially trapezoidal shape, etc.), a substantially pentagonal shape or a substantially hexagonal shape, a substantially circular shape, a substantially elliptical shape, etc. Further, the cross-sectional shape of the concave portion or the convex portion of the concavo-convex portion is not particularly limited, and examples thereof include a substantially U-shaped cross-sectional shape, a substantially U-shaped cross-sectional shape, a substantially inverted U-shaped cross-sectional shape, a substantially wave-shaped cross-sectional shape, the above-mentioned shape or a stepped shape, etc.

[0013] In the present invention, it is preferable that the concavo-convex portion is within the sealing resin. According to such a preferable range, the reliability of the semiconductor device can be more efficiently improved.

[0014] Examples of the sealing resin include thermosetting resins, and more specifically, epoxy resins, silicone resins, etc. are often used. When an epoxy resin is used, the sealing resin is formed by a transfer molding method or the like. When a thermoplastic resin is used as the sealing resin, the sealing resin is formed by an injection molding method or the like. A semiconductor element on which a semiconductor component is mounted is usually connected by a lead frame and bonding wires.

[0015] Note that metals such as gold, copper, and aluminum are used as the materials used for the bonding wires used in the present invention. As the bonding wire, for example, a gold wire, an aluminum wire, a copper wire, etc. are used. The temperature at the time of performing wire bonding may be within the range of 80 to 250°C or 80 to 220°C. The heating time may be several seconds to several minutes. Wire bonding may be performed by a combination of vibration energy by ultrasonic waves and pressure bonding energy by applied pressure while being heated within the above temperature range.

[0016] Note that metals such as copper alloys and iron alloys are used as the materials used for the lead frames used in the present invention.

[0017] In the present invention, it is preferable that the concavo-convex portion has a shape obtained by deforming a part of the lead within the sealing resin. According to such a preferable range, it is possible to more efficiently prevent the intrusion of flux, moisture, etc., and to make the adhesion between the lead and the sealing resin better.

[0018] In the present invention, it is preferable that the concavo-convex portion is a processed portion obtained by processing a part of the lead within the sealing resin. According to such a preferable range, it is possible to more efficiently prevent the intrusion of flux, moisture, etc., and to dramatically improve the reliability of the semiconductor device (especially an LED).

[0019] Hereinafter, preferred embodiments of the present invention will be described more specifically with reference to the drawings, but the present invention is not limited to these specific examples. In all of the preferred embodiments of the present invention shown below, the concavo-convex portion is provided on all or part of the back surface of the retaining portion, the retaining portion and the concavo-convex portion have a stepped shape of two or more steps, the concavo-convex portion is within the sealing resin, the concavo-convex portion has a shape obtained by deforming a part of the die pad within the sealing resin, and the concavo-convex portion is a processed portion obtained by processing a part of the die pad within the sealing resin.

[0020] Figure 1 is a schematic diagram showing a preferred lead configuration example of the present invention. The lead frame in Figure 1 includes a lead 1, a retaining portion 2, a recessed portion 3, a sealing resin 4, a die pad 5, a semiconductor chip 6, and a bonding wire 7. The retaining portion 2 and the recessed portion 3 are formed by crushing the lead 1 inside the sealing resin 4 in two or more stages. This configuration efficiently prevents the intrusion of flux and moisture. The processing means for the crushing process are not particularly limited as long as they do not hinder the objectives of the present invention and may be known processing means. The width and depth or height of the recesses or protrusions of the recessed portion 3 are not particularly limited as long as they do not hinder the objectives of the present invention, but in the present invention, the width is preferably 1 μm to 10 mm, and the depth or height is preferably 1 μm to 10 mm. According to these preferred ranges, better adhesion can be achieved, and the intrusion of flux and moisture can be prevented more efficiently.

[0021] Figure 2 shows Modification 1 of the lead shown in Figure 1. In Modification 1, the retaining portion 2 on the lead 1 is provided with a first uneven portion 3A and a second uneven portion 3B. This further improves the adhesion between the lead and the sealing resin, and more efficiently prevents the intrusion of flux and moisture. The width and depth or height of the recesses or protrusions of the uneven portion 3 are not particularly limited as long as they do not hinder the purpose of the present invention, but in the present invention, the width is preferably 1 μm to 10 mm, and the depth or height is preferably 1 μm to 10 mm. According to these preferred ranges, better adhesion can be achieved, and the intrusion of flux and moisture can be prevented more efficiently.

