CN108336054B

CN108336054B - Lead frame

Info

Publication number: CN108336054B
Application number: CN201810027005.1A
Authority: CN
Inventors: 石桥贵弘
Original assignee: Mitsui High Tec Inc
Current assignee: Mitsui High Tec Inc
Priority date: 2017-01-12
Filing date: 2018-01-11
Publication date: 2021-11-26
Anticipated expiration: 2038-01-11
Also published as: TWI706529B; CN108336054A; JP2018113433A; JP6856497B2; TW201832336A

Abstract

A lead frame includes a plurality of unit lead frames and a connection bar. The unit lead frames are arranged in a matrix, and each unit lead frame includes a chip pad and a plurality of leads. The connection bars connect the unit lead frames to each other. The unit lead frame has a die pad support portion for supporting the die pad to the tie bar, and the tie bar has a die pad connection portion connected to the die pad support portion and a body portion which is a region other than the die pad connection portion. The die pad supporting portion and the die pad connecting portion are thinner than the thickest region of the unit lead frame and thicker than the body portion.

Description

Lead frame

Technical Field

Embodiments of the present disclosure relate to a lead frame.

Background

Conventionally, in a lead frame of a MAP (Molded Array Package) type, a technique of performing half-etching processing on a back side of a predetermined region of a die pad, a lead, a tie bar, and the like is known (for example, see patent document 1).

Patent document 1 JP-A-2016-

Disclosure of Invention

However, in the conventional lead frame, for the deep etching in such a half etching process, the coupling portion between the die pad and the tie bar becomes thin to reduce the strength, and as a result, there is a fear that the die pad cannot be sufficiently supported to the tie bar. On the other hand, for the shallow etching in the half etching process, the tie bar becomes thick to improve the strength, and as a result, the warpage (warp) of the entire lead frame may increase. Further, in the case of manufacturing the MAP type semiconductor device, the risk of generating burrs by cutting along the tie bars becomes high.

One aspect of the embodiments has been completed based on the above, and a non-limiting object of the embodiments is to provide a lead frame capable of sufficiently supporting a die pad to a connection bar and also capable of reducing warpage of the entire lead frame.

A lead frame, comprising: a plurality of unit lead frames and connection bars. The unit lead frames are arranged in a matrix, and each unit lead frame includes a chip pad and a plurality of leads. The connection bars connect the unit lead frames to each other. The unit lead frame has a die pad support portion for supporting the die pad to the tie bar, and the tie bar has a die pad connection portion connected to the die pad support portion and a body portion which is a region other than the die pad connection portion. The die pad supporting portion and the die pad connecting portion are thinner than the thickest region of the unit lead frame and thicker than the body portion.

Aspects of the embodiment can provide a lead frame capable of appropriately supporting a die pad to a connection bar and reducing warpage of the entire lead frame.

Drawings

In the drawings:

fig. 1A is an overall view and an enlarged plan view of a lead frame according to an embodiment;

FIG. 1B is a cross-sectional view taken along line IB-IB shown in FIG. 1A;

fig. 2 is a schematic sectional view showing a step of manufacturing a lead frame according to the embodiment;

fig. 3A is an enlarged plan view of a lead frame according to a first modification of the embodiment;

FIG. 3B is a cross-sectional view taken along line IIIB-IIIB shown in FIG. 3A;

fig. 4A is an enlarged plan view of a lead frame according to a second modification of the embodiment;

FIG. 4B is a cross-sectional view taken along line IVB-IVB shown in FIG. 4A;

fig. 5A is an enlarged plan view of a lead frame according to a third modification of the embodiment; and

fig. 5B is a sectional view taken along line VB-VB in fig. 5A.

Reference numerals and labels corresponding to elements of embodiments of the present invention are listed below.

