Lead frame structure and packaging structure thereof

Abstract

The invention discloses a lead frame structure and a packaging structure thereof. The lead frame structure comprises a base island; and the pins and the base island are arranged at intervals, entities are arranged on the back surfaces of the pins, the number of the entities on the same pin is one or more, and the back surfaces of the pins are opposite to the device bearing surface of the base island. According to the embodiment of the invention, the entity can support the pins, the probability of deformation caused by insufficient supporting force of the pins is reduced, and the anti-deformation capability of the lead frame structure is correspondingly improved, so that the covering capability of a plastic package material to the pins in a subsequent plastic package process is improved, and the yield of the lead frame structure is improved. The probability that unexpected areas in the pins are exposed is reduced, and the yield of the packaging structure is further improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of semiconductor packaging, and in particular to a lead frame structure and a packaging structure thereof. Background Art

[0002] In recent years, with the rapid development of electronic technology, the requirements for reliability in semiconductor packaging have been increasing. In the packaging process of semiconductor chips, a lead frame is needed to realize the electrical connection between the semiconductor chip and the external circuit, so as to realize the electrical function performed by the semiconductor chip. In addition, the lead frame can also provide physical support for the semiconductor chip.

[0003] The lead frame is a key structural component that realizes the electrical connection between the lead end of the internal circuit of the chip and the external circuit to form an electrical loop. It acts as a bridge connecting with the external circuit. Lead frames are required in most semiconductor integrated blocks. Therefore, lead frames are important basic materials in the electronic information industry.

[0004] Currently, the lead frame structure and packaging structure still need to be improved. Summary of the invention

[0005] The problem solved by the embodiments of the present invention is to provide a lead frame structure and a packaging structure thereof to improve the performance of the packaging structure.

[0006] To solve the above problems, an embodiment of the present invention provides a lead frame structure, including: a base island; a pin, which is spaced apart from the base island, and an entity is arranged on the back of the pin. The number of the entities on the same pin is one or more, and the back of the pin is away from the device bearing surface of the base island.

[0007] Optionally, the lead frame structure includes a frame unit, the frame unit includes the base island and the pins; the frame unit also includes: connecting ribs connecting the base island and the top corners of the frame unit, the connecting ribs and the pins are spaced apart from each other; the entity is located on the pins close to the connecting ribs.

[0008] Optionally, the lead frame structure includes a frame unit, the frame unit includes the base island and the pins; the frame unit also includes: connecting ribs, connecting the base island and the top corners of the frame unit, the connecting ribs and the pins are spaced apart from each other; on either side of the connecting ribs, the entities on adjacent pins are staggered.

[0009] Optionally, on either side of the connecting rib, there are multiple pins, and the layout of entities on the multiple pins includes: positions of entities on different pins are progressive toward the base island.

[0010] Optionally, the entity and the pin are an integral structure; or, the entity is welded on the back side of the pin; or, the entity is pasted on the back side of the pin.

[0011] Optionally, the pin includes an inner pin and an outer pin that are connected, and the outer pin is located at an end of the inner pin away from the base island, and the entity is arranged on the inner pin.

[0012] Optionally, the back side of the pin has a step, and the pin includes an inner pin located at a recessed position of the step, and an outer pin connected to the inner pin.

[0013] Optionally, on the back side of the pin, the bottom of the outer pin is flush with the bottom of the entity.

[0014] Optionally, the width of the entity is less than or equal to the width of the inner pin.

[0015] Optionally, a ratio of the length to the width of the entity is greater than or equal to 2.

[0016] Optionally, the length of the entity is less than or equal to 1 / 2 of the length of the pin where the entity is located.

[0017] Optionally, the shortest distance between adjacent entities located on different pins is greater than or equal to 1.5 times the spacing between adjacent pins.

[0018] Optionally, when there are multiple entities located on the same pin, the distance between the entities on the same pin is greater than or equal to the width of the pin where the entity is located.

[0019] Optionally, the material of the entity includes one or more of tungsten, aluminum, copper, titanium, silver, gold, platinum, nickel, iron and alloys thereof.

[0020] Correspondingly, an embodiment of the present invention also provides a packaging structure, comprising: the lead frame structure described in any embodiment of the present invention; a chip, arranged on the device supporting surface of the base island and electrically connected to the pins; and a plastic encapsulating material, encapsulating the lead frame structure and the chip.

