A BGA chip packaging structure and packaging process thereof

Abstract

The invention discloses a BGA chip packaging structure and a packaging process thereof, and relates to the technical field of chip packaging, comprising a substrate, a chip unit, a conductive part, a solder ball, a bonding wire and a heat dissipation column, wherein a plurality of through holes are provided on the substrate; the chip unit is mounted on the upper end of the substrate; the structure comprises an upper supporting unit arranged at the upper end of the substrate, a lower supporting unit arranged at the lower end of the substrate, a conductive unit placed inside the upper supporting unit and the lower supporting unit, an upper pad arranged inside the upper supporting unit and a lower pad arranged inside the lower supporting unit; the solder ball is arranged inside the lower supporting unit; the upper pad arranged outside the chip unit is electrically connected to the chip unit through the bonding wire; the heat dissipation column is arranged at the upper end of the upper supporting unit, and a groove for the bonding wire to pass through is provided at the lower end of the heat dissipation column; the invention can block the combination of different molten solder balls and the overlap between different bonding wires, and finally achieve the purpose of reducing the risk of short circuit.

Description

Technical Field

[0001] The present invention relates to the technical field related to chip packaging, and in particular to a BGA chip packaging structure and a packaging process thereof. Background Art

[0002] Package refers to the shell used to install semiconductor integrated circuit chips. It not only plays the role of placing, fixing, sealing, protecting chips and enhancing thermal conductivity, but also serves as a bridge between the internal world of the chip and the external circuit - the contacts on the chip are connected to the pins of the package shell with wires, and these pins are connected to other devices through wires on the printed circuit board. BGA (Ball Grid Array) packaging technology is a high-density surface mounting packaging technology. At the bottom of the package, the pins are spherical and arranged in a grid-like pattern. BGA packaging can greatly increase the number of I / Os of the device, reduce the size of the package body, and save assembly space, and has been widely used.

[0003] In the surface mount production process, since the solder balls will be in a molten state under high temperature, there will be a phenomenon of flow overlap between two adjacent solder balls in the molten state. After the two adjacent solder balls combine, it will cause a short circuit on the circuit board. In addition, bonding wires are required to connect the chip to some pads. When there are a large number of bonding wires, the bonding wires are prone to overlap, which will lead to a short circuit. Summary of the invention

[0004] In order to solve the defects in the prior art, the present invention provides a BGA chip packaging structure and a packaging process thereof.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] The present invention provides a BGA chip packaging structure, comprising:

[0007] A substrate, wherein a plurality of through holes are formed on the substrate;

[0008] A chip unit is mounted on the upper end of the substrate;

[0009] A conductive part is arranged inside the through hole, comprising an upper supporting unit arranged at the upper end of the substrate, a lower supporting unit arranged at the lower end of the substrate, a conductive unit placed inside the upper supporting unit and the lower supporting unit, an upper pad arranged inside the upper supporting unit, and a lower pad arranged inside the lower supporting unit;

[0010] A solder ball disposed inside the lower support unit;

[0011] The upper pad disposed outside the chip unit is electrically connected to the chip unit via a bonding wire;

[0012] A heat dissipation column is arranged at the upper end of the upper support unit, and a groove for the bonding wire to pass through is opened at the lower end of the heat dissipation column.

[0013] As a preferred technical solution of the present invention, the upper support unit and the lower support unit are both hollow structures;

[0014] The upper support unit includes an upper vertical portion and an upper boss portion which are integrally formed, and the lower support unit includes a lower vertical portion and a lower boss portion which are integrally formed.

[0015] As a preferred technical solution of the present invention, an upper end of the upper boss portion is provided with an upper placement groove at a position corresponding to the upper solder pad, and an upper end of the lower boss portion is provided with a lower placement groove at a position corresponding to the lower solder pad, and the upper boss portion and the lower boss portion are respectively provided with limiting protrusions at positions corresponding to the conductive unit.

[0016] As a preferred technical solution of the present invention, the upper placement groove is flat, and the cross-section of the lower placement groove is arc-shaped.

[0017] As a preferred technical solution of the present invention, the heat dissipation column is a hollow structure, and the lower end of the heat dissipation column covers the upper soldering pad inside the heat dissipation column.

[0018] As a preferred technical solution of the present invention, a filling glue layer is further provided between the chip and the substrate, and the filling glue layer is coated on the outer side of the chip unit.

