Lead frame and lead frame sheet

Abstract

The present invention relates to a lead frame material sheet comprising a plurality of lead frames, each of which comprises a substrate and a plurality of step structures. The substrate comprises a first surface, a second surface, and a plurality of side surfaces. On at least one of the side surfaces, a flattened area and a tearing area are sequentially formed from the first surface toward the second surface. The plurality of step structures are arranged along the extending direction of the intersection line between the second surface and the side surface, and each step structure comprises a convex portion and a concave portion. The maximum distance between the convex portion and the concave portion along the perpendicular direction of the side surface forms a step difference, which allows metal wires to easily break and detach from each step structure during the punching and shearing process, thereby effectively suppressing the formation of metal wires.

Description

Technical Field

[0001] The present invention relates to a lead frame related product, in particular to a lead frame and a lead frame sheet capable of suppressing metal wires. Background Art

[0002] In the manufacturing of conventional lead frame sheets, unnecessary materials may be removed from a metal sheet by etching or stamping to form a lead frame sheet with a specific shape and structure.

[0003] Among them, stamping is to install a metal sheet in a mold, and remove material by relative movement of the upper and lower parts of the mold. The cross-sectional edges punched out on the metal sheet are easily torn to form irregular burrs.

[0004] After stamping, metal sheets made of some metal materials are prone to partial peeling from the burrs to form thin and long metal wires. If the length of the metal wires is too long, the metal wires are likely to connect with other parts of the lead frame or other electronic components after the lead frames (units) of the existing lead frame sheets undergo the packaging process, causing short circuit problems in the end product. In summary, the presence of metal wires in the existing lead frame sheets after stamping can easily cause electrical problems and short circuits in the end product, resulting in poor end product yield and other problems. There is indeed room for improvement. Summary of the Invention

[0005] To address the problems of conventional lead frame materials, which are prone to electrical issues and short circuits in end products after stamping, and which result in poor end product yield, the present invention provides a lead frame and lead frame material capable of suppressing metal wires, thereby improving the problems of conventional lead frame materials, as further described below.

[0006] The present invention provides a lead frame, which includes:

[0007] A substrate comprising a first surface, a second surface opposite to the first surface, and a plurality of side surfaces intersecting the first surface and the second surface, wherein a flat region and a tear region are sequentially formed on at least one of the side surfaces from the first surface toward the second surface; and

[0008] a plurality of step structures located on the second surface and adjacent to the tear zone, the plurality of step structures being arranged along an extension direction of an edge line intersecting the second surface and the at least one side surface, and each step structure including a convex portion and a concave portion, wherein a maximum distance between the convex portion and the concave portion along a direction perpendicular to the at least one side surface forms a step;

[0009] The plurality of step structures are adjacently arranged, and a distance between the convex portions of two adjacent step structures or a distance between the concave portions of two adjacent step structures forms a pitch, wherein the pitch is less than or equal to 0.2 mm.

[0010] The present invention also provides a lead frame material sheet, which includes:

[0011] two tracks, the two tracks being arranged in parallel; and

[0012] A plurality of the above-mentioned lead frames are arranged between the two tracks.

[0013] By utilizing the above-mentioned technical features, the present invention provides the plurality of step structures on each lead frame of the lead frame material. By utilizing the principle of mechanics, the metal wires are easily broken and detached from each step structure during the punching and shearing process. This effectively suppresses the generation of metal wires and solves the problems of defective end products, short circuits, and failures caused by metal wires. In summary, the present invention effectively improves the problems of existing lead frames, thereby providing a lead frame and lead frame material that can suppress metal wires. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a partially enlarged three-dimensional schematic diagram of the appearance of the first preferred embodiment of the present invention.

[0015] Figure 2 It is a partially enlarged top view of the first preferred embodiment of the present invention.

[0016] Figure 3 yes Figure 1 Magnified view of circled area A.

[0017] Figure 4 yes Figure 2 Magnified view of the area circled in B.

[0018] Figure 5 yes Figure 4 Magnified view of circle C.

[0019] Figure 6 yes Figure 5 Schematic side view of the DD cutting line.

[0020] Figure 7 It is a partially enlarged three-dimensional schematic diagram of the appearance of the second preferred embodiment of the present invention.

[0021] Figures 8 to 10 The figures are scanning electron microscope (SEM) images of the second preferred embodiment of the present invention at different magnifications.

[0022] Figure 11It is a partially enlarged three-dimensional schematic diagram of the appearance of the third preferred embodiment of the present invention.