[0021] Optionally, the pin includes an inner pin and an outer pin connected to each other, and the outer pin is located at an end of the inner pin away from the base island, and the entity is arranged on the inner pin; and the molding compound exposes the bottom of the outer pin.

[0022] Optionally, the molding compound exposes the bottom of the entity.

[0023] Optionally, the packaging structure further includes: a solder wetting layer located at the bottom of the external pins and the bottom of the entity exposed to the plastic packaging material.

[0024] Optionally, the thickness of the solder wetting layer ranges from 8 microns to 15 microns.

[0025] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0026] The lead frame structure provided by the embodiment of the present invention includes a base island and pins arranged at intervals, and a solid body is arranged on the back of the pin, which can support the pin, thereby reducing the probability of deformation due to insufficient supporting force of the pin, and correspondingly improving the deformation resistance of the lead frame structure, which is beneficial to improving the covering ability of the plastic encapsulation material on the pin in the subsequent plastic encapsulation process, reducing the probability of undesirable areas in the pin being exposed, and thus improving the yield of the packaging structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the structure of a lead frame structure;

[0028] Figure 2 yes Figure 1 A local enlarged view of area A;

[0029] Figure 3 is a schematic diagram of a package structure with the back side of the pins exposed;

[0030] Figure 4 It is a structural schematic diagram of an embodiment of a lead frame structure of the present invention;

[0031] Figure 5(a) is Figure 4 A partial enlarged view of the first embodiment in area B;

[0032] Figure 5(b) is Figure 4 A partial enlarged view of the second embodiment in area B;

[0033] Figure 5(c) is Figure 4 A partial enlarged view of the third embodiment in area B;

[0034] Figure 5(d) is Figure 4 A partial enlarged view of the fourth embodiment in area B;

[0035] Figure 5(e) is Figure 4 A partial enlarged view of the fifth embodiment in area B;

[0036] Figure 6 yes Figure 4 Cross-sectional view at CC1;

[0037] Figure 7 It is a schematic cross-sectional view of an embodiment of a packaging structure of the present invention. DETAILED DESCRIPTION

[0038] At present, the lead frame structure and the packaging structure still need to be improved. Now, combined with a lead frame structure, the reasons why the lead frame structure and the packaging structure still need to be improved are analyzed. Figure 1 It is a schematic diagram of the structure of a lead frame structure. Figure 2 yes Figure 1 A partial enlarged view of area A. Figure 3 It is a schematic diagram of a package structure with the back side of the pins exposed.

[0039] refer to Figure 1 to Figure 2 The lead frame structure 20 includes: a base island 21 and pins 22, and the pins 22 are spaced from each other and from adjacent pins 22 to each other.

[0040] Usually, the lead frame structure 20 is subjected to film lamination before injection molding. However, studies have found that a lead frame structure 20 with a larger area is prone to insufficient support for its pins 22, so that during the lamination process, the pins 22 of the lead frame structure 20 are prone to deformation, so that during the subsequent process of forming a packaging structure, the pins 22 at the deformed position cannot be completely covered by the plastic molding compound and are exposed from the plastic molding compound (e.g., Figure 3 The defect of “leaking finger” is generated, which in turn affects the yield of the packaging structure.

[0041] In order to solve the above technical problems, an embodiment of the present invention provides a lead frame structure, including: a base island; a pin, which is spaced apart from the base island, and an entity is arranged on the back of the pin. The number of the entities on the same pin is one or more, and the back of the pin is away from the device bearing surface of the base island.

[0042] The lead frame structure provided by the embodiment of the present invention includes a base island and pins arranged at intervals, and a solid body is arranged on the back of the pin, which can support the pin, thereby reducing the probability of deformation due to insufficient supporting force of the pin, and correspondingly improving the deformation resistance of the lead frame structure, which is beneficial to improving the covering ability of the plastic encapsulation material on the pin in the subsequent plastic encapsulation process, reducing the probability of undesirable areas in the pin being exposed, and thus improving the yield of the packaging structure.