[0019] As a preferred technical solution of the present invention, a packaging cover is fixedly provided on the upper end of the substrate, the gap between the packaging cover and the substrate is filled with epoxy resin, and a heat sink is provided between the filling glue layer and the packaging cover.

[0020] As a preferred technical solution of the present invention, the packaging cover plate is provided with a heat sink at a position corresponding to the heat sink, and the heat sink is arranged in close contact with the heat sink.

[0021] The present invention also provides a packaging process for a BGA chip packaging structure, comprising the following steps:

[0022] S1: providing a substrate, and forming a plurality of through holes on the substrate;

[0023] S2: placing the upper support unit inside the through hole, and mounting the chip unit on the substrate so that the upper pad is placed inside the upper placement groove;

[0024] S3: Install the heat dissipation column on the upper end of the upper support unit, and pass the bonding wire through the groove on the heat dissipation column so that the other end of the bonding wire is welded to the upper pad;

[0025] S4: completing the packaging of the packaging cover plate, and filling the gap between the packaging cover plate and the substrate with epoxy resin;

[0026] S5: Inverting the substrate after the preliminary packaging, placing the conductive unit inside the upper supporting unit, and then placing the lower supporting unit inside the through hole;

[0027] S6: Complete the welding between the solder ball and the lower pad.

[0028] As a preferred technical solution of the present invention, before performing step S4, a filling glue layer is firstly provided between the chip and the substrate, and after the filling glue layer is cured, a heat sink is placed on the upper end of the chip unit.

[0029] The beneficial effects of the present invention are:

[0030] 1. In the present invention, by providing a lower support unit and placing the solder ball inside the lower support unit, the lower support unit can block the combination of molten solder balls between different pads, thereby ultimately achieving the purpose of reducing the risk of short circuit.

[0031] 2. In the present invention, a heat dissipation column is provided and a groove is opened on the heat dissipation column. When the bonding wire is welded to the pad on the substrate, it can pass through the groove on the heat dissipation column and be welded to the pad. In this way, a heat dissipation column is provided on the outside of each bonding wire to protect the bonding wire, thereby effectively avoiding overlapping between the bonding wires and further reducing the risk of short circuit.

[0032] 3. In the present invention, a heat dissipation column is provided in combination with a heat sink. On the one hand, the heat dissipation column can protect the bonding wire. On the other hand, the setting of the heat dissipation column can quickly dissipate the heat inside the chip to the heat sink through the heat dissipation column, thereby ensuring the heat dissipation effect inside the chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 It is a schematic diagram of the overall structure of the BGA chip packaging structure.

[0035] Figure 2 for Figure 1 A magnified schematic diagram of center A.

[0036] Figure 3 It is a schematic diagram of the structure of the conductive part.

[0037] Figure 4 It is a partial schematic diagram of the conductive part.

[0038] Figure 5 It is a schematic diagram of the structure of the heat dissipation column.

[0039] Figure 6 This is a flow chart of the BGA chip packaging process.

[0040] In the figure: 1, substrate; 11, through hole; 2, chip unit; 3, conductive part; 31, upper support unit; 311, upper vertical part; 312, upper boss part; 3121, upper placement groove; 3122, limiting bump; 32, lower support unit; 321, lower vertical part; 322, lower boss part; 3221, lower placement groove; 33, conductive unit; 34, upper pad; 35, lower pad; 4, solder ball; 5, bonding wire; 6, heat dissipation column; 61, groove; 7, filling glue layer; 8, packaging cover; 81, heat sink; 9, heat sink. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0042] Embodiment 1

[0043] like Figure 1-Figure 5 As shown, a BGA chip packaging structure includes a substrate 1, a chip unit 2, a conductive part 3, a solder ball 4, a bonding wire 5 and a heat dissipation column 6, wherein the substrate 1 is provided with a plurality of through holes 11; the chip unit 2 is mounted on the upper end of the substrate 1; the conductive part 3 is arranged inside the through hole 11, and includes an upper support unit 31 arranged at the upper end of the substrate 1, a lower support unit 32 arranged at the lower end of the substrate 1, a conductive unit 33 placed inside the upper support unit 31 and the lower support unit 32, an upper pad 34 arranged inside the upper support unit 31, and a lower pad 35 arranged inside the lower support unit 32; the solder ball 4 is arranged inside the lower support unit 32; the upper pad 34 arranged on the outer side of the chip unit 2 is electrically connected to the chip unit 2 through the bonding wire 5; the heat dissipation column 6 is arranged at the upper end of the upper support unit 31, and the lower end of the heat dissipation column 6 is provided with a groove 61 for the bonding wire 5 to pass through.

