Radio frequency ceramic tube shell with compact electromagnetic isolation structure and packaging method

Abstract

The invention relates to the technical field of semiconductor packaging, and particularly discloses a radio frequency ceramic tube shell with a compact electromagnetic isolation structure and a packaging method, the radio frequency ceramic tube shell comprises an active ceramic shell provided with a metal box dam, and a metal cover plate installed on the metal box dam; a plurality of cavities matched with the chip are arranged in the metal box dam, and a bonding area is arranged between two adjacent groups of cavities; the bonding region is communicated with the two adjacent groups of cavities; a plurality of groups of lower shielding columns are arranged on the active ceramic shell and in the bonding area, and upper shielding columns matched with the upper shielding columns in an inserting manner are arranged on the metal cover plate; the inner side face of the metal box dam, the upper shielding column, the lower shielding column and the metal cover plate are matched with one another to form an electromagnetic isolation cavity used for installing a plurality of chips. The invention further discloses a packaging method, the metal characteristics of the metal box dam and the metal cover plate are fully utilized, shielding is fused, the electromagnetic isolation effect is excellent, the structure is compact, the assembly process is simple, the yield is high, and the reliability is high.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor packaging, and more specifically, to a radio frequency ceramic package and a packaging method with a compact electromagnetic isolation structure. Background Art

[0002] Semiconductor chips need to be packaged before use. Packaging mainly has four important functions: protecting the chip from damage caused by the environment and transmission; providing interconnections for the signal input and output of the chip; physically supporting the chip; and dissipating heat. Generally speaking, the semiconductor chip to the final electronic product needs to go through three-level packaging. The first-level packaging packages the separated semiconductor chips into independent functional modules; the second-level packaging installs these functional modules on the mother printed circuit board to achieve the overall function; the third-level packaging installs this mother printed circuit board into the final product. The present invention belongs to the first-level packaging.

[0003] The implementation of the first-level packaging requires the use of a packaging package. At present, according to the material, it is mainly divided into plastic packages and ceramic packages. Among them, the plastic package has a low cost, but it cannot be airtight, has poor heat dissipation and poor radio frequency performance; while the ceramic package generally consists of a ceramic bottom plate, a metal dam welded on the ceramic bottom plate and a metal cover plate. Due to the high thermal conductivity and high-frequency low-loss characteristics of the ceramic material, its heat dissipation and radio frequency performance are excellent. At the same time, relying on the airtight environment formed by the dense ceramic bottom plate and the metal dam / cover plate, it plays a good role in protecting the internal chip and adapting to various harsh environments. Therefore, ceramic packages are widely used in projects with higher reliability requirements, such as military projects. The present invention mainly aims at this airtight and highly reliable ceramic package.

[0004] On the other hand, with the development of electronic devices to date, their integration density is getting higher and higher. An electromagnetic crosstalk problem becomes more and more prominent inside a packaging package, especially radio frequency signal crosstalk (the space transmission loss of radio frequency signals is low).

[0005] For the above-mentioned hermetic ceramic packages, traditional electromagnetic isolation is achieved by using metal isolation cavities or installing independent shielding structures after chip bonding. Among them, the metal isolation cavity itself has a large size. At the same time, the chip bonding position needs to be at a certain distance from the metal isolation cavity with a large depth to avoid hindering bonding, resulting in low integration. For the method of installing an independent shielding structure (such as an independent shielding cover) after chip bonding, due to the independence of its structure, it cannot utilize other metal-structured components within the package for combined shielding. Instead, other structures need to avoid it, resulting in low integration. For example, it cannot be combined with the outermost metal dam of the package for shielding, and instead, the metal dam needs to avoid it for assembly. In addition, the method of installing an independent shielding structure after chip bonding also requires extremely high precision in the chip bonding position. Otherwise, it will cause chip interference with the shielding structure and thus cannot be assembled. It also requires extremely high control over chip bonding overflow. Once the chip bonding overflows into the assembly area of the independent shielding structure, it will also cause it to be unable to be assembled.

[0006] In summary, these two traditional electromagnetic isolation methods face problems such as low integration, extremely high assembly process requirements, and thus low yield. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a radio frequency ceramic package with a compact electromagnetic isolation structure and a packaging method. The present invention makes full use of the metal properties of the metal dam and the metal cover plate for combined shielding. At the same time, the shielding posts are divided into upper and lower parts to solve the problem of the shielding structure hindering bonding. Together, they improve the integration of the shielding structure. It can also provide position identification for chip bonding and prevent chip bonding overflow, greatly reducing the process difficulty and improving the yield.