[0043] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and understandable, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0044] Figure 4 FIG. 5( a) is a schematic diagram of a lead frame structure according to an embodiment of the present invention. Figure 4 FIG5( b ) is a partial enlarged view of the first embodiment in the B region; ... Figure 4A partial enlarged view of the second embodiment in area B; FIG. 5( c ) is Figure 4 FIG5(d) is a partial enlarged view of the third embodiment in the B area; ... Figure 4 A partial enlarged view of the fourth embodiment in area B, Figure 6 for Figure 4 Cross-sectional view at CC1.

[0045] refer to Figures 4 to 6 In this embodiment, the lead frame structure 100 includes: a base island 110; a pin 120, which is spaced apart from the base island 110, and a back side 125 (such as Figure 6 1) is provided with an entity 130, the number of the entity 130 on the same pin 120 is one or more, the back side 125 of the pin 120 faces away from the device bearing surface 115 of the base island 110 (as shown in FIG. Figure 6 shown).

[0046] The lead frame structure 100 is used to carry a chip and realize electrical connection between the chip and an external circuit.

[0047] In this embodiment, the lead frame structure 100 is used to prepare a leadless packaging structure, including but not limited to a Quad Flat No-leads (QFN) packaging structure.

[0048] In this embodiment, the material of the lead frame structure 100 is metal or alloy. As an example, the material of the lead frame structure 100 can be one or more of tungsten, aluminum, copper, titanium, silver, gold, platinum, nickel, iron and alloys thereof. As an example, the material of the lead frame structure 100 is copper or iron-nickel alloy.

[0049] In this embodiment, the lead frame structure 100 includes a frame unit 101 , and the frame unit 101 includes the base island 110 and the pins 120 .

[0050] The frame unit 101 is used as a basic unit constituting the lead frame structure 100 .

[0051] It should be noted that, as a diagram, this embodiment only illustrates one frame unit 101. The lead frame structure 100 may include a plurality of frame units 101.

[0052] The shape of the frame unit 101 is a polygon. In this embodiment, the shape of the frame unit 101 is a square. As an example, the shape of the frame unit 101 is a square.

[0053] Therefore, the frame unit 101 has corners, for example, the square frame unit 101 has four corners.

[0054] In other embodiments, the shape of the frame unit may also be other suitable shapes.

[0055] The base island 110 is used as a platform for carrying chips. Accordingly, the base island 110 has a device carrying surface 115, and the device carrying surface 115 of the base island 110 is used to place chips.

[0056] The base island 110 is in a polygonal shape. In this embodiment, the base island 110 is in a square shape. As an example, the base island 110 is in a square shape.

[0057] Therefore, the base island 110 has a vertex, for example, the square-shaped base island 110 has four vertexes.

[0058] In other embodiments, the shape of the base island may also be other appropriate shapes.

[0059] One end of the pin 120 is used to be electrically connected to the chip, and the other end of the pin 120 is used to be electrically connected to an external circuit.

[0060] It should be noted that the number of the pins 120 may be one or more. In this embodiment, the number of the pins 120 is multiple, and correspondingly, adjacent pins 120 are spaced apart from each other.

[0061] In this embodiment, the plurality of pins 120 are distributed around the base island 110 .

[0062] In this embodiment, the pin 120 includes an inner pin 121 and an outer pin 122 which are connected to each other, and the outer pin 122 is located at an end of the inner pin 121 away from the base island 110 .

[0063] The inner pins 121 are used to be electrically connected to the chip, and are used to connect the outer pins 122 and the entity 130 .

[0064] The external pins 122 are used as pin pads for electrically connecting to an external circuit. Specifically, the external pins 122 are usually used for soldering to a substrate (eg, a PCB).

[0065] The outer pin 122 is located at an end of the inner pin 121 away from the base island 110 , which is beneficial to increase the distance between adjacent outer pins 122 , thereby reducing the probability of short circuit between adjacent outer pins 122 .

[0066] In this embodiment, the back side 125 of the pin 120 has a step, and the pin 120 includes an inner pin 121 located at the recessed position of the step, and an outer pin 122 connected to the inner pin 121. This facilitates the subsequent molding process, so that the molding compound covers the inner pin 121 and exposes the bottom 126 of the outer pin 122, and also helps to increase the bonding strength between the molding compound and the pin 120.

[0067] In this embodiment, the frame unit 101 further includes: a connecting rib 140 connecting the base island 110 and the top corner of the frame unit 101 , and the connecting rib 140 and the pin 120 are spaced apart from each other.

[0068] The connecting ribs 140 are used to connect the base island 110 to the top corners of the frame unit 101 to fix the base island 110 .

