A chip package structure based on a flexible substrate

Abstract

The application provides a flexible substrate-based packaging structure, which comprises a flexible substrate, the flexible substrate is inwardly bent in a U shape at two ends, and has a first part and a second part which are opposite and parallel; the second part is provided with a plated through hole which penetrates the flexible substrate in a thickness direction; a first heat dissipation member is arranged on a surface of the second part which is opposite to the first part; a first chip is arranged on a surface of the first part which faces the second part; a front surface of the first chip faces the second part; a second heat dissipation member is connected to the front surface of the first chip and connected to the first heat dissipation member through the plated through hole. The flexible substrate-based packaging structure provided by the application can improve the heat dissipation capacity of the packaging structure, avoid the risk of melting of a bonding wire, and the wire bonding process is simple.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chip packaging, in particular to a chip packaging structure based on a flexible substrate. BACKGROUND

[0002] Chip packaging needs to be connected to the substrate by bonding wires in some cases, and the bonding wires are packaged together with the chip to the substrate. On the one hand, when the number of chip pins is large, in order to facilitate design, it is often necessary to set the signal pins in the inner circle and the power pins in the outer circle of the signal pins, so that the length of the signal arc is long. When the signal is high frequency, the long arc will greatly affect the S parameter of the signal and reduce the signal quality. In addition, the bonding wires connecting the signal pins are surrounded by a large number of power pins, and multiple layers of bonding wires often need to be staggered for wiring, so the wiring process is complex. On the other hand, since the bonding wire itself is relatively fragile, it must be packaged by molding, but when the chip power consumption is large, the conventional molding cannot meet the heat dissipation requirements: due to the arrangement of multiple layers of bonding wires, the bonding wires connected to the power supply or ground usually have large power consumption and large heat dissipation, which easily causes overheating of other nearby signal transmission bonding wires and thus causes the risk of melting, greatly limiting the application of wire bonding packaging. Therefore, a solution is needed to solve the problem of complex wire bonding process and poor heat dissipation of multi-layer bonding wire packaging. SUMMARY

[0003] The present application provides a chip packaging structure based on a flexible substrate to solve the problem of complex wire bonding process and poor heat dissipation of multi-layer bonding wire packaging.

[0004] The present application provides a packaging structure based on a flexible substrate, comprising: a flexible substrate; the flexible substrate is bent inward in a U shape at both ends, having a first part and a second part opposite to each other; the second part is provided with a plated through hole penetrating the flexible substrate in the thickness direction; the surface of the side of the second part facing away from the first part is provided with a first heat sink; a first chip; the first chip is arranged on the surface of the side of the first part facing the second part; the front surface of the first chip faces the second part; a second heat sink; the second heat sink is connected to the front surface of the first chip and connected to the first heat sink through the plated through hole.

[0005] Optionally, the second heat sink includes a heat sink main body and first and second connecting ends arranged at both ends of the heat sink main body, the first connecting end is connected to the power pins of the front surface of the chip, and the second connecting end is connected to one end of the plated through hole facing the first part; one end of the plated through hole facing away from the first part is connected to the first heat sink.

[0006] Optionally, the heat sink main body includes a metal column; the first connecting end includes a tin column or a tin disc; and the second connecting end includes a tin column or a tin disc.

[0007] Optionally, the first chip front surface is further provided with a signal pin, and the signal pin is electrically connected to the first part of the flexible substrate.

[0008] Optionally, the flexible substrate-based packaging structure further comprises a bonding wire, and the bonding wire connects the signal pin and the metal layer on the side surface of the first part of the flexible substrate facing the second part.

[0009] Optionally, the signal pin is arranged between the power pin and the edge of the first chip front surface in the position of the first chip front surface.

[0010] Optionally, the flexible substrate-based packaging structure further comprises a packaging layer, and the packaging layer is located between the first part and the second part and at least covers the first chip and the second heat sink.

[0011] Optionally, the flexible substrate-based packaging structure further comprises a third heat sink, and the third heat sink is arranged on the side surface of the second part facing the first part and is connected to the first heat sink through a plated through hole; the third heat sink is in contact with air.

[0012] Optionally, the packaging layer is provided with a heat dissipation groove with a communicating side on both sides of the region covering the second heat sink.

[0013] Optionally, the third heat sink is located in the heat dissipation groove.