1. 1A, 1B, 1C: lead frame

10: frame body

11: unit lead frame

12: connecting rod

12 a: chip bonding pad connecting part

12 b: body part

12 c: stress relaxation part

12d, 12 e: reinforcing part

13. 13a to 13 e: chip bonding pad

14: lead wire

15: chip bonding pad supporting part

16: lead extension

20: metal plate

21a, 21 b: resist layer

22a, 22 b: glass mask

Detailed Description

< appearance and details of lead frame >

Embodiments of a lead frame disclosed in the present application will be described hereinafter with reference to the accompanying drawings. The present invention is not limited to the following examples.

First, the outer shape of the lead frame 1 according to the embodiment will be described with reference to fig. 1A. A lead frame 1 shown in fig. 1A is a MAP type lead frame used for manufacturing a SON (Small Outline Non-leaded package) type semiconductor device.

In addition, the embodiment shows the lead frame used for manufacturing the SON type semiconductor device, but may be applied to the lead frame used for manufacturing other types, for example, QFN (quad flat non-leaded package) type semiconductor devices.

The lead frame 1 has: a frame body 10, the frame body 10 having a rectangular shape in a plan view; and a plurality of unit lead frames 11, the plurality of unit lead frames 11 being arranged in a matrix state within such a frame body 10. A plurality of grid-shaped tie bars 12 are provided around the unit lead frame 11, and both ends of each tie bar 12 are supported by the frame 10.

The unit lead frame 11 has a die pad 13, a plurality of leads 14, and a die pad support bar 15. The die pad 13 has, for example, two die

pads

13a, 13b, and is disposed in the center of the unit lead frame 11. The front surface side of such a chip pad 13 can be equipped with a semiconductor chip (not shown).

A plurality of leads 14 are arranged between the die pad 13 and the tie bar 12, and an end 14a of each lead 14 extends from the tie bar 12 toward the die pad 13. Such a lead 14 is connected to an electrode of the semiconductor chip disposed on the die pad 13 by a bonding wire or the like, thereby serving as an external terminal of the semiconductor device.

The die pad support 15 joins the die pad 13 to the tie bar 12, and supports the die pad 13 to the tie bar 12. For example, one or more chip pad support parts 15 are formed on each of the two

chip pads

13a, 13 b.

The tie bar 12 has a die pad bonding portion 12a bonded to the die pad support portion 15 and a body portion 12b as a region other than the die pad bonding portion 12 a. In other words, the chip pad link portion 12a is a region that is arranged adjacent to the chip pad support portion 15 and directly supports the chip pad support portion 15.

For example, the lead frame 1 according to the embodiment is formed by etching a metal plate composed of, for example, copper, a copper alloy, or a nickel-iron alloy. Such etching includes: a full etching in which an opening is formed by etching both surfaces, and a half etching in which the metal plate is thinned by etching the rear surface side.

In addition, for ease of understanding, the enlarged plan view of the present specification will give some hatching to the half-etched regions, and will give the same hatching to the half-etched regions having the same thickness.

As shown in fig. 1A, in the embodiment, all the tie bars 12 are half-etched. Although the periphery of the chip pad 13 is half-etched, the center of the chip pad 13 is not half-etched and has a thickness equal to that of the metal plate before etching.

The periphery of the end 14a of the lead 14 is half-etched, and the portion other than the periphery is not half-etched. All the chip pad supports 15 are half-etched.

By half-etching a predetermined region of the lead frame 1 in this manner, the strength of the entire lead frame 1 can be made lower than in the case where half-etching is not performed. This can reduce the warpage of the lead frame 1. Further, the unevenness formed by half-etching improves adhesion to the sealing resin. This can improve the reliability of the semiconductor device.

Here, as shown in fig. 1B, the embodiment is configured such that: so that the thickness T1 of the die pad support part 15 and the thickness T2 of the die pad link part 12a in the tie bar 12 are both thicker than the thickness T3 of the body part 12b in the tie bar 12. In addition, fig. 1B shows the boundary lines of the respective regions by broken lines.

This can improve the strength of the die pad bonding portion 12a and the die pad supporting portion 15 for supporting the die pad 13. Therefore, this embodiment can sufficiently support the die pad 13 to the tie bar 12.