[0023] Figures 12 to 14 : is a SEM image of the third preferred embodiment of the present invention, wherein: Figures 12 to 14 These are SEM images of three types of samples having a platform area according to the present invention. DETAILED DESCRIPTION

[0024] In order to understand the technical features and practical effects of the present invention in detail and to implement them according to the contents of the specification, the preferred embodiments shown in the accompanying drawings are further described in detail as follows:

[0025] The first preferred embodiment of the present invention is Figure 1 and Figure 2 As shown, the lead frame material sheet 1 includes two tracks 2 and a plurality of lead frames 10. The plurality of lead frames 10 are arranged between the two tracks 2 at intervals, and the arrangement is not limited to Figure 1 and Figure 2 The structural aspect shown.

[0026] Further, if Figures 2 to 5 As shown, each of the lead frames 10 includes a substrate 11 and a plurality of step structures 20, wherein the substrate 11 has a first surface 111, a second surface 112 and a plurality of side surfaces 113, wherein the first surface 111 and the second surface 112 are two opposite surfaces of the substrate 11, respectively. In the first preferred embodiment of the present invention, the first surface 111 corresponds to a punch of a stamping die, and the second surface 112 corresponds to the substrate of the stamping die; the plurality of side surfaces 113 are formed between the first surface 111 and the second surface 112, and intersect with the first surface 111 and the second surface 112, wherein, as shown in FIG. Figure 3 As shown, after the lead frame material 1 is stamped, a flat region 31 and a tear region 32 are sequentially formed on at least one side surface 113 thereof from the first surface 111 toward the second surface 112 .

[0027] Secondly, if Figure 2 As shown, the substrate 11 of each lead frame 10 includes a main body area 110, a plurality of pins 12 and an inner pin area 13, wherein the inner pin area 13 is located between the main body area 110 and the plurality of pins 12, and provides power connection between the main body area 110 and the plurality of pins 12; it should be particularly noted that the extension range of the first surface 111 and the second surface 112 both covers the main body area 110, the plurality of pins 12 and the inner pin area 13, and each of the side surfaces 113 is correspondingly located on one of the main body area 110, the plurality of pins 12 and the inner pin area 13, and is formed between the first surface 111 and the second surface 112.

[0028] Furthermore, it can be seen from the above description that the side surface 113 where the flattened area 31 and the tearing area 32 are formed can be located in the main body area 110 , one of the pins 12 or the inner pin area 13 .

[0029] Please refer to Figures 3 to 6 As shown, the plurality of step structures 20 are located on the second surface 112 of the substrate 11 and adjacent to the tearing zone 32 of the at least one side surface 113. The plurality of step structures 20 are arranged along the extension direction D1 of the intersection line between the second surface 112 and the at least one side surface 113, and each of the step structures 20 includes a convex portion 21 and a concave portion 22. Figure 5 As shown, the maximum distance between the protrusion 21 and the recess 22 along the vertical direction D2 of the at least one side surface 113 forms a step difference d. Due to the formation of the step difference d, a breakpoint can be formed near the protrusion 21, allowing the material peeled off from the tear zone 32 to form a metal wire to break at the breakpoint, thereby producing the effect of suppressing the metal wire.

[0030] If the step difference d is too small, the mechanical fracture effect generated by the multiple step difference structures 20 will be weak, which may make the material of the metal wire less likely to break at the breakpoint. Therefore, in a preferred case, the step difference d is greater than or equal to 0.005 mm. In addition, the step difference d can be controlled to a size less than or equal to 0.1 mm to avoid the problem that each step difference structure 20 is too large and forms larger burrs and stamping powder is easily attached to the surface of the lead frame 10, resulting in poor performance or failure of the packaged product. In the first preferred embodiment of the present invention, the step difference d is preferably between 0.01 and 0.04 mm.

[0031] Further, with respect to the first preferred embodiment of the present invention, if Figure 3 and Figure 5 As shown, the multiple step structures 20 are arranged adjacent to each other, and the distance between the protrusions 21 of two adjacent step structures 20 or the distance between the concave portions 22 of two adjacent step structures 20 forms a pitch p. Preferably, the pitch p is less than or equal to 0.2 mm. If the pitch p exceeds 0.2 mm, unexpected metal wires may appear; wherein, "the distance between two adjacent protrusions 21" and "the distance between two adjacent concave portions 22" refer to the distance between the relative convex points in the two protrusions 21 or the relative concave points in the two concave portions 22.

