Millimeter wave radio frequency chip ball grid array (BGA) packaging tube shell

Abstract

The utility model belongs to the technical field of semiconductor packaging, and discloses a millimeter wave radio frequency chip BGA packaging tube shell, which comprises a ceramic base, a kovar enclosure frame, a cover plate and a BGA ball, a first metal coating is plated on the upper surface of the ceramic base, a second metal coating is plated on the lower surface of the ceramic base, a top layer bonding pad is etched on the periphery of the first metal coating, a bottom layer ball mounting pad is etched on the periphery of the second metal coating, and the top layer bonding pad and the bottom layer ball mounting pad are arranged in a one-to-one correspondence mode; the ceramic pedestal is provided with a through hole, and the through hole is internally provided with a copper column which is used for connecting the corresponding top layer bonding pad and bottom layer ball mounting pad. The kovar enclosure frame is fixedly arranged on the peripheral edge of the upper surface of the first metal coating, and the cover plate is packaged on the top of the kovar enclosure frame. According to the utility model, the isolation between the radio frequency interfaces is improved, the heat dissipation requirement of the chip is met, and the use cost of the product and the process assembly difficulty are reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of semiconductor packaging, and relates to a millimeter wave radio frequency chip BGA packaging tube shell. Background Art

[0002] Microelectronics packaging is the process of reliably mounting semiconductor integrated circuit chips onto a certain housing. After the chip on the printed circuit board is packaged, the packaged housing has the functions of fixing, sealing, protecting the chip, and connecting internal and external circuits. Printed circuit boards can be widely used in radio systems, including battlefield identification, communications, radar and guidance in the military, as well as 5G communication equipment and automotive anti-collision radar equipment in the civilian sector.

[0003] In existing technology, millimeter-wave RF chips are typically packaged within a metal cavity. However, due to the discontinuous transmission path of the millimeter-wave RF chip's RF signal, the transmitted signal generates spatial radiation at the input side of the millimeter-wave RF chip. The radiated electromagnetic signal then propagates through the metal cavity to the chip's output side. Therefore, when applied to millimeter-wave RF chips, existing packaging methods have poor spatial isolation performance, affecting the RF performance of millimeter-wave devices. Utility Model Content

[0004] The purpose of the utility model is to provide a millimeter wave radio frequency chip BGA packaging tube shell, aiming to solve the problem of poor spatial isolation performance of the existing millimeter wave radio frequency chip packaging method.

[0005] In order to achieve the above-mentioned purpose, the technical solutions adopted by the present invention are as follows:

[0006] A millimeter wave radio frequency chip BGA packaging tube shell, comprising a ceramic base, a Kovar frame, a cover plate and a BGA ball;

[0007] The upper surface of the ceramic base is plated with a first metal coating, and the lower surface of the ceramic base is plated with a second metal coating. Top-layer bonding pads are etched around the first metal coating, and bottom-layer ball-planting pads are etched around the second metal coating. The top-layer bonding pads and the bottom-layer ball-planting pads are respectively arranged in a one-to-one correspondence. The ceramic base is provided with a through hole, and a copper column is provided in the through hole for connecting the corresponding top-layer bonding pad and the bottom-layer ball-planting pad;

[0008] The Kovar frame is fixed at the edges of the upper surface of the first metal coating, the cover plate is encapsulated on the top of the Kovar frame, a chip cavity is opened in the middle of the first metal coating and passes through the first metal coating for installing a millimeter wave RF chip, isolation copper pillars are provided around the upper surface of the first metal coating, the upper end of the isolation copper pillar does not contact the lower surface of the cover plate, and the distance between the upper end of the isolation copper pillar and the lower surface of the cover plate is less than 0.1mm; the lower surface of the second metal coating is provided with a solder resist layer, and the BGA ball is welded to the lower surface of the solder resist layer.

[0009] As a limitation, the horizontal and vertical spacings of the BGA balls are both 0.8 mm.

[0010] As a second limitation, a circle of solder resist area is provided on the upper surface of the first metal plating layer close to the inner side of the kovar frame.

[0011] As a third limitation, the thickness of the first metal plating layer is 0.2 mm, and the height of the isolated copper pillar is 0.8 mm.

[0012] As a fourth limitation, the BGA balls form twelve radio frequency interfaces and twelve low frequency interfaces.

[0013] As the present invention adopts the above technical solution, compared with the prior art, the technical progress achieved is:

[0014] (1) The present invention forms a packaging cavity for packaging a millimeter wave radio frequency chip by enclosing a ceramic base, a Kovar frame and a cover plate. A chip cavity groove is provided through the middle of the first metal plating layer to install and fix the chip. The internal space of the packaging cavity can be divided by providing isolation copper pillars, which significantly improves the isolation between radio frequency interfaces, reduces crosstalk and coupling between radio frequency channels, and can better exert the performance of the millimeter wave radio frequency chip.