[0008] The solution adopted by the present invention to solve the technical problem is as follows:

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

[0010] A plurality of chambers for cooperating with chips are provided inside the metal dam, and a bonding area is provided between two adjacent sets of chambers; the bonding area communicates with the two adjacent sets of chambers;

[0011] A plurality of lower shielding posts are provided on the active ceramic housing and located in the bonding area, and a plurality of upper shielding posts are provided on the metal cover plate, which are arranged in one-to-one correspondence with the lower shielding posts and are inserted and matched;

[0012] The inner side surface of the metal dam, the upper shielding posts, the lower shielding posts, and the metal cover plate cooperate with each other to form an electromagnetic isolation cavity for installing a plurality of chips.

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

[0014] In some possible embodiments, a blind hole is provided on one side of the lower shielding column close to the upper shielding column; a protrusion is provided on the upper shielding column and is in plug-in fit with the blind hole.

[0015] In some possible embodiments, the active ceramic housing includes a ceramic bottom plate, a grounding metal layer printed on the ceramic bottom plate, an external connector provided on one side of the ceramic bottom plate away from the grounding metal layer, and a connecting device for connecting adjacent two groups of chips and between the chip and the external connector; the metal dam is mounted on the grounding metal layer.

[0016] In some possible embodiments, the external connector includes multiple groups of pads printed on one side of the ceramic bottom plate away from the grounding metal layer, and BGA solder balls soldered on the pads.

[0017] In some possible embodiments, multiple groups of lower shielding columns located in the same bonding area are arranged in a linear array period, and a gap for mounting the connecting device is formed between two adjacent groups of the lower shielding columns; the gap communicates two adjacent electromagnetic isolation cavities.

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

[0019] In some possible embodiments, the connecting device includes a radio frequency signal metal disk, a low frequency signal metal disk, and a patch cord.

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

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

[0022] Step S2: Bond the chip to the grounding metal layer;

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

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

[0025] Step S5: Solder and implant the BGA solder balls onto the pads on the lower surface of the lower ceramic bottom plate.

[0026] In some possible embodiments, when welding the upper shielding column to the lower shielding column, the welding surface is located on the side of the protrusion close to the lower shielding column.

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

[0028] In the present invention, shielding columns are only arranged in the bonding area, and the other positions are all complete metal isolation cavities, which minimizes the reduction of electromagnetic isolation degree caused by the spaced-apart shielding columns. Therefore, it has the characteristic of excellent electromagnetic isolation effect;

[0029] The present invention makes full use of the metal characteristics of the metal dam and the metal cover plate, combines with the shielding columns for integrated shielding, that is, the metal dam and the metal cover plate are used both as an airtight structure and as a shielding structure, with a compact structure;

[0030] In the present invention, shielding columns are arranged in a linear array with an extremely small pitch in the bonding area to achieve electromagnetic isolation, and connectors sandwiched between the linearly arranged shielding columns are used to realize the interconnection between chips and between the chip and the ceramic base plate, avoiding the use of traditional complete metal isolation cavities, with a compact structure;

[0031] In the present invention, the shielding column is divided into upper and lower halves. The lower half for installing the chip is basically at the same height as the chip and the transfer wire. In this way, when bonding the bonding wire, the shielding column will not hinder the bonding blade, minimizing the length of the transfer microstrip as much as possible, with a compact structure;

[0032] In the present invention, the shielding column is divided into upper and lower halves. The upper and lower halves have the same shape and corresponding positions. The lower shielding column and the chip are both located on the active ceramic package, and during the assembly process, the lower shielding column is assembled with the chip first. Therefore, the lower half of the lower shielding column will give a mark for the chip assembly position, and there will be no problem of interference between the shielding column and the chip due to assembly position deviation; as long as the adhesive overflow during chip bonding does not overflow higher than the lower shielding column for the lower shielding column with a certain height, there is no need for strict control; at the same time, the upper shielding column and the lower shielding column are nested and welded. On the one hand, it provides guidance for mechanical assembly, and on the other hand, the welding surface is inside the shielding column, which can avoid the loss of the chip caused by solder splash during welding; the present invention has a simple assembly process, thus greatly improving the qualified rate of the finished product;

[0033] The present invention has a complete metal frame and a metal cover plate. After they are completely welded, combined with the dense ceramic base plate, it has airtight characteristics and high reliability. Description of the Drawings

[0034] Figure 1 It is a structural exploded view of the radio frequency ceramic package in the present invention;

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

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

[0037] Figure 43D view of the present invention;

[0038] Figure 5 Structural schematic diagram of the metal enclosure in the present invention;

