A radio frequency ceramic housing with a compact electromagnetic isolation structure and a packaging method thereof.

Abstract

This invention relates to the field of semiconductor packaging technology, specifically disclosing a radio frequency (RF) ceramic housing with a compact electromagnetic isolation structure and a packaging method. The RF ceramic housing includes an active ceramic shell with a metal dam and a metal cover plate mounted on the metal dam. Multiple chambers that mate with chips are arranged within the metal dam, and a bonding area is provided between adjacent groups of chambers. The bonding area communicates with the adjacent groups of chambers. Multiple lower shielding pillars are arranged on the active ceramic shell within the bonding area, and upper shielding pillars that are inserted and mated with the upper shielding pillars are arranged on the metal cover plate. The inner surface of the metal dam, the upper shielding pillars, the lower shielding pillars, and the metal cover plate cooperate to form an electromagnetic isolation cavity for mounting multiple chips. The packaging method also discloses a method that fully utilizes the metallic properties of the metal dam and the metal cover plate, integrating shielding for excellent electromagnetic isolation, a compact structure, simple assembly process, high yield, and high reliability.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging technology, and more specifically, to a radio frequency ceramic housing with a compact electromagnetic isolation structure and a packaging method thereof. Background Technology

[0002] Semiconductor chips require packaging before use. Packaging has four main functions: protecting the chip from damage caused by the environment and transmission; providing interconnection for the chip's signal input and output; providing physical support for the chip; and heat dissipation. Generally, semiconductor chips undergo three levels of packaging before becoming final electronic products. The first level of packaging encapsulates the separate semiconductor chip into independent functional modules; the second level of packaging mounts these functional modules onto a motherboard to achieve overall functionality; and the third level of packaging mounts this motherboard into the final product. This invention belongs to the first level of packaging.

[0003] The implementation of Level 1 packaging requires the use of a packaging shell. Currently, based on materials, these shells are mainly divided into plastic shells and ceramic shells. Plastic shells are low in cost, but they are not airtight, have poor heat dissipation, and poor radio frequency performance. Ceramic shells, on the other hand, generally consist of a ceramic substrate, a metal dam welded to the ceramic substrate, and a metal cover plate. Due to the high thermal conductivity and low-loss characteristics of ceramic materials, they have excellent heat dissipation and radio frequency performance. At the same time, the airtight environment formed by the dense ceramic substrate and the metal dam / cover plate provides excellent protection for the internal chip and can withstand various harsh environments. Therefore, ceramic shells are widely used in projects with high reliability requirements, such as military projects. This invention mainly targets this type of airtight, high-reliability ceramic shell.

[0004] On the other hand, as electronic devices have developed to this point, their integration density has become increasingly higher. A single package often contains multiple types and purposes of semiconductor chips, making electromagnetic crosstalk problems more and more prominent, especially radio frequency signal crosstalk (radio frequency signals have low spatial transmission loss).

[0005] For the aforementioned hermetic ceramic housings, traditional methods employ either a metal cavity or a separate shielding structure installed after chip bonding to achieve electromagnetic isolation. The metal cavity itself is relatively large, and the chip bonding position needs to maintain a certain distance from the deep metal cavity to avoid obstructing bonding, resulting in low integration. The method of installing a separate shielding structure (such as a separate shielding cover) after chip bonding, due to its structural independence, cannot utilize other structures with metallic properties within the package for joint shielding; instead, other structures must avoid it, leading to low integration. For example, it cannot be used for joint shielding with the outermost metal dam of the package; instead, the metal dam must avoid it for assembly. Furthermore, the method of installing a separate shielding structure after chip bonding requires extremely high chip bonding positional accuracy; otherwise, the chip will interfere with the shielding structure, making assembly impossible. It also requires extremely high control of chip adhesive overflow; if chip adhesive overflows into the assembly area of ​​the separate shielding structure, it will also prevent assembly.

[0006] In summary, these two traditional electromagnetic isolation methods suffer from low integration, extremely high assembly process requirements, and consequently low yield rates. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide a radio frequency ceramic tube shell with a compact electromagnetic isolation structure and a packaging method. This invention makes full use of the metallic properties of the metal dam and the metal cover to integrate shielding. At the same time, the shielding pillar is divided into upper and lower parts to solve the problem of the shielding structure hindering bonding. Together, the two improve the integration of the shielding structure. It can also provide position marking for chip bonding and prevent the problem of chip bonding glue overflow, greatly reducing the process difficulty and improving the yield.