[0015] (2) The thickness of the first metal coating in the present invention is 0.2 mm, that is, the thickness of the chip cavity is also 0.2 mm, which can be used to install millimeter wave radio frequency chips with a thickness greater than 0.3 mm. The use of this structure can reduce the height difference between the chip and the peripheral devices and the top bonding pad on the upper surface of the ceramic base, reduce the length of the bonding wire, and avoid the process operation difficulties caused by the large height difference of the bonding wire and the influence of the introduced parasitic parameters on the radio frequency energy;

[0016] (3) The present invention provides a chip cavity that penetrates the first metal plating layer. After the millimeter wave radio frequency chip is fixedly installed in the chip cavity, the chip contacts the ceramic base, thereby meeting the heat dissipation requirements of the chip itself;

[0017] (4) The utility model adopts BGA ball technology, which has lower requirements for peripheral circuit board design and processing, while optimizing performance, reducing product use costs and reducing process assembly difficulty;

[0018] (5) The utility model forms isolation by isolating copper pillars around the RF interface, and opens a chip cavity in the middle of the first metal plating layer to install the chip. By changing the size of the packaging cavity enclosed by the ceramic base, the ferrite frame and the cover plate to avoid the resonance frequency of the packaging cavity affecting the chip operating frequency, the problem of cavity resonance of the millimeter wave RF chip is solved.

[0019] In summary, the present invention improves the isolation between radio frequency interfaces, meets the heat dissipation requirements of the chip itself, and reduces product use costs and process assembly difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Shown is a front structural schematic diagram of an embodiment of the present utility model;

[0021] Figure 2 Shown is an embodiment of the present utility model Figure 1 Schematic diagram of the cross-sectional structure of the AA surface;

[0022] Figure 3 Shown is a schematic structural diagram of the upper surface of the ceramic base according to an embodiment of the present invention;

[0023] Figure 4 Shown is a schematic structural diagram of the lower surface of the ceramic base according to an embodiment of the present invention;

[0024] Figure 5 Shown is a schematic diagram of a radio frequency interface and a low frequency interface according to an embodiment of the present utility model;

[0025] Figure 6 The figure shows the simulation result of the isolation between radio frequency interfaces according to an embodiment of the present invention;

[0026] In the figure: 1. Ceramic base; 2. Kovar frame; 3. Cover; 4. BGA ball; 5. First metal plating layer; 6. Second metal plating layer; 7. Top bonding pad; 8. Bottom ball planting pad; 9. Solder mask area; 10. Chip cavity; 11. Isolation copper pillar; 12. Solder mask layer; 13. RF interface; 14. Low frequency interface. DETAILED DESCRIPTION

[0027] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation methods in conjunction with the accompanying drawings.

[0028] Embodiment A millimeter wave radio frequency chip BGA package shell

[0029] like Figure 1 As shown, this embodiment is a millimeter wave radio frequency chip BGA package tube shell, including a ceramic base 1, a Kovar frame 2, a cover plate 3 and a BGA ball 4; wherein the ceramic base 1 is made of LTCC, and the Kovar frame 2 and the cover plate 3 are both made of Kovar alloy.

[0030] like Figures 2 to 4As shown, the upper surface of the ceramic base 1 is plated with a first metal coating 5, the thickness of the first metal coating 5 is 0.2 mm, and the lower surface of the ceramic base 1 is plated with a second metal coating 6; wherein the first metal coating 5 is etched with a top bonding pad 7 around the first metal coating 5, and the top bonding pad 7 is set through the first metal coating 5, and the second metal coating 6 is etched with a bottom ball planting pad 8 around the second metal coating 6, and the bottom ball planting pad 8 is set through the second metal coating 6, and the top bonding pad 7 and the bottom ball planting pad 8 are respectively arranged in a one-to-one correspondence; a through hole is provided on the ceramic base 1, and a copper column is provided in the through hole for connecting the corresponding top bonding pad 7 and the bottom ball planting pad 8.

[0031] In this embodiment, the kovable frame 2 is fixedly mounted on the edges of the upper surface of the first metal coating 5, the cover plate 3 is encapsulated on the top of the kovable frame 2, and a circle of solder resist area 9 is provided on the upper surface of the first metal coating 5 near the inner side of the kovable frame 2. The solder resist area 9 can prevent the solder from flowing into the inner surface of the upper surface of the ceramic base 1 when soldering the kovable frame 2.