[0044] Among them, by providing the lower support unit 32 and placing the solder ball 4 inside the lower support unit 32, the solder ball 4 can reduce the possibility of lateral flow even in the molten state due to the limiting effect of the lower support unit 32. Therefore, the lower support unit 32 can block the combination of the molten solder ball 4 between different pads, and finally achieve the purpose of reducing the risk of short circuit;

[0045] By setting up a heat dissipation column 6 and opening a groove 61 on the heat dissipation column 6, the bonding wire 5 can pass through the groove 61 on the heat dissipation column 6 and be welded to the pad on the substrate 1. In this way, a heat dissipation column 6 is set on the outside of each bonding wire 5 to protect the bonding wire 5, thereby effectively avoiding overlapping between the bonding wires 5 and further reducing the risk of short circuit.

[0046] After being inserted into the through hole 11, the upper support unit 31 and the lower support unit 32 need to be fixed to the inner wall of the through hole 11. Optionally, the upper support unit 31 and the lower support unit 32 are fixed to the inside of the through hole 11 by bonding. In addition, the heat dissipation column 6 can also be fixed to the upper end of the upper support unit 31 by bonding, or by welding.

[0047] It should be noted that the solder balls 4 are made of tin-bismuth based solder, and the distance between the center of each solder ball 4 and the center of an adjacent solder ball 4 is not less than 0.5 mm.

[0048] Further, if Figure 2-Figure 4 As shown, the upper support unit 31 and the lower support unit 32 are both hollow structures;

[0049] The upper support unit 31 includes an upper vertical portion 311 and an upper boss portion 312 formed in one piece, and the lower support unit 32 includes a lower vertical portion 321 and a lower boss portion 322 formed in one piece.

[0050] An upper placement groove 3121 is formed at the upper end of the upper boss portion 312 at a position corresponding to the upper solder pad 34, a lower placement groove 3221 is formed at the upper end of the lower boss portion 322 at a position corresponding to the lower solder pad 35, and limiting protrusions 3122 are respectively provided on the upper boss portion 312 and the lower boss portion 322 at positions corresponding to the conductive unit 33.

[0051] Among them, by respectively providing an upper vertical portion 311 and a lower vertical portion 321 on the upper supporting unit 31 and the lower supporting unit 32, after the upper supporting unit 31 and the lower supporting unit 32 are installed inside the through hole 11, the cavity formed by the upper vertical portion 311 and the lower vertical portion 321 cooperate with each other can be used to place the conductive unit 33, and the conductive unit 33 will be subsequently welded to the upper pad 34 and the lower pad 35, respectively, so as to realize the electrical connection between the chip unit 2 and the solder ball 4;

[0052] In addition, an upper boss portion 312 and a lower boss portion 322 are respectively provided on the upper support unit 31 and the lower support unit 32. The upper boss portion 312 can be used to install the upper solder pad 34 on the one hand, and can be used to fix the heat dissipation column 6 on the other hand. It should be noted that in order to ensure the flatness of the upper end of the substrate 1 and the subsequent welding effect, a blind hole coaxial with the through hole 11 needs to be opened at the position of the substrate 1 corresponding to the upper boss portion 312. After the upper boss portion 312 is placed inside the blind hole, the upper surface of the upper boss portion 312 needs to be lower than the upper surface of the substrate 1. Preferably, the upper surface of the upper boss portion 312 is flush with the upper surface of the substrate 1, and then an upper placement groove 3121 for placing the upper solder pad 34 is opened at the upper end of the upper boss portion 312.

[0053] Similarly, the lower boss portion 322 can be used to install the lower pad 35 on the one hand, and on the other hand, the lower boss portion 322 is mainly used to receive the solder ball 4 . Therefore, the main component for blocking the flow of the molten solder ball 4 is the lower boss portion 322 .

[0054] It should be noted that the upper placement groove 3121 is flat, and the cross-section of the lower placement groove 3221 is arc-shaped.

[0055] Further, if Figure 1 As shown, a filling glue layer 7 is further provided between the chip and the substrate 1, and the filling glue layer 7 is coated on the outside of the chip unit 2;

[0056] A packaging cover plate 8 is fixedly disposed on the upper end of the substrate 1 , a gap between the packaging cover plate 8 and the substrate 1 is filled with epoxy resin, and a heat sink 9 is disposed between the filling glue layer 7 and the packaging cover plate 8 .