[0069] In this embodiment, the base island 110 is in a square shape and has a vertex, so the connecting rib 140 connects the base island 110 and the oppositely disposed vertex of the frame unit 101. For example, the connecting rib 140 may extend along the diagonal direction of the frame unit 101.

[0070] It should be noted that the frame unit 101 and the base island 110 are generally concentrically arranged in a square shape. In order to facilitate the arrangement of the pins 120 , the connecting ribs 140 are usually located at the diagonal position of the frame unit 101 .

[0071] It can be understood that since the distance from the top corner of the frame unit 101 to the base island 110 is the farthest, the length of the pin 120 close to the connecting rib 140 is correspondingly greater than the length of the pin 120 far from the connecting rib 140, that is, the length of the pin 120 adjacent to the connecting rib 140 is the largest.

[0072] As an example, the four vertices of the base island 110 are respectively connected to the vertices of the frame unit 101 through four connecting bars 140 .

[0073] In this embodiment, the frame unit 101 further includes: side ribs 150 located at the edge of the frame unit 101 , the side ribs 150 surround the pins 120 and the base island 110 , and the side ribs 150 connect the pins 120 along the circumference of the frame unit 101 .

[0074] Correspondingly, the connecting reinforcement 140 connects the base island 110 and the side reinforcement 150 at the top corner position of the frame unit 101 .

[0075] It should be noted that in order to clearly show the lead frame structure, Figure 6 The side reinforcement is omitted.

[0076] The side ribs 150 are used to fix the pins 120 and the connecting ribs 140 before plastic packaging.

[0077] It should be noted that, when the lead frame structure 100 includes a plurality of frame units 101 , adjacent frame units 101 may share the same side rib 150 .

[0078] It should also be noted that after the lead frame structure 100 and the chip are encapsulated with the encapsulating material, the side ribs 150 need to be cut and removed to separate the pins 120 from each other and to separate the adjacent pins 120 from the connecting ribs 140 from each other.

[0079] The entity 130 can support the pin 120, reducing the probability of deformation due to insufficient supporting force of the pin 120, and correspondingly improving the ability of the lead frame structure 100 to resist deformation, which is beneficial to improving the covering ability of the molding compound on the pin 120 in the subsequent molding process, reducing the probability of undesired areas of the pin 120 being exposed, and thereby improving the yield of the packaging structure.

[0080] In this embodiment, the entity 130 is disposed on the back side 125 of the pin 120 , and the back side 125 of the pin 120 refers to: the surface of the pin 120 opposite to the device carrying surface 115 of the base island 110 .

[0081] In this embodiment, the pin 120 includes an inner pin 121 and an outer pin 122 which are connected to each other. The outer pin 122 is the portion of the pin 120 to be exposed, and the inner pin 121 is the portion of the pin 120 to be plastic-encapsulated. Therefore, the entity 130 is provided on the inner pin 121 to support the inner pin 121, thereby reducing the probability of the inner pin 121 being exposed.

[0082] Specifically, the back side 125 of the pin 120 has a step, and the pin 120 includes an inner pin 121 located at a recessed position of the step. In other words, the thickness of the inner pin 121 is smaller or the length is longer, and the inner pin 121 is more likely to deform. Therefore, by setting the entity 130 on the inner pin 121, it is easier to meet the thickness and length requirements of the inner pin 121, thereby meeting the size requirements of the package structure formed by the frame unit 101. For example, when the size of the package structure without pins increases, the required length of the pin 120 increases. By setting the entity 130, it is convenient to use an inner pin 121 with a longer length.

[0083] The number of the entities 130 on the same pin 120 may be one or more.

[0084] As shown in Figure 5(a), Figure 5(b) or Figure 5(c), in some embodiments, the number of the entities 130 on the same pin 120 is one; as shown in Figure 5(d) or Figure 5(e), in other embodiments, the number of the entities 130 on the same pin 120 may also be multiple.

[0085] In order to enable the entity 130 to provide a better supporting effect on the pin 120, the number of entities 130 on the same pin 120 can be determined according to the length of the pin 120, that is, when the length value of the pin 120 is small, one entity 130 is set on the back side 125 of the same pin 120, and when the length value of the pin 120 is large, multiple entities 130 are set on the back side 125 of the same pin 120. For example, when the length value of the pin 120 is large, two entities 130 are set on the back side 125 of the same pin 120, that is, according to the length of the pin 120, the appropriate number of entities 130 is selected. It can be understood that the number of entities 130 on the back side 125 of the same pin 120 is not limited to two, and can also be three, four, etc.