[0039] Wherein: 1. Active ceramic housing; 101. Ceramic bottom plate; 102. Grounding metal layer; 103. RF signal metal disc; 104. Low-frequency signal metal disc; 105. Metal dam; 1051. Chamber; 1052. Bonding area; 106. Lower shielding post; 1061. Blind hole; 107. Chip; 108. Bonding wire; 109. Pad; 110. BGA solder ball; 111. Jumper wire; 2. Metal cover; 201. Upper shielding post; 2011. Protrusion. Detailed implementation mode

[0040] In the present invention, unless otherwise clearly defined and limited, terms such as "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be directly connected, or indirectly connected through an intermediate medium, and can be the internal communication of two components or the interaction relationship between two components. The "first", "second" and similar words mentioned in this application do not represent any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "a" do not represent a quantity limit, but represent the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In the description of the embodiments of this application, unless otherwise stated, the meaning of "multiple" refers to two or more. For example, multiple positioning posts refer to two or more positioning posts. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

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

[0042] As Figures 1 - 5 shown:

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

[0044] A plurality of chambers 1051 cooperating with the chip 107 are arranged in the metal dam 105, and a bonding area 1052 is arranged between two adjacent groups of the chambers 1051; the bonding area 1052 is communicated with two adjacent groups of the chambers 1051;

[0045] A plurality of lower shielding posts 106 are provided on the active ceramic housing 1 and within the bonding area 1052, and a plurality of upper shielding posts 201 are provided on the metal cover plate 2, which are arranged in one-to-one correspondence with the upper shielding posts 201 and are inserted and fitted with each other.

[0046] The inner side surface of the metal dam 105, the upper shielding posts 201, the lower shielding posts 106, and the metal cover plate 2 cooperate with each other to form an electromagnetic isolation cavity for mounting a plurality of chips 107.

[0047] The upper shielding posts 201 and the lower shielding posts 106 are arranged in one-to-one correspondence and are cylindrical, with the same outer diameter.

[0048] In the present invention, the bonding area 1052 described is the place where bonding is required. In the present invention, the lower shielding posts 106 are only provided in the bonding area 1052, and together with the metal dam 105, the metal cover plate 2 with the upper shielding posts 201, and the grounding metal layer 102 provided on the active ceramic housing 1, they form an electromagnetic isolation cavity to achieve electromagnetic shielding of the chip 107. The electromagnetic isolation degree is low. Therefore, it is only used less in the places where bonding is required, which can ensure that the isolation degree of the shielding structure is at a relatively high level to the greatest extent.

[0049] In some possible implementation manners, the height of the lower shielding post 106 is H, and the height of the chip 107 is h, where 0.1 mm < H < 0.1 mm + h. With this setting, it will effectively ensure that the lower shielding post 106 has a certain height to provide a position identifier for bonding the chip 107 and prevent glue overflow during bonding of the chip 107. At the same time, since it maintains a height close to that of the chip 107, it will not hinder the bonding process.

[0050] In some possible implementation manners, a blind hole 1061 is provided on one side of the lower shielding post 106 close to the upper shielding post 201; a protrusion 2011 that is inserted and fitted with the blind hole 1061 is provided on the upper shielding post 201; the upper shielding post 201 and the lower shielding post 106 are inserted and fitted, 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 the shielding requirements are not strict, the upper shielding post 201 and the lower shielding post 106 can be inserted; 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 is 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, it can also effectively prevent solder from overflowing during welding of the upper shielding post 201 and the lower shielding post 106, avoiding damage to the chip 107 due to solder overflow.

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

[0053] Specifically, the external connector is used to achieve the external interconnection of the present invention, and it can be a BGA, or other forms such as an LCC, pins, etc.

[0054] In some possible embodiments, for the external connection of the present invention; the external connector includes multiple groups of pads 109 printed on a side of the ceramic bottom plate 101 away from the ground metal layer 102, and BGA solder balls 110 soldered on the pads 109.

[0055] In some possible embodiments, multiple groups of lower shielding posts 106 located in the same bonding area 1052 are arranged in a linear array period, and a gap for installing the connecting device is formed between two adjacent groups of the lower shielding posts 106 in the same bonding area 1052; the gap communicates two adjacent electromagnetic isolation cavities;

[0056] Adopting this setting enables two adjacent groups of chips 107 to share a bonding area 1052 and be connected through the connecting device; greatly improving the integration degree.

[0057] In some possible embodiments, the width of the connecting device is d, and the width of the gap is D, D = d + 0.2 mm; adopting this setting can ensure the installation of the connecting device on the one hand, and ensure electromagnetic shielding on the other hand.