[0014] The present application has the following advantages:

[0015] The flexible substrate-based packaging structure provided by the present application uses a flexible substrate, sets the flexible substrate in a form of U-shaped bending at both ends, sets the first chip between the first part and the second part of the flexible substrate parallel to each other (i.e. inside the opposite U-shaped part), and connects the first heat sink on the back surface of the second part (i.e. outside the opposite U-shaped part) through the second heat sink, thereby avoiding the use of multiple layers of bonding wires, and avoiding the risk of melting of adjacent bonding wires due to the large heat dissipation of the bonding wires connected to the ground or power supply. In addition, since the first heat sink on the back surface of the second part is used, the first heat sink can be a large-area heat sink, thereby greatly improving the heat dissipation efficiency and greatly improving the heat dissipation capacity of the packaging structure.

[0016] Further, through such a heat dissipation connection mode, the power pin can be arranged in the inner circle and connected to the first heat sink through the second heat sink, and the signal pin can be arranged in the outer circle and connected to the substrate through the bonding wire, thereby avoiding the arrangement of multiple layers of bonding wires, reducing the risk of melting on one hand, and simplifying the wire bonding process on the other hand.

[0017] Further, a third heat dissipation member is additionally arranged on the second part of the flexible substrate towards the first chip side, the third heat dissipation member is in contact with air, the area in contact with air is increased by the heat dissipation plate inside the flexible substrate, the circulation of air in the range surrounded by the flexible substrate is used to form convective heat exchange, and the heat dissipation effect is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application, and all other embodiments obtained by those skilled in the art without creative labor based on these drawings also belong to the protection scope of the present application.

[0019] Figure 1 A chip packaging structure based on a flexible substrate is provided for an embodiment of the present application.

[0020] Figures 2-4 A chip packaging structure based on a flexible substrate is provided for an embodiment of the present application.

[0021] Figure 5 A top perspective view of a chip packaging structure based on a flexible substrate is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0022] The present application provides a chip packaging structure based on a flexible substrate to solve the problems of complex wire bonding process and poor heat dissipation of multi-layer bonding wire packaging.

[0023] The present application provides a packaging structure based on a flexible substrate, comprising: a flexible substrate; the flexible substrate is bent in a U shape towards the inside of both ends, having a first part and a second part which are relatively parallel; the second part is provided with a plated through hole penetrating the flexible substrate in the thickness direction; the surface of the side of the second part away from the first part is provided with a first heat dissipation member; a first chip; the first chip is arranged on the surface of the side of the first part towards the second part; the front surface of the first chip faces the second part; a second heat dissipation member; the second heat dissipation member is connected to the front surface of the first chip and connected to the first heat dissipation member through the plated through hole.

[0024] The technical solutions of the present application will be described below in conjunction with the drawings, obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor also belong to the protection scope of the present application.

[0025] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0026] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0027] In addition, the technical features involved in the different embodiments of the application described below can be combined with each other as long as there is no conflict.

[0028] Embodiment

[0029] Reference Figures 1-4 The embodiment provides a flexible substrate-based packaging structure, comprising:

[0030] A flexible substrate 104; the flexible substrate 104 is inwardly bent in a U shape at both ends, having a first part and a second part which are relatively parallel; the second part is provided with a plated through hole penetrating the flexible substrate in the thickness direction; the surface of the side of the second part facing away from the first part is provided with a first heat dissipation member 101; the plated through hole is filled with a plated conductive material.

[0031] A first chip 107; the first chip 107 is arranged on the surface of the side of the first part facing the second part; the front surface of the first chip 107 faces the second part;

[0032] A second heat dissipation member; the second heat dissipation member is connected to the front surface of the first chip 107 and connected to the first heat dissipation member 101 through the plated through hole.

[0033] Further, in the embodiment, the second heat dissipation member comprises a heat dissipation body 105 and a connecting end 110 arranged at both ends of the heat dissipation body. The connecting end 110 comprises a first connecting end and a second connecting end, the first connecting end is connected to the power pin 108 on the front surface of the chip, and the second connecting end is connected to one end of the plated through hole facing the first part; one end of the plated through hole facing away from the first part is connected to the first heat dissipation member 101.

[0034] Specifically, the heat dissipation body 105 can be a metal column, for example, a copper column. The connecting end 110 can be a tin column or a tin disc or a tin block with a cross section in the shape of a Chinese character "N". For example, the first connecting end comprises a tin column or a tin disc; the second connecting end comprises a tin column or a tin disc. The first heat dissipation member 101 can be a heat dissipation plate, for example. Moreover, the first heat dissipation member 101 can span the back surfaces of the two separate second portions (as shown). Figure 1 In some other embodiments, the back surfaces of the two separate second portions are respectively provided with the first heat dissipation member 101.