[0032] A chip cavity 10 for installing a millimeter-wave RF chip is provided in the middle of the first metal coating 5. Since the thickness of the first metal coating 5 is 0.2 mm, the height of the chip cavity 10 is also 0.2 mm. The chip cavity 10 can be used to install a millimeter-wave RF chip with a thickness greater than 0.3 mm. The use of this structure can reduce the height difference between the chip and the peripheral devices and the top bonding pad 7 on the upper surface of the ceramic base 1, reduce the length of the bonding wire, and avoid the process operation difficulties caused by the excessive height difference of the bonding wire and the influence of the introduced parasitic parameters on the RF performance.

[0033] Isolation copper pillars 11 are provided around the upper surface of the first metal plating layer 5, and the isolation copper pillars 11 are distributed in parallel on both sides of the top bonding pad 7 to realize the radiation of the radio frequency interface signal in the packaging cavity formed by the ceramic base 1, the kovar frame 2 and the cover plate 3, and reduce the influence of the radio frequency interface on the radio frequency signal interference in the packaging cavity. The height of the isolation copper pillar 11 is 0.8 mm, the upper end of the isolation copper pillar 11 does not contact the lower surface of the cover plate 3, and the distance between the upper end of the isolation copper pillar 11 and the lower surface of the cover plate 3 is less than 0.1 mm; the number and spacing of the isolation copper pillars 11 can be specifically set according to the frequency of use. In this embodiment, the isolation copper pillars 11 are arranged close to the top bonding pad 7 and distributed on both sides of the top bonding pad 7.

[0034] In this embodiment, the lower surface of the second metal plating layer 6 is provided with a solder resist layer 12, and BGA balls 4 are soldered on the solder resist layer 12. The horizontal and vertical spacings of the BGA balls 4 are both 0.8 mm. The BGA balls 4 form twelve RF interfaces 13 and twelve low-frequency interfaces 14. Figure 5 shown.

[0035] During packaging in this embodiment, the millimeter wave RF chip is first mounted and fixed in the chip cavity 10 , and then after the chip and peripheral circuits are assembled, the cover plate 3 is sealed on the top of the Kovar frame 2 using parallel seam welding.

[0036] like Figure 6 The figure shows the simulation results of the isolation between adjacent RF interfaces in this embodiment. According to the simulation results, in this embodiment, within the simulation range of the DC-50GHz frequency band, the isolation between RF interfaces is >60dB. This result meets the working requirements of millimeter-wave RF chips, and can avoid the influence of the packaging cavity on chip indicators during RF chip packaging testing, which is conducive to promoting the application and promotion of RF chips, especially millimeter-wave RF chips.

[0037] It should be noted that the above description is merely 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 above embodiments, those skilled in the art may still modify the technical solutions described in the above embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A millimeter wave radio frequency chip BGA packaging tube shell, characterized in that: Including ceramic base, Kovar frame, cover and BGA ball; The upper surface of the ceramic base is plated with a first metal coating, and the lower surface of the ceramic base is plated with a second metal coating. Top-layer bonding pads are etched around the first metal coating, and bottom-layer ball-planting pads are etched around the second metal coating. The top-layer bonding pads and the bottom-layer ball-planting pads are respectively arranged in a one-to-one correspondence. The ceramic base is provided with a through hole, and a copper column is provided in the through hole for connecting the corresponding top-layer bonding pad and the bottom-layer ball-planting pad; The Kovar frame is fixed at the edges of the upper surface of the first metal coating, the cover plate is encapsulated on the top of the Kovar frame, a chip cavity is opened in the middle of the first metal coating and passes through the first metal coating for installing a millimeter wave RF chip, isolation copper pillars are provided around the upper surface of the first metal coating, the upper end of the isolation copper pillar does not contact the lower surface of the cover plate, and the distance between the upper end of the isolation copper pillar and the lower surface of the cover plate is less than 0.1mm; the lower surface of the second metal coating is provided with a solder resist layer, and the BGA ball is welded to the lower surface of the solder resist layer.

2. The millimeter wave radio frequency chip BGA package tube shell according to claim 1, characterized in that: The horizontal and vertical spacings of the BGA balls are both 0.8 mm.

3. The millimeter wave radio frequency chip BGA package tube shell according to claim 1, characterized in that: A circle of solder resist area is provided on the upper surface of the first metal plating layer close to the inner side of the kovar frame.

4. The millimeter wave radio frequency chip BGA package tube shell according to claim 1, characterized in that: The thickness of the first metal plating layer is 0.2 mm, and the height of the isolated copper pillar is 0.8 mm.

5. The millimeter wave radio frequency chip BGA package tube shell according to claim 1, characterized in that: The BGA balls form twelve radio frequency interfaces and twelve low frequency interfaces.

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