[0057] The filling glue layer 7 is coated on the outside of the welding structure at the lower end of the chip unit 2 to protect the welding part and prevent heat from directly invading the welding structure and affecting the performance of the chip unit 2. In addition, the creeping height of the filling glue layer 7 is controlled between 50%-80% of the thickness of the chip unit 2, so that the filling glue layer 7 can be completely filled between the chip unit 2 and the substrate 1 and the lower edge of the chip unit 2 is coated therein, thereby further enhancing the protection effect of the welding structure at the bottom of the chip unit 2.

[0058] In detail, the heat sink 9 is formed by stacking multiple layers of sheet materials. Optionally, the heat sink 9 is made of copper or aluminum alloy. In the present embodiment, the thickness of the heat sink 9 is 1 mm-3 mm.

[0059] In this embodiment, the package cover plate 8 is made of a metal with excellent thermal conductivity, such as an aluminum metal plate or a copper metal plate. The aluminum metal plate or the copper metal plate has the properties of being light, conductive, and heat-conductive, which helps to dissipate heat from the chip unit 2 and improves the service life.

[0060] Further, if Figure 5 As shown, the heat dissipation column 6 is a hollow structure, and the lower end of the heat dissipation column 6 covers the upper solder pad 34 inside the heat dissipation column 6; the packaging cover plate 8 is provided with a heat dissipation fin 81 at a position corresponding to the heat dissipation column 6, and the heat dissipation column 6 is arranged in close contact with the heat dissipation fin 81.

[0061] Among them, by setting the heat dissipation column 6 in conjunction with the heat sink 81, the heat dissipation column 6 can protect the bonding wire 5 on the one hand, and on the other hand, the setting of the heat dissipation column 6 can quickly dissipate the heat inside the chip to the heat sink 81 through the heat dissipation column 6, thereby ensuring the heat dissipation effect inside the chip. In addition, considering that the heat dissipation column 6 is arranged between the packaging cover plate 8 and the substrate 1, after filling and sealing with epoxy resin, the setting of multiple groups of heat dissipation columns 6 can also effectively improve the overall structural strength of the chip, thereby improving the service life of the chip.

[0062] Optionally, the heat sink 6 is made of a metal with excellent thermal conductivity, such as aluminum or copper, and the heat sink 81 can be made of indium or indium-silver alloy.

[0063] It should be noted that when epoxy resin is used for packaging, since a groove 61 is provided at the lower end of the heat dissipation column 6, epoxy resin will also be injected into the heat dissipation column 6 after packaging to ensure the structural stability of the bonding wire 5 and the bonding point.

[0064] Embodiment 2

[0065] The components that are the same or corresponding to those in the first embodiment are marked with the same reference numerals as those in the first embodiment. For the sake of simplicity, only the differences from the first embodiment are described below. The second embodiment differs from the first embodiment in that:

[0066] like Figure 6 As shown, the present invention also provides a BGA chip packaging process, comprising the following steps:

[0067] S1: providing a substrate 1, and forming a plurality of through holes 11 on the substrate 1;

[0068] The substrate 1 in this embodiment is made of PP (polypropylene), polyimide, polyester or the like. Of course, other conventional substrate 1 materials may also be used, which are not listed here one by one. The opening of the through hole 11 needs to be compatible with the upper support unit 31 and the lower support unit 32.

[0069] S2: placing the upper support unit 31 inside the through hole 11, and mounting the chip unit 2 on the substrate 1 so that the upper pad 34 is placed inside the upper placement groove 3121;

[0070] Before placing the upper support unit 31, glue needs to be applied on the outer side of the upper support unit 31 to achieve a stable connection between the upper support unit 31 and the through hole 11. After completing the placement of the upper pad 34, flux can be applied on the upper pad 34 before reflow soldering.

[0071] S3: Install the heat dissipation column 6 on the upper end of the upper support unit 31, and pass the bonding wire 5 through the groove 61 on the heat dissipation column 6 so that the other end of the bonding wire 5 is welded to the upper pad 34;

[0072] S4: completing the packaging of the packaging cover plate 8 and filling the gap between the packaging cover plate 8 and the substrate 1 with epoxy resin;

[0073] S5: Invert the substrate 1 after the preliminary packaging, place the conductive unit 33 inside the upper support unit 31, and then place the lower support unit 32 inside the through hole 11;

[0074] At the same time, the lower pad 35 needs to be placed inside the lower support unit 32. At this time, the conductive unit 33 is overlapped with the upper pad 34 and the lower pad 35 respectively, and then reflow soldering is used to solder them.