[0086] It should be noted that, when there are multiple entities 130 located on the same pin 120, the distance between the entities 130 on the same pin 120 should not be too small. If the distance between the entities 130 on the same pin 120 is too small, it is easy to increase the difficulty of forming the entity 130. Therefore, in this embodiment, when there are multiple entities 130 located on the same pin 120, the distance between the entities 130 on the same pin 120 is greater than or equal to the width of the pin 120 where the entity 130 is located.

[0087] In this embodiment, the entity 130 is located on the pin 120 close to the connecting rib 140 .

[0088] Compared with short pins, the problem of insufficient supporting force of long pins is particularly prominent, and long pins are also more prone to deformation. The length of the pin 120 adjacent to the connecting rib 140 is the largest. Therefore, when the entity 130 is set on the pin 120 close to the connecting rib 140, the entity 130 can better play the role of improving the insufficient supporting force of the pin 120.

[0089] In this embodiment, on any side of the connecting rib 140 , the layout of the entities 130 on the plurality of pins 120 includes: the entities 130 on adjacent pins 120 are staggered.

[0090] On either side of the connecting rib 140 , the entities 130 on adjacent pins 120 are staggered, which is beneficial to increase the distance between the entities 130 on adjacent pins 120 , thereby facilitating reducing the probability of short circuits between the entities 130 on adjacent pins 120 .

[0091] For example, after the lead frame structure 100 and the chip are encapsulated by the encapsulation material to form a package structure, the package structure needs to be soldered to the substrate through the solder wetting layer. Therefore, when the bottom 135 of the entity 130 is exposed by the encapsulation material, the entities 130 on adjacent pins 120 are staggered, which is conducive to reducing the probability of short circuits between the entities 130 on adjacent pins 120 due to the connection of the solder wetting layer.

[0092] As an example, as shown in Figure 5(a), on either side of the connecting rib 140, the number of the pins 120 is multiple, and the layout of the entities 130 on the multiple pins 120 includes: the positions of the entities 130 on different pins 120 are progressive toward the base island 110.

[0093] That is, on any side of the connecting rib 140 , the closer the entity 130 on the pin 120 is to the connecting rib 140 , the greater the distance from the entity 130 to the base island 110 .

[0094] Since the length of the pin 120 adjacent to the connecting rib 140 is the largest, that is, the smaller the distance from the pin 120 to the connecting rib 140, the longer the length of the pin 120. Correspondingly, the longer the pin 120, the smaller the supporting force of the end close to the base island 110. The layout of the entities 130 on the plurality of pins 120 is a progressive arrangement, that is, on the longer pin 120, the entity 130 is closer to the base island 110, so that the entity 130 can support the end of the pin 120 close to the base island 110, thereby facilitating the entity 130 to support the pin 120 better.

[0095] As shown in FIG. 5( b ) or FIG. 5( c ), in other specific embodiments, on either side of the connecting rib 140 , the layout of the entities 130 on the plurality of pins 120 may also only satisfy that: the entities 130 on adjacent pins 120 are staggered.

[0096] It should be noted that, at multiple vertex positions of the frame unit 101 , the layout of the entities 130 may be the same or different, as long as the undesired areas in the pins 120 can be plastic-sealed.

[0097] For example, the layout of entity 130 may include Figure 5(a) to Figure 5(e) Any one or more of .

[0098] It should also be noted that the layouts of the entities 130 on both sides of the same connecting rib 140 may be the same or different.

[0099] In this embodiment, the material of the entity 130 includes one or more of tungsten, aluminum, copper, titanium, silver, gold, platinum, nickel, iron and alloys thereof. As an example, the material of the entity 130 is copper or iron-nickel alloy. The hardness of metal or metal alloy material is relatively large, so it can support the pin 120.

[0100] In other embodiments, the material of the entity may also be other suitable materials, such as non-metal.

[0101] In this embodiment, the entity 130 and the pin 120 are an integrated structure, and accordingly, the entity 130 and the pin 120 are made of the same material.