[0035] Further, in the present embodiment, the second portion of the flexible substrate 104 is provided with a through hole penetrating the second portion from the thickness direction, and the second connecting end penetrates the through hole to connect the first heat dissipation member 101.

[0036] Further, in the present embodiment, the front surface of the first chip 107 is further provided with a signal pin 109, and the signal pin 109 is electrically connected to the first portion of the flexible substrate 104.

[0037] Further, in the present embodiment, the flexible substrate-based packaging structure further comprises a bonding wire 103, which connects the signal pin 109 and the metal layer on the side surface of the first portion of the flexible substrate 104 facing the second portion.

[0038] Further, in the present embodiment, the signal pin is arranged between the power pin 108 and the edge of the front surface of the first chip 107.

[0039] Further, the flexible substrate-based packaging structure further comprises:

[0040] a packaging layer 106; the packaging layer 106 is located between the first portion and the second portion, and the packaging layer 106 at least covers the first chip 107 and the second heat dissipation member.

[0041] In the present embodiment, the packaging structure of the flexible substrate 104 further comprises a third heat dissipation member 102; the third heat dissipation member 102 is arranged on the side surface of the second portion of the flexible substrate 104 facing the first portion, and is connected to the first heat dissipation member 101 through the through hole; the third heat dissipation member 102 is in contact with air.

[0042] Specifically, the packaging layer 106 is provided with a heat dissipation groove a with a communicating side on both sides of the region covering the second heat dissipation member, and the third heat dissipation member 102 is located in the heat dissipation groove a. The third heat dissipation member 102 can be a heat dissipation plate, for example. Referring to Figure 5 , Figure 5Fig. 4 is a perspective view of the encapsulation structure of the present embodiment. The first heat dissipation member 101 is hidden in the figure for the convenience of display. The x direction is the length direction and the y direction is the width direction. The encapsulation layer 106 has heat dissipation grooves a that are connected to the side, which means that the heat dissipation grooves a are connected to the ambient air in the width direction y, so that the heat dissipation grooves a are connected to the ambient air.

[0043] In addition, in the present embodiment, the encapsulation structure based on the flexible substrate further comprises metal balls 111 on the side of the first part of the flexible substrate 104 away from the first chip 107, which are used to realize the external connection of the encapsulation structure. The metal balls 111 can be tin balls, for example.

[0044] The encapsulation structure based on the flexible substrate provided by the present embodiment avoids the use of multi-layer bonding wires for wire bonding by using the flexible substrate 104, arranging the flexible substrate 104 in a U shape, arranging the first chip 107 between the first part and the second part of the flexible substrate 104 that are parallel to each other (i.e. inside the U shape), and connecting the first heat dissipation member on the back of the second part (i.e. outside the U shape) through the second heat dissipation member (including the heat dissipation body 105 and the connecting end 110), thereby avoiding the use of multi-layer bonding wires for wire bonding and avoiding the risk of melting of the adjacent bonding wires due to the large heat dissipation of the bonding wires connected to the ground or power supply. In addition, since the first heat dissipation member 101 on the back of the second part is used, the first heat dissipation member 101 can be a large-area heat dissipation plate, thereby greatly improving the heat dissipation efficiency and greatly improving the heat dissipation capacity of the encapsulation structure.

[0045] Further, through such a heat dissipation connection mode, the power supply pins 108 can be arranged in the inner circle and connected to the first heat dissipation member 101 through the second heat dissipation member, and the signal pins 109 can be arranged in the outer circle and connected to the flexible substrate 104 through the bonding wires 103, thereby avoiding the arrangement of multi-layer bonding wires, reducing the risk of melting on one hand, and simplifying the wire bonding process on the other hand, so that the wire bonding process is simple.

[0046] The encapsulation structure based on the flexible substrate of the present embodiment further comprises a third heat dissipation member 102 arranged on the side of the second part of the flexible substrate 104 facing the first chip 107, which is in contact with the air, thereby increasing the area of contact with the air inside the flexible substrate 104 through the heat dissipation plate, utilizing the circulation of air within the range surrounded by the flexible substrate 104 to form convective heat exchange, and further improving the heat dissipation effect.

[0047] In addition, by arranging through holes that penetrate the flexible substrate 104 in the thickness direction of the second part of the flexible substrate 104 and filling the through holes with electroplated materials, the current distribution through the flexible substrate 104 can be made more uniform through the large-area arrangement of the through holes, and the heat dissipation effect can be further improved.