[0008] The solution adopted by this invention to solve the technical problem is:

[0009] This includes an active ceramic housing with a metal dam, and a metal cover plate installed on the metal dam;

[0010] The metal dam contains multiple chambers that mate with the chip, and a bonding area is provided between two adjacent groups of chambers; the bonding area is connected to the two adjacent groups of chambers.

[0011] Multiple sets of lower shielding posts are provided on the active ceramic housing and within the bonding area, and multiple sets of upper shielding posts are provided on the metal cover plate, which are corresponding to the upper shielding posts and are inserted into each other.

[0012] The inner side of the metal dam, the upper shielding column, the lower shielding column, and the metal cover plate work together to form an electromagnetic isolation cavity for installing multiple chips.

[0013] In some possible implementations, the height of the lower shielding post is H, and the height of the chip is h, where 0.1mm < H < 0.1mm + h.

[0014] In some possible implementations, a blind hole is provided on the side of the lower shielding post near the upper shielding post; and a protrusion is provided on the upper shielding post to engage with the blind hole.

[0015] In some possible implementations, the active ceramic housing includes a ceramic base plate, a grounding metal layer printed on the ceramic base plate, an external connector disposed on the side of the ceramic base plate away from the grounding metal layer, and a connecting device for connecting two adjacent sets of chips, and the chips and the external connector; the metal dam is mounted on the grounding metal layer.

[0016] In some possible implementations, the external component includes multiple sets of pads printed on the side of the ceramic substrate away from the ground metal layer, and BGA solder balls soldered onto the pads.

[0017] In some possible implementations, multiple sets of lower shielding posts located in the same bonding region are arranged in a linear array periodically, and a gap for mounting connecting devices is formed between two adjacent sets of lower shielding posts; the gap connects two adjacent sets of electromagnetic isolation cavities.

[0018] In some possible implementations, the width of the connecting device is d, and the width of the gap is D, where D = d + 0.2 mm.

[0019] In some possible implementations, the connection device includes a radio frequency signal metal disk, a low frequency signal metal disk, and an adapter cable.

[0020] A packaging method for a radio frequency ceramic housing with a compact electromagnetic isolation structure, as described above, specifically includes the following steps:

[0021] Step S1: Weld and assemble the metal dam and lower shielding post onto the grounding metal layer printed on the active ceramic shell;

[0022] Step S2: Attach the chip to the ground metal layer;

[0023] Step S3: Perform bonding and interconnection of the chip, active ceramic housing, and connecting devices;

[0024] Step S4: Weld the metal cover plate to the active ceramic housing, and the upper shielding post to the lower shielding post;

[0025] Step S5: Solder the BGA solder balls onto the pads on the lower surface of the ceramic substrate.

[0026] In some possible implementations, when welding the upper shielding post to the lower shielding post, the welding surface is located on the side of the protrusion closer to the lower shielding post.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] The present invention sets shielding pillars only in the bonding area, while other positions are complete metal cavities, which minimizes the reduction of electromagnetic isolation caused by the spaced shielding pillars. Therefore, it has the characteristics of excellent electromagnetic isolation effect.

[0029] This invention fully utilizes the metallic properties of metal dams and metal covers, and combines them with shielding columns to achieve integrated shielding. In other words, the metal dams and metal covers are used as both airtight structures and shielding structures, resulting in a compact structure.

[0030] This invention employs a linear array of periodically arranged shielding pillars with extremely small spacing in the bonding area to achieve electromagnetic isolation. Connectors sandwiched between the periodically arranged shielding pillars are used to achieve interconnection between chips and between chips and ceramic substrates, avoiding the use of traditional complete metal cavities, resulting in a compact structure.

[0031] This invention divides the shielding post into upper and lower halves. The lower half, where the chip is installed, is basically at the same height as the chip and the adapter cable. This way, when bonding the wire, the shielding post will not obstruct the bonding cutter, thus maximizing the compression of the length of the adapter microstrip and resulting in a compact structure.