[0102] The entity 130 and the pin 120 are an integrated structure, which improves the bonding strength between the entity 130 and the pin 120. Moreover, the entity 130 and the pin 120 can be formed by the same process, which reduces the complexity of preparing the pin 120 and the entity 130.

[0103] It should be noted that, in other embodiments, the entity and the pin may also be a non-integrated structure. For example, the entity may also be welded to the back of the pin or adhered to the back of the pin through an adhesive film.

[0104] In this embodiment, on the back side 125 of the pin 120 , the bottom 126 of the outer pin 122 is flush with the bottom 135 of the entity 130 .

[0105] On the one hand, the bottom 126 of the external pin 122 is flush with the bottom 135 of the entity 130, which is beneficial to increase the thickness of the entity 130, thereby further enhancing the supporting effect of the entity 130 on the pin 120, and correspondingly further improving the deformation resistance of the lead frame structure 100.

[0106] Moreover, the inner pin 121 is located in the half-etched area of ​​the pin 120, that is, the step 125 on the back side of the pin 120 can be formed by an etching process. Therefore, when the entity 130 and the pin 120 are an integrated structure, the bottom 126 of the outer pin 122 is flush with the bottom 135 of the entity 130, which is convenient for obtaining the outer pin 122 and the entity 130 at the same time, which is beneficial to reducing the process complexity of forming the pin 120 and the entity 130.

[0107] On the other hand, the bottom 126 of the external lead 122 is flush with the bottom 135 of the body 130 , which helps to improve the flatness of the bottom of the lead frame structure 100 , thereby facilitating subsequent plastic encapsulation processing.

[0108] Furthermore, because the bottom 126 of the external pin 122 is flush with the bottom 135 of the entity 130, after the plastic encapsulation process, the plastic encapsulation material can expose the bottom 126 of the external pin 122 while also exposing the bottom 135 of the entity 130, so that when the external pin 122 is subsequently welded to the substrate, the entity 130 is also welded to the substrate, thereby improving the bonding strength between the packaging structure and the substrate.

[0109] It should be noted that, in other embodiments, the bottom of the entity may also be higher than the bottom of the external pins, that is, the bottom of the entity is closer to the device carrying surface 115 of the base island 110 .

[0110] It should also be noted that the width W1 of the entity 130 (as shown in FIG. 5( a )) is less than or equal to the width W2 of the inner pin 121 (as shown in FIG. 5( a )).

[0111] The width W1 of the entity 130 is less than or equal to the width W2 of the inner pin 121 , so that there is a spacing between the entities 130 located on adjacent inner pins 121 , thereby helping to reduce the probability of short circuit problems between the entities 130 located on adjacent inner pins 121 .

[0112] As an example, the width W1 of the entity 130 is equal to the width W2 of the inner pin 121 .

[0113] The width W1 of the entity 130 is equal to the width W2 of the inner pin 121 , which helps to further reduce the complexity of manufacturing the pin 120 and the entity 130 .

[0114] As shown in FIG. 5( a ), the ratio of the length L1 to the width W1 of the entity 130 should not be too small. If the ratio of the length L1 to the width W1 of the entity 130 is too small, it is easy for the length L1 of the entity 130 to be too small when the width W1 of the entity 130 is constant, so that the surface area of ​​the entity 130 is too small, and it is easy for the entity 130 to have a poor support effect on the pin 120, which is easy to lead to unsatisfactory effect of improving the anti-deformation effect of the lead frame structure 100. Therefore, in this embodiment, the ratio of the length L1 to the width W1 of the entity 130 is greater than or equal to 2.

[0115] The length L1 of the entity 130 should not be too large. If the length L1 of the entity 130 is too large, when the package structure including the lead frame structure 100 is welded to the substrate, the risk of short circuit between the entities 130 on adjacent pins 120 is easily increased. Therefore, in this embodiment, the length L1 of the entity 130 is less than or equal to 1 / 2 of the length of the pin 120 where the entity 130 is located.

[0116] In this embodiment, the shortest distance between adjacent entities 130 located on different pins 120 is greater than or equal to 1.5 times the spacing between adjacent pins 120. Since a solder wetting layer will be formed on the bottom 135 surface of the entity 130 later, and the size of the solder wetting layer will be larger than the size of the bottom 135 surface of the entity 130, by setting the shortest distance between adjacent entities 130 located on different pins 120 to be greater than or equal to 1.5 times the spacing between adjacent pins 120, it is helpful to reduce the probability of short circuit between adjacent entities 130 on different pins 120.