Also, the thickness T3 of the body portion 12b occupying most of the tie bar 12 can be made sufficiently thinner than the thickest region (for example, the center of the die pad 13 a) in the lead frame 1 where half etching is not performed. This can reduce the strength of the entire tie bar 12, thereby reducing the warpage of the entire lead frame 1.

That is, this embodiment can sufficiently support the die pad 13 to the tie bar 12 and reduce the warpage of the entire lead frame 1.

Further, by reducing the strength of the entire tie bar 12, the cutting resistance of the tie bar 12 can be reduced for cutting along the tie bar 12 in the case of manufacturing a MAP-type semiconductor device. Therefore, this embodiment can stably manufacture the semiconductor device.

In the above-described embodiment, when the thickness T4 of the region without half etching (i.e., the thickest region in the lead frame 1) is represented as 100%, the thickness T1 of the chip-pad support portion 15 and the thickness T2 of the chip-pad link portion 12a are preferably 40% to 60% of the thickness T4, and the thickness T3 of the body portion 12b is preferably 30% to 50% of the thickness T4. That is, the following expression is preferably satisfied:

T4*0.4≤T1≤T4*0.6；

t4 x 0.4 is not less than T2 is not less than T4 x 0.6; and

T4*0.3≤T3≤T4*0.5。

when the thickness T1 or T2 is made thicker than 40% to 60% of the thickness T4, the strength of the lead frame 1 is increased, which tends to warp the lead frame 1. Also, when the thickness T1 or T2 is made thinner than 40% to 60% of the thickness T4, the lead frame 1 may be deformed.

Similarly, when the thickness T3 is made thicker than 30% to 50% of the thickness T4, the strength of the lead frame 1 is increased, which tends to warp the lead frame 1. Also, when the thickness T3 is made thinner than 30% to 50% of the thickness T4, the lead frame 1 may be deformed.

In addition, in the embodiment, when the thickness T4 of the region without half etching is expressed as 100%, it is preferable to make the thickness T1 of the chip-pad supporting portion 15 and the thickness T2 of the chip-pad linking portion 12a thicker than the thickness T3 of the body portion 12b by 5% or more. This can ensure compatibility between sufficient support of the chip pad 13 and reduction of warpage of the entire lead frame 1 well. The following expression can be obtained:

t1 is more than or equal to T3+ T4 x 0.05; and

T2≥T3+T4*0.05。

in addition, when the difference between the thickness T3 and the thickness T1 or T2 is less than 5%, the improvement in strength for preventing deformation of the lead frame 1 and the reduction in strength for preventing warpage of the lead frame 1 are contradictory. This may cause the lead frame 1 to be deformed or warped.

In addition, in the embodiment, it is preferable that the thickness T1 of the die pad support part 15 be equal to the thickness T2 of the die pad link part 12 a. This enables the chip pad support portion 15 and the chip pad bonding portion 12a to be processed under the same etching conditions in the step of manufacturing the lead frame 1 described below. This can suppress complication of the etching conditions, thereby improving the productivity of the lead frame 1.

Further, in the embodiment, it is preferable that the thickness T3 of the body portion 12b is made equal to the thickness T5 of the peripheral edge of the chip pad 13. As above, this can suppress complication of the etching conditions, thereby improving the productivity of the lead frame 1.

Also, as shown in fig. 1A, the left side surface of the die pad 13b is supported to the tie bar 12 via one lead 14 and a lead extension 16, and the lead extension 16 extends from such lead 14 toward the die pad 13b and is bonded to the die pad 13 b.

Therefore, in the tie bar 12 of the embodiment, the region joined to the lead 14 formed with the lead extension 16 is also preferably configured as the die pad joint portion 12 a. This can sufficiently support the die pad 13b to the tie bar 12.

Also, this embodiment is particularly effective in the lead frame 1 having a complicated design and a different shape, for example, the chip pad 13 is divided into two

chip pads

13a, 13b, as shown in fig. 1A. This is because such a lead frame 1 having a different shape requires the die pad support portion 15 having a sufficient support function because there is a limit to the arrangement and number of the die pad support portions 15, as compared with a lead frame not having a different shape.