[0032] This invention divides the shielding post into upper and lower halves, which are identical in shape and correspond to each other in position. Both the lower shielding post and the chip are located on the active ceramic housing. During assembly, the lower shielding post is assembled with the chip first. Therefore, the lower half of the lower shielding post will have a chip assembly position mark, preventing interference between the shielding post and the chip due to assembly position deviation. The lower shielding post has a certain height, and chip adhesive overflow can be controlled as long as it does not overflow above the lower shielding post, without strict control. At the same time, the upper and lower shielding posts are nested and welded, which provides guidance for mechanical assembly and, since the welding surface is inside the shielding post, avoids solder splashing and chip damage during welding. This invention has a simple assembly process, thereby greatly improving the yield rate of finished products.

[0033] This invention features a complete metal frame and a metal cover plate, which are welded together and combined with a dense ceramic base plate, resulting in airtightness and high reliability. Attached Figure Description

[0034] Figure 1 This is an exploded view of the structure of the radio frequency ceramic tube shell in this invention;

[0035] Figure 2 This is a structural view of the metal cover plate in this invention;

[0036] Figure 3 This is a structural view of the active ceramic housing in this invention;

[0037] Figure 4This is a three-dimensional view of the present invention;

[0038] Figure 5 This is a schematic diagram of the metal frame structure in this invention;

[0039] Among them: 1. Active ceramic housing; 101. Ceramic base plate; 102. Grounding metal layer; 103. RF signal metal disk; 104. Low frequency signal metal disk; 105. Metal dam; 1051. Chamber; 1052. Bonding area; 106. Lower shielding post; 1061. Blind via; 107. Chip; 108. Bonding wire; 109. Pad; 110. BGA solder ball; 111. Adapter cable; 2. Metal cover plate; 201. Upper shielding post; 2011. Protrusion. Detailed Implementation

[0040] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. The terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "one," etc., do not indicate a quantity limitation, but rather indicate the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more. For example, multiple positioning posts refer to two or more positioning posts. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0041] The present invention will now be described in detail.

[0042] like Figures 1-5 As shown:

[0043] It includes an active ceramic housing 1 with a metal dam 105 and a metal cover plate 2 installed on the metal dam 105;

[0044] The metal dam 105 contains a plurality of chambers 1051 that cooperate with the chip 107, and a bonding area 1052 is provided between two adjacent groups of chambers 1051; the bonding area 1052 is connected to the two adjacent groups of chambers 1051.

[0045] Multiple sets of lower shielding posts 106 are provided on the active ceramic housing 1 and within the bonding area 1052; multiple sets of upper shielding posts 201 are provided on the metal cover plate 2, which are corresponding to and inserted into the upper shielding posts 201.

[0046] The inner side of the metal dam 105, the upper shielding post 201, the lower shielding post 106, and the metal cover plate 2 cooperate to form an electromagnetic isolation cavity for mounting multiple chips 107.

[0047] The upper shielding post 201 and the lower shielding post 106 are set one-to-one and are cylindrical with the same outer diameter.

[0048] The bonding area 1052 described in this invention is the area where bonding is required. In this invention, the lower shielding post 106 is only set in the bonding area 1052. Together with the metal dam 105, the metal cover plate 2 with the upper shielding post 201, and the grounding metal layer 102 set on the active ceramic shell 1, an electromagnetic isolation cavity is formed to achieve electromagnetic shielding of the chip 107. The electromagnetic isolation is low. Therefore, it is used less frequently only in the area where bonding is required, so as to maximize the isolation of the shielding structure.

[0049] In some possible implementations, the height of the lower shielding post 106 is H, and the height of the chip 107 is h, where 0.1mm < H < 0.1mm + h. This arrangement effectively ensures that the lower shielding post 106 has a certain height to provide a position marker for bonding the chip 107 and prevent glue overflow during bonding of the chip 107. At the same time, since it maintains a similar height to the chip 107, it will not hinder the bonding process.