[0117] Correspondingly, the present invention also provides a packaging structure. Figure 7 It is a schematic cross-sectional view of an embodiment of a packaging structure of the present invention.

[0118] refer to Figure 7 , and combined with reference Figures 4 to 6 The packaging structure 200 includes: the lead frame structure 100 described in any of the above embodiments; a chip 210, which is arranged on the device carrying surface 115 of the base island 110 and is electrically connected to the pin 120; and a plastic encapsulation material 220, which encapsulates the lead frame structure 100 and the chip 210.

[0119] The entity 130 can support the pin 120, reducing the probability of deformation due to insufficient supporting force of the pin 120, and correspondingly improving the ability of the lead frame structure 100 to resist deformation, which is beneficial to improving the covering ability of the plastic encapsulation material 220 on the pin 120 in the plastic encapsulation process, reducing the probability of exposure of the undesirable exposed area of ​​the pin 120, thereby improving the performance of the packaging structure 200.

[0120] In this embodiment, the package structure 200 is a quad flat no-lead (QFN) package structure. In other embodiments, the package structure may also be other types of package structures, which will not be described one by one here.

[0121] For a detailed description of the lead frame structure 100 , reference may be made to the contents of the aforementioned embodiments, which will not be repeated here.

[0122] The chip 210 is disposed on the device carrying surface 115 of the base island 110 , and the chip 210 is electrically connected to the pins 120 , thereby obtaining a packaging structure with certain functions to achieve the functional requirements of the product.

[0123] In this embodiment, the package structure 200 further includes: a lead 230 connecting the chip 210 and the pin 120. The lead 230 is used to achieve electrical connection between the chip 210 and the pin 120. Specifically, the material of the lead 230 is a conductive metal.

[0124] The molding compound 220 is used to protect the chip 210 from mechanical shock, wear and environmental factors (such as humidity changes, etc.), and to mold the chip 210 and the lead frame structure 100 into a whole to obtain a packaging structure.

[0125] It should be noted that the lead frame structure 100 in the packaging structure is a cut lead frame structure 100 , and therefore, as an example, the lead frame structure 100 in the packaging structure includes only one frame unit 101 .

[0126] In this embodiment, the pin 120 includes an inner pin 121 and an outer pin 122 which are connected to each other, and the outer pin 122 is located at an end of the inner pin 121 away from the base island 110 .

[0127] The external pins 122 are used as pin pads for electrically connecting to an external circuit. Therefore, the molding compound 220 exposes the bottom 126 of the external pins 122 to electrically connect the pins 120 to an external circuit.

[0128] In this embodiment, the material of the plastic encapsulation material 220 includes epoxy resin. Epoxy resin has the advantages of low shrinkage, good adhesion, good corrosion resistance, excellent electrical properties and low cost. In other embodiments, the plastic encapsulation material can also be selected from other suitable packaging materials.

[0129] In this embodiment, the entity 130 is disposed on the inner pin 121 , so the molding compound 220 also exposes the bottom 135 of the entity 130 .

[0130] The molding compound 220 also exposes the bottom 135 of the entity 130 , that is, the thickness H1 of the entity 130 is relatively large, which is beneficial to enhancing the supporting effect of the entity 130 on the inner pin 121 , and correspondingly also beneficial to further improving the anti-deformation capability of the lead frame structure 100 .

[0131] Moreover, the molding compound 220 also exposes the bottom 135 of the entity 130, so that when the back side 125 of the pin 120 exposed by the molding compound 220 is subsequently welded to the substrate, the entity 130 is also welded to the substrate, thereby improving the bonding strength between the packaging structure 200 and the substrate.

[0132] Specifically, the packaging structure 200 further includes: a solder wetting layer 240 located at the bottom 126 of the external lead 122 and the bottom 135 of the body 130 exposed to the molding compound 220 .

[0133] The solder wetting layer 240 is located at the bottom 126 of the external lead 122 and the bottom 135 of the body 130 exposed to the molding compound 220 , so that the package structure 200 is soldered on the substrate through the solder wetting layer 240 .