< method for manufacturing lead frame >

Subsequently, a method of manufacturing the lead frame 1 according to the embodiment will be described with reference to fig. 2. In addition, the cross section shown in fig. 2 corresponds to a cross sectional view taken along the line IB-IB shown in fig. 1A (i.e., fig. 1B).

First, resist

layers

21a, 21b such as dry film resists are attached to the front and rear surfaces of a metal plate 20 as a material of the lead frame 1 shown in fig. 2(a) (fig. 2 (b)).

Next, exposure and development are performed using

glass masks

22a, 22b formed in the shape of the lead frame 1 (fig. 2(c)), and a resist mask covered with the resist

layers

21a, 21b is formed in a predetermined range.

Here, as shown in fig. 2(d), a region a1 where the metal plate 20 is not etched is formed with a resist mask, so that the resist

layers

21a, 21b are formed on both surfaces. In the region a2 where the metal plate 20 is subjected to the deep half etching, a resist mask is formed, and only the front surface is formed with the resist layer 21 a.

Further, in this embodiment, the region a3 of the metal plate 20 subjected to the shallow half etching is formed with a resist mask so that the front surface is uniformly formed with the resist layer 21a, and the rear surface is formed with the resist layer 21b in a predetermined pattern (e.g., a dot pattern).

Then, the metal plate 20 is etched using, for example, an iron chloride solution (fig. 2 (e)). In this case, as shown in fig. 2(e), in the region a2, no resist mask is formed on the back surface side, and as a result, etching is performed in the depth direction.

In contrast, in the region A3, the resist layer 21b having a predetermined pattern is formed, and as a result, although etching is not performed in the depth direction as compared with the region a2, etching is performed on the rear side of the pattern of the resist layer 21 b.

Then, when this back side etching is performed, the entire back side of the pattern of the resist layer 21b is etched. This peels off the resist layer 21b formed in the region a 3. Then, after such peeling, etching is uniformly performed in the depth direction in the region a2 and the region A3.

However, in the region a2 and the region A3, in the first stage of etching, a difference in the etching amount in the depth direction is caused. This causes a difference in the etching amount in the depth direction in the region a2 and the region A3 as shown in fig. 2F.

Finally, cleaning and peeling of the resist mask are performed to complete the lead frame 1 according to the embodiment (fig. 2 (g)). Here, as shown in fig. 2(g), the area a1 corresponds to the center of the chip pad 13a that is not etched, and the area a2 corresponds to the body portion 12b of the tie bar 12 and the periphery of the chip pad 13a, and the area A3 corresponds to the chip pad support portion 15 and the chip pad bonding portion 12a of the tie bar 12.

That is, as described above, by forming the back surface side resist layer 21b with a predetermined pattern, it is possible to make a difference in etching amount in the depth direction. This enables the formation of regions having different half-etching depths in the lead frame 1.

In addition, the region of the lead frame 1 where the opening is intended to be provided is preferably formed with a resist mask so that both surfaces of the metal plate 20 are not formed with the resist

layers

21a, 21b (not shown in fig. 2).

< modification >

Subsequently, various modifications of the lead frame 1 according to the embodiment will be described. Fig. 3A is an enlarged plan view of a lead frame 1A according to a first modification of the embodiment, and is a view corresponding to a lower view of fig. 1A in the embodiment.

Like the above-described embodiment, in the lead frame 1A according to the first modification, the die pad support portion 15 and the die pad bonding portion 12a of the tie bar 12 are thicker than the body portion 12b of the tie bar 12. On the other hand, unlike the above embodiment, the tie rod 12 further has a stress relaxing portion 12 c.

Such stress relaxation portions 12c are formed in regions capable of further reducing the warpage of the lead frame 1A by relaxing the stress in the tie bars 12, and are formed at, for example, intersections of the tie bars 12 extending in the longitudinal and lateral directions, as shown in fig. 3A.

As shown in fig. 3B, the stress relaxing section 12c is formed to have a thickness T6 smaller than the thickness T3 of the body section 12B of the coupler shaft 12. This can further relax the stress of the entire tie bar 12, thereby further reducing the warpage of the entire lead frame 1A.