[0050] In some possible implementations, a blind hole 1061 is provided on the side of the lower shielding post 106 near the upper shielding post 201; a protrusion 2011 is provided on the upper shielding post 201 to engage with the blind hole 1061; the upper shielding post 201 and the lower shielding post 106 are engaged by an insertion, which effectively guides the metal cover plate 2 and connects the upper shielding post 201 and the lower shielding post 106; in some cases where shielding requirements are not strict, the upper shielding post 201 and the lower shielding post 106 can be engaged by an insertion; the blind hole 1061 is a cylindrical hole, and the protrusion 2011 will be cylindrical;

[0051] Of course, when there are high requirements for electromagnetic shielding, the electromagnetic shielding performance can be improved by welding the upper shielding post 201 and the lower shielding post 106. At this time, due to the setting of the protrusion 2011 and the blind hole 1061, the solder overflow during the welding of the upper shielding post 201 and the lower shielding post 106 can also be effectively prevented, thus avoiding damage to the chip 107 due to solder overflow.

[0052] In some possible implementations, the active ceramic housing 1 includes a ceramic base plate 101, a grounding metal layer 102 printed on the ceramic base plate 101, an external connector disposed on the side of the ceramic base plate 101 away from the grounding metal layer 102, and a connecting device for connecting two adjacent sets of chips 107, and connecting the chips 107 and the external connector; the metal dam 105 is mounted on the grounding metal layer 102; the connecting device is located in the bonding area 1052.

[0053] Specifically, the external component is used to realize the external interconnection of the present invention. It can be a BGA or other forms such as LCC, pins, etc.

[0054] In some possible implementations, for the external connection of the present invention, the external component includes multiple sets of pads 109 printed on the side of the ceramic substrate 101 away from the ground metal layer 102, and BGA solder balls 110 soldered on the pads 109.

[0055] In some possible implementations, multiple sets of lower shielding posts 106 located in the same bonding region 1052 are arranged in a linear array periodically, and a gap for mounting connecting devices is formed between two adjacent sets of lower shielding posts 106 in the same bonding region 1052; the gap connects two adjacent sets of electromagnetic isolation cavities.

[0056] This configuration allows two adjacent groups of chips 107 to share a bonding area 1052 and be connected through a connector, greatly improving the integration.

[0057] In some possible implementations, the width of the connecting device is d, and the width of the gap is D, where D = d + 0.2 mm; this arrangement ensures both the installation of the connecting device and electromagnetic shielding.

[0058] In some possible implementations, the connection device includes a radio frequency signal metal disk 103, a low frequency signal metal disk 104, and an adapter cable 111;

[0059] The adapter cable 111, the RF signal metal disk 103, and the low-frequency signal metal disk 104 are sandwiched in the linear periodic array formed by the lower shielding post 106. Each chip 107 is interconnected with the internal wiring of the lower ceramic substrate 101 through the bonding wire 108 and connected to the BGA solder ball 110. Finally, the BGA solder ball 110 is used to achieve electrical connection with the outside world. The RF signal metal disk 103 and the low-frequency signal metal disk 104 realize the signal interconnection with the chip 107.

[0060] The chips 107 located in different electromagnetic isolation cavities are electrically connected via adapter wire 111 and bonding wire 108.

[0061] on the other hand:

[0062] A packaging method for a radio frequency ceramic housing with a compact electromagnetic isolation structure, as described above, specifically includes the following steps:

[0063] Step S1: Weld and assemble the metal dam 105 and the lower shielding post 106 onto the grounding metal layer 102 printed on the active ceramic housing 1.

[0064] Step S2: Attach chip 107 to ground metal layer 102;

[0065] Step S3: Perform bonding and interconnection of chip 107, active ceramic housing 1, and connecting devices;

[0066] Step S4: Weld the metal cover plate 2 to the active ceramic housing 1, and the upper shielding post 201 to the lower shielding post 106;

[0067] Specifically, after the metal cover plate 2 is assembled onto the active ceramic housing 1, welding is performed to ensure that the entire upper surface of the metal dam 105 and the lower surface of the metal cover plate 2 are completely welded to ensure the airtightness and electromagnetic isolation characteristics of the present invention.

[0068] At the same time, each pair of lower shielding posts 106 and upper shielding posts 201 should be welded together to ensure electromagnetic isolation characteristics, and the welding surface should be located on the lower surface of the upper shielding post 201. The lower edge of the protrusion 2011 is also located inside the blind hole 1061 of the upper shielding post 201 to avoid solder splashing and overflowing during welding and damaging the chip 107.