[0075] S6: The soldering between the solder ball 4 and the lower pad 35 is completed.

[0076] It should be noted that before performing step S4 , a filling glue layer 7 is firstly provided between the chip and the substrate 1 , and after the filling glue layer 7 is cured, a heat sink 9 is placed on the upper end of the chip unit 2 .

[0077] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A BGA chip packaging structure, It is characterized in that include: A substrate (1), wherein the substrate (1) is provided with a plurality of groups of through holes (11); A chip unit (2) mounted on the upper end of the substrate (1); A conductive portion (3) arranged inside the through hole (11), comprising an upper support unit (31) arranged at the upper end of the substrate (1), a lower support unit (32) arranged at the lower end of the substrate (1), a conductive unit (33) placed inside the upper support unit (31) and the lower support unit (32), an upper pad (34) arranged inside the upper support unit (31), and a lower pad (35) arranged inside the lower support unit (32); A solder ball (4) arranged inside the lower support unit (32); The upper pad (34) arranged outside the chip unit (2) is electrically connected to the chip unit (2) via a bonding wire (5); A heat dissipation column (6) is arranged at the upper end of the upper support unit (31), and a groove (61) for the bonding wire (5) to pass through is formed at the lower end of the heat dissipation column (6); The upper support unit (31) comprises an upper vertical portion (311) and an upper boss portion (312) which are integrally formed; The lower support unit (32) comprises an integrally formed lower vertical portion (321) and a lower boss portion (322); The upper end of the lower boss portion (322) is provided with a lower placement groove (3221) at a position corresponding to the lower pad (35), and the upper boss portion (312) and the lower boss portion (322) are respectively provided with a limiting bump (3122) at a position corresponding to the conductive unit (33); The cross section of the lower placement groove (3221) is arc-shaped.

2. A BGA chip packaging structure according to claim 1, It is characterized in that The upper support unit (31) and the lower support unit (32) are both hollow structures.

3. A BGA chip packaging structure according to claim 2, It is characterized in that An upper placement groove (3121) is provided at the upper end of the upper boss portion (312) at a position corresponding to the upper solder pad (34).

4. A BGA chip packaging structure according to claim 3, It is characterized in that The upper placement groove (3121) is flat.

5. The BGA chip packaging structure according to claim 1, It is characterized in that The heat dissipation column (6) is a hollow structure, and the lower end of the heat dissipation column (6) covers the upper soldering pad (34) inside the heat dissipation column (6).

6. The BGA chip packaging structure according to claim 1, It is characterized in that A filling glue layer (7) is also provided between the chip and the substrate (1), and the filling glue layer (7) is coated on the outside of the chip unit (2).

7. A BGA chip packaging structure according to claim 6, It is characterized in that A packaging cover plate (8) is fixedly arranged on the upper end of the substrate (1), a gap between the packaging cover plate (8) and the substrate (1) is filled with epoxy resin, and a heat sink (9) is arranged between the filling glue layer (7) and the packaging cover plate (8).

8. A BGA chip packaging structure according to claim 7, It is characterized in that The packaging cover plate (8) is provided with a heat sink (81) at a position corresponding to the heat sink column (6), and the heat sink column (6) and the heat sink (81) are arranged in close contact.

9. A packaging process for a BGA chip packaging structure according to any one of claims 1 to 8, It is characterized in that The following steps are involved: S1: providing a substrate (1), and providing a plurality of groups of through holes (11) on the substrate (1); S2: placing the upper support unit (31) inside the through hole (11), and mounting the chip unit (2) on the substrate (1) so that the upper pad (34) is placed inside the upper placement groove (3121); S3: installing the heat dissipation column (6) on the upper end of the upper support unit (31), and passing the bonding wire (5) through the groove (61) on the heat dissipation column (6) so that the other end of the bonding wire (5) is welded to the upper pad (34); S4: completing the packaging of the packaging cover plate (8), and filling the gap between the packaging cover plate (8) and the substrate (1) with epoxy resin; S5: inverting the substrate (1) after the preliminary packaging, placing the conductive unit (33) inside the upper support unit (31), and then placing the lower support unit (32) inside the through hole (11); S6: completing the welding between the solder ball (4) and the lower solder pad (35).

10. The packaging process according to claim 9, It is characterized in that Before performing step S4, a filling glue layer (7) is first arranged between the chip and the substrate (1), and after the filling glue layer (7) is solidified, a heat sink (9) is placed on the upper end of the chip unit (2).

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