In the first modification, when the thickness T4 of the region without half etching is expressed as 100%, the thickness T6 of the stress relaxation portion 12c is preferably 20% to 40% of the thickness T4 so as to satisfy the following expression:

T4*0.2≤T6≤T4*0.4。

also, in the first modification, when the thickness T4 of the region where half etching is not present is expressed as 100%, it is preferable that the thickness T6 of the stress relaxation portion 12c be thinner than the thickness T3 of the body portion 12b by 5% or more. This can further reduce the warpage of the entire lead frame 1A. That is, the following expression is preferably satisfied:

T6≤T3-T4*0.05。

further, as shown in fig. 3B, in order to perform half etching from the thickness T4 of the non-etched region to the thicknesses T2, T3, and T6 of three levels, the etching conditions are set to the region of the thickness T6 requiring the deepest etching, and the regions of the thicknesses T2 and T3 are simply formed with resist layers 21B having patterns of different shapes, respectively.

By forming the resist layer 21b having patterns of different shapes in this manner and etching the resist layer 21b, it is possible to make the peeling of the resist layer 21b from the rear surface of the metal plate 20 have a time difference (see fig. 2 (e)). This enables different etch depths of the respective regions.

In addition, in the lead frame 1A according to the first modification, the stress relaxing portion 12c is formed at the intersection of the tie bars 12 extending in the longitudinal and lateral directions, but may be formed in a region of the tie bars 12 other than the intersection.

Fig. 4A is an enlarged plan view of a lead frame 1B according to a second modification of the embodiment. The lead frame 1B according to the second modification is different from the embodiment and the first modification in the configuration of the unit lead frames 11. The die pad 13 constituting the unit lead frame 11 of the second modification has three

die pads

13c, 13d, 13e, and such three die

pads

13c, 13d, 13e are formed in the center of the unit lead frame 11.

Also, one or more chip-pad supports 15 for bonding the chip pads 13 to the tie bars 12 are formed on each of the three

chip pads

13c, 13d, 13e (in the second modification, two are formed on each of the

chip pads

13c, 13e, and four are formed on the chip pad 13 d).

Here, in the unit lead frame 11 of the second modification, the

die pads

13c, 13e are not bonded to the die pad 13D, and as a result, the lead frame 1B has a low-strength region arranged on a straight line D shown by a two-dot chain line. This may deform the lead frame 1B along such a straight line D.

Here, in the second modification, a low-strength region arranged on the straight line D in the connection bar 12 within the lead frame 1B is provided with a reinforcement portion 12D. The thickness T7 of the reinforcing portion 12d is larger than the thickness T2 of the die pad bonding portion 12a of the tie bar 12, as shown in fig. 4B.

This can improve the strength of the region arranged on the straight line D within the lead frame 1B. Therefore, the second modification can prevent the lead frame 1B from being deformed.

Also, in the second modification, it is preferable to make the thickness T7 of the reinforcing portion 12d equal to the thickness of the thickest region not half-etched in the lead frame 1B (for example, the center of the die pad 13 c). This can further improve the strength of the region arranged on the straight line D within the lead frame 1B, thereby further preventing the lead frame 1B from being deformed.

In addition, the second modification shows an example in which the reinforcing portion 12D is provided only to a low-strength region arranged on a straight line D within the lead frame 1B, but a region adjacent to a region arranged on such a straight line D may also be provided with the reinforcing portion 12D. This can further improve the strength of the region arranged on the straight line D within the lead frame 1B, thereby further preventing the lead frame 1B from being deformed.

Also, the second modification shows an example in which the low-strength region arranged in the lateral direction is reinforced with the reinforcement portion 12d, but the low-strength region arranged in the longitudinal direction may be reinforced with the reinforcement portion 12 d.

