Lead frame structure

Abstract

A lead frame structure includes an insulating layer, a patterned conductive layer and at least one conductive pillar. The insulating layer is provided with an upper surface and a lower surface which are oppositely arranged. The patterned conductive layer is arranged on the upper surface of the insulating layer in a protruding manner and is not covered by the insulating layer. The periphery of the conductive column is in a majority step layer shape, and the conductive column is embedded in the insulating layer. Wherein the uppermost step layer of the conductive column is arranged on the upper surface of the insulating layer in a protruding manner and is not covered by the insulating layer, and the bottom side surface of the lowermost layer of the conductive column is exposed out of the lower surface of the insulating layer.

Description

Technical Field

[0001] The utility model relates to a wire frame structure. Background Art

[0002] Lead frame packaging is a packaging technology that uses a lead frame as a structure to connect the chip and other package components. The core component of the lead frame package is the lead frame, which provides the wire structure required to connect the chip to other parts of the package (such as pins or ball grid array).

[0003] Figure 1 A conventional lead frame package structure 10 is shown. The lead frame package structure 10 includes an insulating substrate 11 and a conductive element 13. The insulating substrate 11 has a plurality of openings 15, and the conductive element 13 is filled in the openings 15. In addition, the conductive element 13 also has a carrying surface 131 and a plurality of electrical contacts 133 on a surface 111 of the insulating substrate 11. A chip 17 can be placed on the carrying surface 131, and the electrical wires 171 of the chip 17 can be electrically connected to the electrical contacts 133.

[0004] The bonding between the conductive element 13 and the insulating substrate 11 of the lead frame package structure 10 is only maintained by the roughness of the bonding surface of the two, and the bonding strength is obviously insufficient. After the subsequent semiconductor process or actual use at the product end, it is easy to cause the bonding surface to peel off or fall off, resulting in failure.

[0005] Therefore, how to provide a lead frame structure to enhance the bonding strength between the conductive component and the insulating substrate is one of the current important issues. Utility Model Content

[0006] An object of the utility model is to provide a lead frame structure, which can strengthen the bonding strength between the insulating layer and the conductive structure of the lead frame structure and improve the durability.

[0007] To achieve the above-mentioned purpose, the utility model provides a lead frame structure, which includes an insulating layer, a patterned conductive layer and at least one conductive column. The insulating layer has an upper surface and a lower surface arranged opposite to each other. The patterned conductive layer is protrudingly arranged on the upper surface of the insulating layer and is not covered by the insulating layer. The conductive column is in a plurality of step layers and is embedded in the insulating layer. The uppermost step layer of the conductive column is protrudingly arranged on the upper surface of the insulating layer and is not covered by the insulating layer, and the bottom side surface of the lowermost step layer of the conductive column is exposed on the lower surface of the insulating layer.

[0008] In one embodiment, the width of each level of the level layers around the conductive pillar decreases from top to bottom.

[0009] In one embodiment, the number of the plurality of level layers around the conductive pillar is at least three, and the width of the middle level layer is smaller than the width of the upper level layer and the lower level layer.

[0010] In one embodiment, the material of the insulating layer is selected from photosensitive or non-photosensitive organic dielectric materials, including Ajinomoto build-up layer film, poly(p-oxadiazole benzene), polyimide, prepreg with glass fiber, epoxy resin, molding material, bismaleimide triazine resin.

[0011] In one embodiment, the material of the patterned conductive layer and the conductive pillars includes pure copper, copper alloy or nickel alloy.

[0012] In one embodiment, the upper surface of the patterned conductive layer is coplanar with the upper surface of the conductive pillar.

[0013] As described above, the lead frame structure of the present invention increases the contact area between the insulating layer and the conductive column and thus improves the bonding strength by designing the contact surface between the insulating layer and the conductive column to be a multi-layer structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The figure is a schematic diagram showing a conventional lead frame packaging structure.

[0015] Figure 2 It is a schematic diagram showing a lead frame structure according to the first embodiment of the present invention.

[0016] Figure 3 FIG. 1 is a schematic diagram showing a lead frame structure according to a second embodiment of the present invention.

[0017] Figure 4 A schematic diagram showing a packaging application of the lead frame structure of the present invention.

[0018] Figure 5 It is a schematic diagram showing another packaging application of the lead frame structure of the present invention.