[0048] Reference Figures 2-4The flexible substrate-based packaging structure can be manufactured through the following process flow.

[0049] Processing the flexible substrate: a flexible substrate 104 is provided, a metal layer (finger or pad) to be wired is arranged on a first part thereof, and a through hole is formed at a predetermined position on a second part.

[0050] Mounting the chip: the first chip 107 is fixed on the upper surface of the first part of the flexible substrate 104 through DA glue, and the signal pin 109 is connected to the metal layer on the surface of the substrate through the bonding wire 103.

[0051] Mounting the third heat-dissipating member: the third heat-dissipating member 102 is mounted on the predetermined position on the second part of the flexible substrate 104.

[0052] Plastic packaging: the first chip 107 on the flexible substrate 104 is plastic packaged with a packaging material to form a packaging layer 106, then the packaging layer 106 is punched above the position corresponding to the power pin 108 of the first chip and the second heat-dissipating member is arranged, the area where the plastic packaging layer covers the second heat-dissipating member is grooved on both sides to form a heat-dissipating groove communicating with the side parts.

[0053] Buckling the substrate: the second part of the flexible substrate 104 is turned to the upper surface of the packaging layer 106, the through hole on the surface layer of the flexible substrate 104 corresponds to the second heat-dissipating member one by one, then reflow is performed, so that the second part of the flexible substrate can be electrically connected to the power signal of the first chip 107 through the second heat-dissipating member on the side away from the first chip 107. The third heat-dissipating member falls into the space of the heat-dissipating groove.

[0054] Mounting the first heat-dissipating member: the first heat-dissipating member 101 is mounted on the surface of the second part of the flexible substrate 104 away from the first part, then the metal ball 111 is formed by ball mounting, and then reflow is performed.

[0055] The present application has been described by the above examples, and it is believed that those skilled in the art can understand the present application through the above examples. Obviously, the above examples are only examples for clearly illustrating, and do not limit the embodiments. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A flexible substrate-based package structure, characterized by, Comprising: a flexible substrate; the flexible substrate is inwardly bent in a U-shape at both ends, having a first portion and a second portion which are parallel to each other; the second portion is provided with a plated through hole which penetrates the flexible substrate in the thickness direction; the surface of the second portion which is opposite to the first portion is provided with a first heat dissipation member; a first chip; the first chip is arranged on the surface of the first portion which faces the second portion; the front surface of the first chip faces the second portion; a second heat dissipation member; the second heat dissipation member is connected to the front surface of the first chip and connected to the first heat dissipation member through the plated through hole; the second heat dissipation member comprises a heat dissipation body and a first connecting end and a second connecting end arranged at both ends of the heat dissipation body; the first connecting end is connected to the power pin of the front surface of the chip; the second connecting end is connected to one end of the plated through hole which faces the first portion; one end of the plated through hole which is opposite to the first portion is connected to the first heat dissipation member.

2. The flexible substrate-based packaging structure according to claim 1, wherein: the heat dissipation body comprises a metal column; the first connecting end comprises a tin column or a tin disc; the second connecting end comprises a tin column or a tin disc.

3. The flexible substrate-based packaging structure according to claim 1, wherein: the front surface of the first chip is further provided with a signal pin; the signal pin is electrically connected to the first portion of the flexible substrate.

4. The flexible substrate-based packaging structure according to claim 3, wherein: further comprising a bonding wire; the bonding wire connects the signal pin and a metal layer on the surface of the first portion of the flexible substrate which faces the second portion.

5. The flexible substrate-based packaging structure according to claim 4, wherein: the signal pin is arranged between the power pin and the edge of the front surface of the first chip.

6. The flexible substrate-based package structure of claim 5, wherein, Further comprising: a packaging layer; the packaging layer is located between the first portion and the second portion; the packaging layer at least covers the first chip and the second heat dissipation member.

7. The flexible substrate-based package structure of claim 6, wherein, Further comprising: a third heat dissipation member; the third heat dissipation member is arranged on the surface of the second portion which faces the first portion and connected to the first heat dissipation member through the plated through hole; the third heat dissipation member is in contact with air.

8. The flexible substrate-based package structure of claim 7, wherein, the packaging layer is provided with a heat dissipation groove with a communicating side on both sides of the area which covers the second heat dissipation member.

9. The flexible substrate-based package structure of claim 8, wherein, the third heat dissipation member is located in the heat dissipation groove.

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