[0032] Among them, if the pitch p is too small, the processing difficulty of the punching and shearing device corresponding to the lead frame material sheet 1 is high, so the pitch p can be set to be greater than or equal to 0.03 mm. In the first preferred embodiment of the present invention, the pitch p is between 0.05 and 0.1 mm. Furthermore, in order to achieve the same effect of suppressing the metal wire, the numerical changes of the pitch p and the step difference d will affect each other. Therefore, the multiple step difference structures 20 can be designed by the ratio of the pitch p to the step difference d. In the first preferred embodiment of the present invention, the ratio (p / d) is between 4 and 20.

[0033] Furthermore, in a first preferred embodiment of the present invention, if Figure 5 As shown, the multiple step structures 20 are arranged at equal pitches, and the concave portion 22 of each step structure 20 is in an arc shape, the convex portion 21 of the step structure 20 is formed at the end of the arc, and the step d is formed between the convex portion 21 and the midpoint of the arc, and the multiple step structures 20 are arranged adjacent to each other, so that each convex portion 21 forms a sharp point, thereby achieving a better effect of suppressing the metal wire due to stress concentration near the convex portion 21; despite this, in the case where the convex portion 21 is not sharp, since a breakpoint can be formed near the convex portion 21, the material peeled off from the tear zone 32 can be broken at the breakpoint position, so the effect of suppressing the metal wire can still be achieved.

[0034] Please refer to Figure 6 As shown, under the premise of not affecting the terminal product, after the stamping process, the lead frame 10 can also form a protrusion 114 on the second surface 112 of the substrate 11 near the tearing area 32. The protrusion 114 protruding from the second surface 112 is defined by a height t, and the maximum distance of the protrusion 114 protruding from the second surface 112 along the vertical direction D2 of the at least one side surface 113 is defined by a horizontal length s. Preferably, the height t of the protrusion 114 does not exceed 0.05 mm, and the horizontal length s does not exceed 0.15 mm. In addition, it should be noted that Figure 6 This is a schematic diagram. In an actual lead frame 10 , the surface of the protrusion 114 that is relatively far away from the second surface 112 may be flat or non-flat.

[0035] In addition to the situation where the multiple step structures 20 are arranged adjacent to each other, if the multiple step structures 20 are arranged at intervals, the distance between any two adjacent step structures 20 is less than or equal to 0.05 mm, so as to achieve an effect of suppressing metal wires similar to the above-mentioned pitch p value range.

[0036] Please refer to Figures 11 to 14As shown, in other possible embodiments, the substrate 11 may have a platform region 103 formed between the plurality of step structures 20 and the tear zone 32 of the side surface 113. The platform region 103 is generally parallel to the second surface 112, and the surface of the platform region 103 may be flat or slightly uneven. In the embodiment with the platform region 103, the range of the protrusion 114 falls within the range of the plurality of step structures 20 and the platform region 103.

[0037] Regarding the second preferred embodiment of the present invention, please refer to Figures 7 to 10 As shown, the difference from the first preferred embodiment is that: the substrate 11 includes a base layer 101 and a coating 102 provided on the second surface 112 of the substrate 11, wherein the base layer 101 and the coating 102 are different metal materials, for example, the base layer 101 can be copper, the coating 102 can be nickel, etc., and in the second preferred embodiment of the present invention, the multiple step structures 20 are simultaneously formed on the base layer 101 and the coating 102, that is, the base layer 101 and the coating 102 simultaneously have the convex portion 21 and the concave portion 22 of the step structure 20, so as to prevent the base layer 101 or the coating 102 from generating metal wires near the tearing area 32 and causing short circuit problems in the terminal product.

[0038] Please refer to Figures 11 to 14 As shown, the difference between the third preferred embodiment of the present invention and the second preferred embodiment is that the multiple step structures 20 are formed on the coating 102, and the coating 102 is in an inward position relative to the surface of the tearing zone 32, that is, the base layer 101 is exposed to form a platform area 103, and the platform area 103 is formed between the multiple step structures 20 and the tearing zone 32, wherein, Figures 12 to 14 The SEM images of three types of the third preferred embodiment of the present invention are as follows: Figure 13 In the embodiment shown, the edge of the coating 102 is flattened to form the plurality of step structures 20; on the other hand, Figure 14 In the embodiment shown, the base layer 101 forms a raised portion of the protrusion 114 near the edge of the plurality of step structures 20 on the coating layer 102. Figure 14 In the figure, relative to the surface of the tearing area 32 , from the outside to the inside of the lead frame 10 , the platform area 103 , the raised portion of the protrusion 114 , and the step structure 20 can be observed in sequence.