Fig. 5A is an enlarged plan view of a lead frame 1C according to a third modification of the embodiment. The lead frame 1C according to the third modification is the same as that of the second modification in the configuration of the die pad 13. That is, the chip pad 13 constituting the unit lead frame 11 of the third modification has three

chip pads

13c, 13d, 13e, and such three

chip pads

13c, 13d, 13e are formed in the center of the unit lead frame 11.

chip pads

13c, 13d, 13e (in the third modification, two are formed on each of the

chip pads

13c, 13e, and four are formed on the chip pad 13 d).

On the other hand, the third modification is different from the embodiment, the first modification, and the second modification in the configuration of the connection bar 12 and the die pad support portion 15. Specifically, the tie bar 12 is constituted by the body portion 12b, and the chip-pad support portion 15 is equal in thickness to the body portion 12 b. That is, in the third modification, the thicknesses of all the half-etched regions in the lead frame 1C are substantially equal.

Here, like the second modification, in the unit lead frame 11 of the third modification, the die pads 13C, 13e are not joined to the die pad 13D, and as a result, the lead frame 1C has a low-strength region arranged on the straight line D shown by the two-dot chain line. This may deform the lead frame 1C along such a straight line D.

Therefore, in the third modification, a low-strength region in the straight line D arranged in the connection bar 12 within the lead frame 1C is provided with the reinforcement portion 12D. The thickness T7 of the reinforcing portion 12d is thicker than the thickness T3 of the main body portion 12B of the coupler shaft 12, as shown in fig. 5B.

This can improve the strength of the region arranged on the straight line D within the lead frame 1C. Therefore, the third modification can prevent the lead frame 1C from being deformed.

Also, in the third modification, a region adjacent to the region disposed on the straight line D is preferably provided with the reinforcement portion 12 e. That is, each reinforcing portion 12e adjacent to the reinforcing portion 12d is preferably formed to have a thickness T8 thicker than a thickness T3 of the body portion 12B in the tie bar 12, as shown in fig. 5B.

This can further improve the strength of the region arranged on the straight line D within the lead frame 1C, thereby further preventing the lead frame 1C from being deformed.

Further, in the third modification, it is preferable to make the thickness T7 of the reinforcement portion 12d and the thickness T8 of the reinforcement portion 12e equal to the thickness of the thickest region not subjected to half etching (for example, the center of the die pad 13C) in the lead frame 1C.

In addition, the third modification shows an example in which the reinforcement portion 12e is added to the reinforcement portion 12D, but the strength of the region disposed on the straight line D may be improved with only the reinforcement portion 12D. Also, the third modification shows an example in which the low-strength region arranged in the lateral direction is reinforced with the reinforcing

portions

12d, 12e, but the low-strength region arranged in the longitudinal direction may be reinforced with the reinforcing

portions

12d, 12 e.

The embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the half-etched region is formed in a thickness of two or three levels, but may be formed in a thickness of four or more levels. This can better ensure compatibility between sufficient support of the chip pad 13 and reduction of warpage of the entire lead frame 1.

As described above, the lead frame 1(1A, 1B) according to the embodiment includes the plurality of unit lead frames 11 and the connection bars 12. The unit lead frames 11 are arranged in a matrix, and each unit lead frame 11 has a chip pad 13 and a plurality of leads 14. The connection bars 12 connect the unit lead frames 11 to each other. Also, the unit lead frame 11 has a die pad support portion 15 for supporting the die pad 13 to the tie bar 12, and the tie bar 12 has a die pad connection portion 12a connected to the die pad support portion 15 and a body portion 12b as a region other than the die pad connection portion 12 a. The die pad support portion 15 and the die pad connection portion 12a are thinner than the thickest region of the unit lead frame 11 and thicker than the body portion 12 b. This can sufficiently support the die pad 13 to the tie bar 12 and reduce warpage of the entire lead frame 1(1A, 1B).

Also, in the lead frame 1(1A, 1B) according to the embodiment, when the thickness T4 of the thickest region in the unit lead frame 11 is expressed as 100%, the thickness T1 of the chip-pad support portion 15 and the thickness T2 of the chip-pad bonding portion 12a are thicker than the thickness T3 of the body portion 12B by 5% or more, so as to satisfy the following expression: t1 is more than or equal to T3+ T4 x 0.05; and T2 is more than or equal to T3+ T4 x 0.05. This can ensure compatibility between sufficient support of the chip pad 13 and reduction of warpage of the entire lead frame 1(1A, 1B) well.