[0019] Description of reference numerals:

[0020] 10: Lead frame packaging structure

[0021] 11: Insulation substrate

[0022] 111: Surface

[0023] 13: Conductive components

[0024] 131: Load-bearing surface

[0025] 133: Electrical contact

[0026] 15: Opening

[0027] 17: Chip

[0028] 171: Electrical wire

[0029] 20, 30: Lead frame structure

[0030] 21, 31: Insulation layer

[0031] 211, 221, 234, 311, 321, 334: upper surface

[0032] 212, 235, 312, 335: lower surface

[0033] 213, 313: opening

[0034] 22, 32: Patterned conductive layer

[0035] 23, 33: Conductive column

[0036] 231, 331: First class

[0037] 232, 332: Second level

[0038] 233, 333: The third class

[0039] 235, 335: bottom side

[0040] 40: First semiconductor package

[0041] 41, 51: Semiconductor chips

[0042] 42, 52: Packaging materials

[0043] 411: Electrical wire

[0044] 50: Second semiconductor package

[0045] 511: Conductive bump. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to understand the contents of the present invention and to implement the contents of the present invention accordingly, appropriate embodiments and drawings are described as follows.

[0047] Figure 2 The first embodiment of the present invention is a lead frame structure 20. Figure 2As shown, the lead frame structure 20 includes an insulating layer 21, a patterned conductive layer 22 and two conductive pillars 23. The material of the insulating layer 21 can be selected from photosensitive or non-photosensitive organic dielectric materials, including Ajinomoto build-up film materials, poly(p-oxadiazole benzene), polyimide, prepreg with glass fiber, epoxy resin, molding material, bismaleimide triazine resin or other dielectric materials. The material of the patterned conductive layer 22 and the conductive pillars 23 may include pure copper, copper alloy or nickel alloy. In addition, the lead frame structure 20 of this embodiment can be applied to a quad flat no lead package (Quad Flat No Lead, QFN).

[0048] The insulating layer 21 has an upper surface 211 and a lower surface 212 that are opposite to each other, and an opening 213 that penetrates the upper surface 211 and the lower surface 212 , wherein the opening 213 is in a multi-level hole shape.

[0049] The patterned conductive layer 22 is protruding from the upper surface 211 of the insulating layer 21 . Therefore, the patterned conductive layer 22 is not covered by the insulating layer 21 .

[0050] The conductive pillar 23 is embedded in the insulating layer 21 corresponding to the opening 213. The conductive pillar 23 has a plurality of layers, including a first layer 231, a second layer 232, and a third layer 233 from top to bottom. The first layer 231 located at the top is protruding from the upper surface 211 of the insulating layer 21 and is not covered by the insulating layer 21, and a portion of the first layer 231 is disposed on the upper surface 211 of the insulating layer 21. The conductive pillar 23 also has an upper surface 234, which is coplanar with an upper surface 221 of the patterned conductive layer 22, but whether the two are coplanar or not is not limited thereto.

[0051] In addition, a bottom side 235 of the third level layer 233 of the conductive pillar 23 is exposed to the lower surface 212 of the insulating layer 21, and can be used as an electrode for external connection. Moreover, the bottom side 235 is retracted from the lower surface 212 of the insulating layer 21. In other embodiments, the bottom side 235 of the third level layer 233 can also be coplanar with the lower surface 212 of the insulating layer 21, which is not limited here.

[0052] In this embodiment, the first step layer 231, the second step layer 232 and the third step layer 233 each have a width that decreases from top to bottom. That is, the width of the first step layer 231 is greater than the width of the second step layer 232, and the width of the second step layer 232 is greater than the width of the third step layer 233. Under this structure, the step layered body of the conductive column 23 can be tightly combined with the insulating layer 21 and have a better bonding strength to prevent the conductive column 23 from being separated from the insulating layer 21.

[0053] For example Figure 2As shown, the upper surface 221 of the patterned conductive layer 22 and the upper surface 234 of the conductive pillar 23 can be used as conductive contacts, electrical transmission wires, and component connection planes. For example, when the lead frame structure is applied to a wire bonding package, the connection plane can be used to connect the semiconductor chip, and the conductive contacts can be used as connecting wires to connect the semiconductor chip. In other embodiments, when the lead frame structure is applied to a flip chip package, the connection plane and the conductive contacts can both be used as electrode contacts (or electrode connection pads) for signal transmission.

[0054] then, Figure 3 FIG. 2 is a schematic diagram showing a lead frame structure 30 according to a second embodiment of the present invention. Figure 3 As shown, the lead frame structure 30 has an insulating layer 31, a patterned conductive layer 32 and two conductive pillars 33. The insulating layer 31 has an upper surface 311 and a lower surface 312 disposed opposite to each other, and an opening 313 penetrating the upper surface 311 and the lower surface 312, wherein the opening 313 is a multi-level hole shape.

[0055] The patterned conductive layer 32 is protruding from the upper surface 311 of the insulating layer 31 . Therefore, the patterned conductive layer 32 is not covered by the insulating layer 31 .