[0022] Figure 3 shows a modified example 2 of the lead shown in Figure 1. In modified example 2, the retaining portion 2 on the lead 1 is provided with recesses of the uneven portion 3, and the retaining portion is divided into a first retaining portion 2A and a second retaining portion 2B. This further increases the bonding area between the lead and the sealing resin, making it possible to more efficiently prevent the intrusion of flux and moisture. The width and depth or height of the recesses or protrusions of the uneven portion 3 are not particularly limited as long as they do not hinder the purpose of the present invention, but in the present invention, the width is preferably 1 μm to 10 mm, and the depth or height is preferably 1 μm to 10 mm. According to these preferred ranges, better adhesion can be achieved, and the intrusion of flux and moisture can be more efficiently prevented.

[0023] Figure 4 shows a modified example 3 of the lead shown in Figure 1. In modified example 3, the retaining portion 2 on the lead 1 is provided with a convex portion of the uneven portion 3, and the retaining portion is divided into a first retaining portion 2A and a second retaining portion 2B. This further increases the bonding area between the lead and the sealing resin, making it possible to more efficiently prevent the intrusion of flux and moisture. The width and depth or height of the concave or convex portion of the uneven portion 3 are not particularly limited as long as they do not hinder the purpose of the present invention, but in the present invention, the width is preferably 1 μm to 10 mm, and the depth or height is preferably 1 μm to 10 mm. According to these preferred ranges, better adhesion can be achieved, and the intrusion of flux and moisture can be more efficiently prevented.

[0024] Figure 5 shows a modified example 4 of the lead shown in Figure 1. In modified example 4, the retaining portion 2 on the lead 1 is provided with a protruding portion of the uneven portion 3. This further improves the adhesion between the lead and the sealing resin, and more efficiently prevents the intrusion of flux and moisture. The width and depth or height of the recesses or protrusions of the uneven portion 3 are not particularly limited as long as they do not hinder the purpose of the present invention, but in the present invention, the width is preferably 1 μm to 10 mm, and the depth or height is preferably 1 μm to 10 mm. According to these preferred ranges, better adhesion can be achieved, and the intrusion of flux and moisture can be prevented more efficiently.

[0025] (Example 1) A prototype lead frame with the lead shown in Figure 1 was fabricated, and its presence or absence of flux and moisture intrusion and improvement in reliability after packaging were evaluated. As a comparative example, a prototype lead frame with a lead that has a retaining portion formed as described in Patent Document 1 was fabricated, and its presence or absence of flux and moisture intrusion and improvement in reliability after packaging were similarly evaluated. As a result, the present invention product was able to significantly prevent the intrusion of flux and moisture, and an improvement in reliability was also observed. On the other hand, the comparative example product was unable to prevent the intrusion of flux and moisture, and no improvement in reliability was observed. [Industrial applicability]

[0026] The lead frame of the present invention is useful for semiconductor devices and the like. [Explanation of symbols]

[0027] 1 Lead 2. Retaining part 2A Retaining part 2B Retaining part 3 Uneven part 3A Uneven part 3B Uneven part 4 Sealing resin 5 Die Pads 6 Semiconductor chips 7 Bonding wire

Claims

1. A lead frame having a retaining portion at the lead end, wherein the retaining portion is further provided with a recessed or convex portion.

2. The lead frame according to claim 1, wherein the uneven portion is provided on all or part of the back surface of the retaining portion.

3. The lead frame according to claim 1, wherein the retaining portion and the uneven portion have a stepped shape of two or more steps.

4. The lead frame according to claim 1, wherein the aforementioned uneven portion is located within the sealing resin.

5. The lead frame according to claim 1, wherein the uneven portion is shaped by deforming a part of the lead within the sealing resin.

6. The lead frame according to claim 1, wherein the uneven portion is a processed portion obtained by processing a part of the lead within the sealing resin.

7. An electronic device including a lead frame, wherein the lead frame is the lead frame described in claim 1.

8. An electronic component including a lead frame, wherein the lead frame is the lead frame described in claim 1.

9. A product comprising a lead frame, wherein the lead frame is the lead frame described in claim 1.

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