Also, in the lead frame 1(1A, 1B) according to the embodiment, at least one unit lead frame 11 has a plurality of die pads 13 (die pads 13a to 13 e). This enables the chip pad 13 to be sufficiently supported in the lead frames 1(1A, 1B) having different shapes.

Also, in the lead frame 1(1A, 1B) according to the embodiment, the thickness of the die pad support portion 15 is equal to the thickness of the die pad bonding portion 12 a. This can improve the productivity of the lead frame 1(1A, 1B).

Also, in the lead frame 1A according to the embodiment, the tie bar 12 further has the stress relaxing portion 12c thinner than the body portion 12 b. This can further reduce the warpage of the entire lead frame 1A.

Also, in the lead frame 1A according to the embodiment, when the thickness T4 of the thickest region in the unit lead frame 11 is expressed as 100%, the thickness T6 of the stress relaxing portion 12c is thinner than the thickness T3 of the body portion 12b by 5% or more to satisfy the following expression: t6 is less than or equal to T3-T4 x 0.05. This can further reduce the warpage of the entire lead frame 1A.

Also, in the lead frame 1B according to the embodiment, the tie bar 12 also has the reinforcing portion 12D thicker than the die pad bonding portion 12a in the low-strength region arranged on the straight line D within the lead frame 1B. This can prevent the lead frame 1B from being deformed.

Also, in the lead frame 1B according to the embodiment, the thickness of the reinforcing portion 12d is equal to the thickness of the thickest region in the unit lead frame 11. This can further prevent the lead frame 1B from being deformed.

Further effects and modifications can be easily obtained by those skilled in the art. As a result, the broader aspects of the invention are not limited to the specific details and illustrative examples described above. Accordingly, various modifications may be made without departing from the spirit or scope of the overall invention as defined by the appended claims and the equivalents of the claims.

Claims

1. A lead frame, comprising:

a plurality of unit lead frames arranged in a matrix, each of the unit lead frames having a chip pad and a plurality of leads; and

a connection bar for connecting the plurality of unit lead frames to each other, wherein,

each of the plurality of unit lead frames has a die pad support portion for supporting the die pad to the tie bar,

the tie bar has a die pad link portion coupled to the die pad support portion and a body portion which is an area other than the die pad link portion and which

The die pad supporting part and the die pad connecting part are thinner than the thickest region of the unit lead frame and thicker than the body part.

2. The lead frame according to claim 1, wherein, when a thickness T4 of a thickest region in the unit lead frame is represented as 100%, a thickness T1 of the chip-pad support portion and a thickness T2 of the chip-pad link portion are thicker than a thickness T3 of the body portion by 5% or more, so as to satisfy the following expression:

t1 is more than or equal to T3+ T4 x 0.05; and

T2≥T3+T4*0.05。

3. the lead frame according to claim 1 or 2, wherein at least one of the plurality of unit lead frames includes a plurality of chip pads.

4. The lead frame according to claim 1 or 2, wherein a thickness of the die pad support is equal to a thickness of the die pad link.

5. The lead frame according to claim 1 or 2, wherein the connection bar further includes a stress relaxing portion thinner than the body portion.

6. The lead frame according to claim 5, wherein, when a thickness T4 of a thickest region in the unit lead frame is represented as 100%, a thickness T6 of the stress relaxing portion is thinner than a thickness T3 of the body portion by 5% or more to satisfy the following expression:

T6≤T3-T4*0.05。

7. the lead frame according to claim 1 or 2, wherein the connection bar further includes a reinforcement portion thicker than the die pad link portion in a low-strength region arranged in a straight line in the lead frame.

8. The lead frame according to claim 7, wherein the thickness of the reinforcement part is equal to that of the thickest region in the unit lead frame.