[0056] The conductive pillar 33 is embedded in the insulating layer 31 corresponding to the opening 313. The conductive pillar 33 is in a stepped shape, and has a first step layer 331, a second step layer 332, and a third step layer 333 in order from top to bottom. The first step layer 331 located at the top is protruding from the upper surface 311 of the insulating layer 31 and is not covered by the insulating layer 31, and a portion of the first step layer 331 is disposed on the upper surface 311 of the insulating layer 31. The conductive pillar 33 also has an upper surface 334, which is designed to be coplanar with the upper surface 321 of the patterned conductive layer 32, but whether the two are coplanar or not is not limited to this.

[0057] In addition, a bottom side surface 335 of the third level layer 333 of the conductive pillar 33 is exposed to the lower surface 312 of the insulating layer 31, and can be used as an electrode for external connection. Moreover, the bottom side surface 335 is retracted from the lower surface 312 of the insulating layer 31. In other embodiments, the bottom side surface 335 of the third level layer 333 can also be coplanar with the lower surface 312 of the insulating layer 31, which is not limited here.

[0058] In this embodiment, the first step layer 331, the second step layer 332 and the third step layer 333 each have a width. The width of the second step layer 332 is smaller than the widths of the first step layer 331 and the third step layer 333. Under this structure, the step-layered circumference of the conductive column 33 can be tightly combined by sandwiching the insulating layer 31 above and below, thereby providing a better structural bonding strength to prevent the conductive column 33 from being separated from the insulating layer 31.

[0059] Figure 4 and Figure 5 This is a schematic diagram showing the packaging application of the lead frame structure of the utility model. Figure 4 As shown, a first semiconductor package 40 has the lead frame structure 20 as described above, a semiconductor chip 41 and a packaging material 42. The semiconductor chip 41 is a wire bonding package type chip, which can be placed on the upper surface 234 of the conductive pillar 23 by, for example, adhesive, and wire bonded with a portion of the patterned conductive layer 22 as a conductive contact through an electrical wire 411. The packaging material 42 covers the lead frame structure 20 and the semiconductor chip 41 to form the first semiconductor package 40.

[0060] For example Figure 5 As shown, a second semiconductor package 50 has the lead frame structure 30 as described above, a semiconductor chip 51 and a packaging material 52. The semiconductor chip 51 is a flip chip package type chip, which is electrically connected to a portion of the upper surface 321 of the patterned conductive layer 32 and a portion of the upper surface 334 of the conductive pillar 33 through, for example, a conductive bump 511. The packaging material 52 covers the lead frame structure 30 and the semiconductor chip 51 to form the second semiconductor package 50.

[0061] In summary, the lead frame structure of the present invention designs the bonding surface of the conductive column and the insulating layer to be in a stepped layer shape to increase the bonding strength between the two, thereby increasing the overall structural strength and reliability of the lead frame structure.

[0062] The above embodiments are only used to list the implementation modes of the utility model and to explain the technical features of the utility model, and are not used to limit the protection scope of the utility model. Any changes or equivalent arrangements that can be easily completed by those familiar with this technology belong to the scope claimed by the utility model, and the scope of protection of the utility model shall be based on the claims.

Claims

1. A lead frame structure, characterized in that: include: An insulating layer having an upper surface and a lower surface disposed opposite to each other; a patterned conductive layer, protrudingly disposed on the upper surface of the insulating layer and not covered by the insulating layer; as well as At least one conductive column has a plurality of stepped layers around it and is embedded in the insulating layer, wherein the uppermost stepped layer of the at least one conductive column protrudes above the upper surface of the insulating layer and is not covered by the insulating layer, and the bottom side surface of the lowermost layer of the at least one conductive column is exposed on the lower surface of the insulating layer.

2. The lead frame structure according to claim 1, wherein: The width of each of the plurality of level layers around the at least one conductive column decreases from top to bottom.

3. The lead frame structure according to claim 1, wherein: The number of the step layers around the at least one conductive column is at least three, and the width of the middle step layer is smaller than the width of the upper step layer and the lower step layer.

4. The lead frame structure according to claim 1, wherein: The material of the insulating layer is selected from one of photosensitive and non-photosensitive organic dielectric materials.

5. The lead frame structure according to claim 1, wherein: The material of the insulating layer is selected from one of Ajinomoto build-up film, poly(p-oxadiazole benzene), polyimide, prepreg with glass fiber, epoxy resin, and bismaleimide triazine resin.

6. The lead frame structure according to claim 1, wherein: The insulating layer is made of a molding material.

7. The lead frame structure according to claim 1, wherein: The material of the patterned conductive layer and the at least one conductive column includes pure copper, copper alloy or nickel alloy.

8. The lead frame structure according to claim 1, wherein: The upper surface of the patterned conductive layer is coplanar with the upper surface of the at least one conductive column.

Images