[0039] Furthermore, when the lead frame 10 provided by the present invention is magnified and observed, Figure 7 and Figure 10As shown, the plurality of step structures 20 can be observed to have an outer wave line 201 and an inner wave line 202 (the outer wave line 201 and the inner wave line 202 may partially overlap). At this time, if the step d is interpreted as the distance from the convex point of the outer wave line 201 to the concave point of the inner wave line 202 (i.e., the maximum distance between the convex portion 21 and the concave portion 22 along the vertical direction D2 of the at least one side surface 113), then the step d is between 0.02 and 0.1 mm. When the step structure 20 of the lead frame 10 is, as in the first preferred embodiment, Figure 3 , presented or observed as a wave line, the range of the step difference d is between 0.005 and 0.05 mm, preferably between 0.01 and 0.04 mm.

[0040] By virtue of the above-mentioned technical features, the present invention provides the plurality of step structures 20 on each of the lead frames 10 of the lead frame material 1, thereby allowing the metal wires to easily break and detach from each of the step structures 20 during the stamping process through the principle of mechanics. This effectively suppresses the metal wires, achieving a wire-free effect, and solving the problem of defective end products, short circuits, or failures caused by metal wires. In addition, by means of the step difference d values ​​and pitch p values ​​of the plurality of step structures 20, the size range of the metal wires that may be generated can be further controlled according to needs, thereby improving the reliability of each of the lead frames 10. In summary, the present invention effectively improves the problems of existing lead frames, thereby providing a lead frame 10 and a lead frame material 1 that can suppress metal wires.

[0041] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any person with ordinary knowledge in the technical field can make equivalent embodiments by making partial changes or modifications to the technical content disclosed in the present invention without departing from the scope of the technical solution of the present invention, and the equivalent embodiments still fall within the scope of the technical solution of the present invention without departing from the technical solution of the present invention.

Claims

1. A lead frame, characterized in that: Includes: A substrate comprising a first surface, a second surface opposite to the first surface, and a plurality of side surfaces intersecting the first surface and the second surface, wherein a flat region and a tear region are sequentially formed on at least one of the side surfaces from the first surface toward the second surface; as well as a plurality of step structures located on the second surface and adjacent to the tear zone, the plurality of step structures being arranged along an extension direction of an edge line intersecting the second surface and the at least one side surface, and each step structure including a convex portion and a concave portion, wherein a maximum distance between the convex portion and the concave portion along a direction perpendicular to the at least one side surface forms a step; The plurality of step structures are adjacently arranged, and a distance between the convex portions of two adjacent step structures or a distance between the concave portions of two adjacent step structures forms a pitch, wherein the pitch is less than or equal to 0.2 mm.

2. The lead frame according to claim 1, wherein: The plurality of step structures are arranged at equal pitches.

3. The lead frame according to claim 1, wherein: The concave portion of each step-difference structure is in an arc shape, the convex portion is formed at the end of the arc, and the step is formed between the end and the midpoint of the arc, and each convex portion forms a sharp point.

4. The lead frame according to claim 1, wherein: The pitch is greater than or equal to 0.03 mm.

5. The lead frame according to claim 1, wherein: The pitch is between 0.05 and 0.1 mm.

6. The lead frame according to claim 1, wherein: The ratio of the pitch to the step difference is between 4 and 20.

7. The lead frame according to any one of claims 1 to 5, wherein: The step difference is greater than or equal to 0.005 mm.

8. The lead frame according to claim 7, wherein: The step difference is less than or equal to 0.1 mm.

9. The lead frame according to claim 8, wherein: The step difference is between 0.01 and 0.04 mm.

10. The lead frame according to claim 7, wherein: The substrate includes a base layer and a plating layer arranged on the second surface. The plurality of step structures are formed on the base layer and the plating layer simultaneously.

11. The lead frame according to claim 7, wherein The substrate has a platform area formed between the plurality of step structures and the tearing area.

12. The lead frame according to claim 11, wherein The substrate includes a base layer and a plating layer arranged on the second surface. The plurality of step structures are formed on the plating layer, and the platform area is formed by the base layer.

13. The lead frame according to claim 7, wherein: The portion of the second surface of the substrate adjacent to the tear zone further has a protrusion, the portion of the protrusion protruding from the second surface is defined by a height, and the maximum distance of the portion of the protrusion protruding from the second surface along the vertical direction of the at least one side surface is defined by a horizontal length, the height of the protrusion does not exceed 0.05 mm, and the horizontal length of the protrusion does not exceed 0.15 mm.

14. The lead frame according to claim 1, wherein The plurality of step structures are arranged at intervals, and a distance between any two adjacent step structures is less than or equal to 0.05 mm.

15. A lead frame sheet, characterized in that: Includes: two tracks, the two tracks being arranged in parallel; and A plurality of lead frames according to any one of claims 1 to 14, wherein the plurality of lead frames are arranged between the two rails.

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