[0069] Step S5: Solder the BGA solder balls 110 onto the pads 109 on the lower surface of the lower ceramic substrate 101.

[0070] Furthermore, the metal dam 105 and the lower shielding column 106 can be formed by machining and then welding or bonding to the ceramic base plate 101, or they can be formed by electroplating copper in succession.

[0071] The shielding posts (upper shielding post 201 and lower shielding post 106) are both posts. They can be arranged in a linear array periodically to achieve electromagnetic isolation, or they can be enclosed in any other shape to achieve electromagnetic isolation.

[0072] The upper shielding post 201 can be integrally machined with the metal cover plate 2, or it can be machined separately and then assembled onto the metal cover plate 2.

[0073] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A radio frequency ceramic housing with a compact electromagnetic isolation structure, characterized in that, This includes an active ceramic housing with a metal dam, and a metal cover plate installed on the metal dam; The metal dam contains multiple chambers that mate with the chip, and a bonding area is provided between two adjacent groups of chambers; the bonding area is connected to the two adjacent groups of chambers. Multiple sets of lower shielding posts are provided on the active ceramic housing and within the bonding area, and multiple sets of upper shielding posts are provided on the metal cover plate, which are corresponding to the upper shielding posts and are inserted into each other. The inner side of the metal dam, the upper shielding column, the lower shielding column, and the metal cover plate work together to form an electromagnetic isolation cavity for installing multiple chips.

2. The radio frequency ceramic housing with a compact electromagnetic isolation structure according to claim 1, characterized in that, The height of the lower shielding post is H, and the height of the chip is h, where 0.1mm < H < 0.1mm + h.

3. The radio frequency ceramic housing with a compact electromagnetic isolation structure according to claim 1, characterized in that, A blind hole is provided on the side of the lower shielding post near the upper shielding post; a protrusion is provided on the upper shielding post to engage with the blind hole.

4. The radio frequency ceramic housing with a compact electromagnetic isolation structure according to claim 1, characterized in that, The active ceramic housing includes a ceramic base plate, a grounding metal layer printed on the ceramic base plate, an external connector disposed on the side of the ceramic base plate away from the grounding metal layer, and a connecting device for connecting two adjacent sets of chips, and connecting the chips and the external connector; the metal dam is installed on the grounding metal layer.

5. A radio frequency ceramic housing with a compact electromagnetic isolation structure according to claim 4, characterized in that, The external component includes multiple sets of pads printed on the side of the ceramic substrate away from the ground metal layer, and BGA solder balls soldered onto the pads.

6. A radio frequency ceramic housing with a compact electromagnetic isolation structure according to claim 4, characterized in that, Multiple sets of lower shielding pillars located in the same bonding region are arranged in a linear array periodically, and a gap for installing connecting devices is formed between two adjacent sets of lower shielding pillars; the gap connects two adjacent sets of electromagnetic isolation cavities.

7. A radio frequency ceramic housing with a compact electromagnetic isolation structure according to claim 6, characterized in that, The width of the connecting device is d, and the width of the gap is D, where D = d + 0.2 mm.

8. A radio frequency ceramic housing with a compact electromagnetic isolation structure according to claim 4, characterized in that, The connecting device includes a radio frequency signal metal disk, a low frequency signal metal disk, and an adapter cable.

9. A packaging method for a radio frequency ceramic housing with a compact electromagnetic isolation structure according to any one of claims 1-8, characterized in that, Specifically, the following steps are included: Step S1: Weld and assemble the metal dam and lower shielding post onto the grounding metal layer printed on the active ceramic shell; Step S2: Attach the chip to the ground metal layer; Step S3: Perform bonding and interconnection of the chip, active ceramic housing, and connecting devices; Step S4: Weld the metal cover plate to the active ceramic housing, and the upper shielding post to the lower shielding post; Step S5: Solder the BGA solder balls onto the pads on the lower surface of the ceramic substrate.

10. The packaging method for a radio frequency ceramic housing with a compact electromagnetic isolation structure according to claim 9, characterized in that, When welding the upper and lower shielding posts, the welding surface should be located on the side of the protrusion closest to the lower shielding post.

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