[0058] In some possible embodiments, the connecting device includes a radio frequency signal metal disc 103, a low frequency signal metal disc 104, and a jumper wire 111;

[0059] The jumper wire 111, the radio frequency signal metal disc 103, and the low frequency signal metal disc 104 are clamped in the linear period array formed by the lower shielding posts 106. Each chip 107 is interconnected with the internal traces of the lower ceramic bottom plate 101 through a bonding wire 108 and communicates with the BGA solder ball 110, and finally is electrically connected to the outside through the BGA solder ball 110; the radio frequency signal metal disc 103 and the low frequency signal metal disc 104 realize signal interconnection with the chip 107;

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

[0061] On the other hand:

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

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

[0064] Step S2: Bond the chip 107 to the grounded metal layer 102;

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

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

[0067] Specifically, after assembling the metal cover plate 2 onto the active ceramic housing 1, welding should be performed such 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 airtight and electromagnetic isolation characteristics of the present invention;

[0068] Meanwhile, each pair of the lower shielding column 106 and the upper shielding column 201 should be welded together to ensure the electromagnetic isolation characteristic, and the welding surface is located on the lower surface of the upper shielding column 201. The lower edge of the protrusion 2011 is simultaneously located inside the blind hole 1061 of the upper shielding column 201 to avoid solder splashing and overflowing during welding and damaging the chip 107;

[0069] Step S5: Solder and implant the BGA balls 110 onto the pads 109 on the lower surface of the lower ceramic base plate 101.

[0070] Furthermore, the metal dam 105 and the lower shielding column 106 can be realized by a method of machining and then welding or bonding to the ceramic base plate 101, or can be realized by successive electroplating of copper;

[0071] The shielding columns (the upper shielding column 201 and the lower shielding column 106) are both columns, and they can achieve the electromagnetic isolation effect by being arranged in a linear array period, or can enclose any other shape to achieve the electromagnetic isolation effect;

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

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

Claims

1. A radio frequency ceramic tube shell with a compact electromagnetic isolation structure, characterized in that: It comprises an active ceramic housing provided with a metal dam, and a metal cover plate installed on the metal dam; A plurality of chambers matching the chip are arranged in the metal dam, and a bonding area is arranged between two adjacent groups of chambers; the bonding area is communicated with the two adjacent groups of chambers; A plurality of groups of lower shielding posts are arranged on the active ceramic housing and in the bonding area, and a plurality of groups of upper shielding posts are arranged on the metal cover plate and are arranged one-to-one with the upper shielding posts and are plug-fitted; The inner side surface of the metal dam, the upper shielding column, the lower shielding column and the metal cover plate cooperate with each other to form an electromagnetic isolation cavity for mounting multiple chips.

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

3. The radio frequency ceramic tube shell with a compact electromagnetic isolation structure according to claim 1, characterized in that: A blind hole is arranged on one side of the lower shielding column close to the upper shielding column; and a protrusion which is plugged and matched with the blind hole is arranged on the upper shielding column.

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

5. The radio frequency ceramic tube shell with a compact electromagnetic isolation structure according to claim 4, characterized in that: The external connection parts include a plurality of soldering pads printed on a side of the ceramic base plate away from the ground metal layer, and BGA soldering balls soldered on the soldering pads.

6. The radio frequency ceramic tube shell with a compact electromagnetic isolation structure according to claim 4, characterized in that: A plurality of groups of lower shielding posts located in the same bonding area are arranged periodically in a linear array, and a gap for installing a connecting device is formed between two adjacent groups of the lower shielding posts; the gap connects two adjacent groups of electromagnetic isolation cavities.

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

8. The radio frequency ceramic tube shell 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 a switching line.

9. A packaging method for a radio frequency ceramic tube shell with a compact electromagnetic isolation structure according to any one of claims 1 to 8, characterized in that: The specific steps include: Step S1: welding and assembling the metal dam and the lower shielding column onto the grounding metal layer printed on the active ceramic housing; Step S2: bonding the chip to the ground metal layer; Step S3: bonding and interconnecting the chip, the active ceramic housing, and the connecting device; Step S4: welding the metal cover plate to the active ceramic housing, the upper shielding column to the lower shielding column; Step S5: soldering the BGA solder balls to the solder pads on the lower surface of the lower ceramic base plate.

10. The packaging method of a radio frequency ceramic tube shell with a compact electromagnetic isolation structure according to claim 9, characterized in that: When welding the upper shielding column and the lower shielding column, the welding surface is located on the side of the protrusion close to the lower shielding column.

Images