[0134] It should be noted that the thickness of the solder wetting layer 240 should not be too small or too large. If the thickness of the solder wetting layer 240 is too small, the package structure 200 may not be firmly soldered to the substrate; if the thickness of the solder wetting layer 240 is too large, the probability of short circuit of the entities 130 on adjacent pins 120 may increase. Therefore, as an example, the thickness of the solder wetting layer 240 is in the range of 8 microns to 15 microns.

[0135] In this embodiment, the material of the solder wetting layer 240 may include one or more alloys of tin, nickel, palladium and silver. As an example, the material of the solder wetting layer 240 is tin.

[0136] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A lead frame structure, characterized in that: include: Key Island; The pin is spaced apart from the base island, an entity is arranged on the back of the pin, the number of the entities on the same pin is one or more, and the back of the pin faces away from the device bearing surface of the base island.

2. The lead frame structure according to claim 1, characterized in that: The lead frame structure comprises a frame unit, and the frame unit comprises the base island and the pins; The frame unit further includes: a connecting rib connecting the base island and the top corner of the frame unit, wherein the connecting rib and the pin are spaced apart from each other; The entity is located on a pin close to the connecting bar.

3. The lead frame structure according to claim 1, characterized in that: The lead frame structure comprises a frame unit, and the frame unit comprises the base island and the pins; The frame unit further comprises: a connecting rib connecting the base island and the top corner of the frame unit, wherein the connecting rib and the pin are spaced apart from each other; On either side of the connecting rib, entities on adjacent pins are staggered.

4. The lead frame structure according to claim 3, characterized in that: On either side of the connecting rib, there are a plurality of pins, and the layout of entities on the plurality of pins includes: positions of entities on different pins are progressive toward the base island.

5. The lead frame structure according to claim 1, wherein: The entity and the pin are an integrated structure; Alternatively, the entity is welded on the back side of the pin; Alternatively, the entity is attached to the back side of the pin.

6. The lead frame structure according to any one of claims 1 to 5, characterized in that: The pins include an inner pin and an outer pin which are connected to each other, and the outer pin is located at an end of the inner pin away from the base island, and the entity is arranged on the inner pin.

7. The lead frame structure according to claim 6, characterized in that: The back side of the pin has a step, and the pin includes an inner pin located at a recessed position of the step, and an outer pin connected to the inner pin.

8. The lead frame structure according to claim 6, characterized in that: On the back side of the pin, the bottom of the outer pin is flush with the bottom of the entity.

9. The lead frame structure according to claim 6, characterized in that: The width of the entity is less than or equal to the width of the inner pin.

10. The lead frame structure according to any one of claims 1 to 5, characterized in that: The ratio of the length to the width of the entity is greater than or equal to 2.

11. The lead frame structure according to any one of claims 1 to 5, characterized in that: The length of the entity is less than or equal to 1 / 2 of the length of the pin where the entity is located.

12. The lead frame structure according to any one of claims 1 to 5, characterized in that: The shortest distance between adjacent entities located on different pins is greater than or equal to 1.5 times the spacing between adjacent pins.

13. The lead frame structure according to any one of claims 1 to 5, characterized in that: When there are multiple entities on the same pin, the distance between the entities on the same pin is greater than or equal to the width of the pin where the entity is located.

14. The lead frame structure according to any one of claims 1 to 5, characterized in that: The material of the entity includes one or more of tungsten, aluminum, copper, titanium, silver, gold, platinum, nickel, iron and alloys thereof.

15. A packaging structure, characterized in that: include: The lead frame structure according to any one of claims 1 to 14; A chip, arranged on the device carrying surface of the base island and electrically connected to the pins; A plastic encapsulation material is used to encapsulate the lead frame structure and the chip.

16. The packaging structure according to claim 15, characterized in that: The pin comprises an inner pin and an outer pin which are connected to each other, and the outer pin is located at an end of the inner pin away from the base island, and the entity is arranged on the inner pin; The molding compound exposes the bottom of the external pin.

17. The packaging structure according to claim 16, characterized in that: The molding compound exposes the bottom of the entity.

18. The packaging structure according to claim 17, characterized in that: The packaging structure further comprises: a solder wetting layer located at the bottom of the outer pins and the bottom of the entity exposed to the plastic packaging material.

19. The packaging structure according to claim 18, characterized in that: The thickness of the solder wetting layer is in a range of 8 micrometers to 15 micrometers.

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