Millimeter wave antenna-filter module

Abstract

An antenna-filter array module and a method for manufacturing the same are provided. One manufacturing method includes bonding a low-temperature co-fired ceramic (LTCC) sheet having multiple antennas and corresponding filters to a first side of a module PCB via a first set of solder balls. The module PCB has a coefficient of thermal expansion (CTE) within a predetermined range of the CTE of the radio PCB. The method also includes cutting the LTCC sheet into a plurality of reliability units after bonding, each reliability unit having a size smaller than a predetermined maximum reliability size.

Description

Technical Field

[0001] The present disclosure relates to wireless communications, and in particular to antenna-filter array modules and methods of manufacturing the same. Background Art

[0002] Integrated low temperature co-fired (LTCC) antenna-filter array modules have been proposed for use in millimeter wave (mmWave) fifth generation (5G) advanced antenna systems (AAS). Figure 1 As shown in , the wiring circuit for the antenna-filter array can also be integrated with the antenna-filter array. Figure 1 A top view and a cross-sectional side view of an antenna-filter array module 10 are shown. Antenna-filter array module 10 has an antenna-filter array 12, which includes an antenna layer 12a and a filter layer 12b above a wiring layer 12c. The antenna layer has a plurality of antenna elements arranged in an array of N rows with M elements in each row, where N and M are integers and may be equal.

[0003] exist Figure 1 In the example of FIG. 1 , there are four rows (N=M=4) of cross-polarized antenna elements 14 mounted on a radio printed circuit board (PCB) 16 via solder balls 18 .

[0004] While integrated LTCC antenna-filter array modules offer advantages over other antenna-filter integration solutions, such as higher radio frequency (RF) performance, smaller size, and lower cost, this design has proven unreliable for mmWave 5G AAS.

[0005] In a study evaluating the reliability of LTCC antenna-filter array modules mounted on a standard radio PCB, the Megatron-6, three sizes of LTCC antenna-filter modules were tested (25×25 mm, 12×12 mm, and 6×6 mm). Only the smallest 6×6 mm module sample, corresponding to a 1×1 (i.e., single element) 28 GHz antenna-filter unit, showed reliability results close to radio requirements. The two larger module samples failed during testing.

[0006] Technically, module reliability is determined by two main factors: one is the difference in coefficient of thermal expansion (CTE) mismatch between the antenna-filter array 12 and the radio PCB 16 on which it is mounted; the other is the size of the antenna-filter array 12 which determines the span of the solder balls 18 on the radio PCB 16.

[0007] Testing revealed that the failure could be attributed to solder ball cracking. This cracking is directly caused by alternating thermal stresses on the solder balls due to the mismatched CTEs. The greater the difference between the two CTEs, the greater the thermal stress on the solder balls. Furthermore, the greater the spacing between the solder balls, the greater the thermal stress on the solder balls. Generally speaking, larger module sizes require larger spacing between solder balls. Therefore, to improve module reliability, the CTE difference should be reduced, or ideally, the size of the LTCC antenna-filter array should be reduced.

[0008] However, because the antenna-filter array size (also referred to herein as size) is constrained by other design considerations such as avoiding grating lobes and reducing mutual coupling between antenna elements, reducing the size of the antenna-filter array is not an ideal option. Changing the difference between the CTEs is also impractical. Types of standard printed circuit board materials such as Megatron-6 and FR4 have similar CTEs of ~15ppm / C. In contrast, LTCC antenna-filter arrays typically have a CTE of ~7ppm / C, which is only half the CTE of Megatron-6 or FR4 PCBs. Since Megatron-6 and FR4 are widely used in the radio manufacturing industry, it is not feasible to use other materials for radio PCBs that may more closely match the CTE of the LTCC antenna-filter array.

[0009] Figure 2-5 Existing proposals that have attempted to address these reliability issues are shown. For example, Figure 2 A proposal using the well-known underfill technique is shown, wherein an underfill material 20 is located between the antenna-filter array 12 and the radio PCB 16. This technique is widely used in the industry to mount large chips on PCBs. Engineers do not prefer this method because it is messy and, once the chip is mounted, the underfill material 20 cannot be easily removed from the radio PCB 16.

[0010] Figure 3 A second proposal is shown which uses solder coated polymer balls 22. This type of connection ball is much softer than a conventional solder ball because the solder coated polymer ball has a polymer core inside. The disadvantage of this solution is its very high cost.

[0011] Figure 4A third proposal is shown, which uses an interposer 24 inserted between the LTCC antenna-filter array and the radio PCB. Because interposer 24 has a CTE between that of the LTCC antenna-filter array 12 and the radio PCB 16, it can reduce the thermal stress exerted on solder balls 18 placed between the antenna-filter array 12 and interposer 24. However, a CTE mismatch still exists between the antenna-filter array 12 and the interposer 24, so this proposal does not completely resolve the reliability issues of the LTCC antenna-filter array module 10.

[0012] Figure 5 A fourth prior art proposal is shown in which the antenna-filter array 12 is modified by cutting it into a plurality of single polarization antenna-filter elements 26 and then individually mounting these elements 26 on the radio PCB 16 by a standard reflow soldering process. Figure 1 LTCC antenna-filter array 12. However, as Figure 5 As shown in , during the reflow process, these individual LTCC antenna-filter elements may lose their alignment due to solder melting. As a result, the entire antenna array may have poor element alignment, which will lead to very poor beamforming performance. Summary of the Invention

[0013] Some embodiments advantageously provide an antenna-filter array module and a method for manufacturing the same. According to one aspect, the method includes identifying the maximum size of an LTCC antenna-filter unit that can be mounted on a radio PCB without reliability issues. This can be accomplished experimentally. In at least some embodiments, the method includes soldering an LTCC sheet (which may typically be larger than the identified maximum size and have at least two antenna elements) onto a selected module PCB, the CTE of which is close to or equal to the CTE of the radio PCB, the closer the two CTEs are, the greater the reliability of the antenna-filter array module. When assembling the antenna-filter array module, the selected module PCB is located between the LTCC sheet and the radio PCB. After soldering the LTCC sheet to the module PCB, the sheet is divided into antenna-filter units having a size no greater than the identified maximum size. Antenna-filter units having a size no greater than the identified maximum size are referred to herein as units without reliability issues, or more simply as reliability units.

[0014] According to one aspect, a method for manufacturing an antenna-filter array module includes at least two antenna elements in an antenna array on a low-temperature co-fired ceramic (LTCC) sheet that can be coupled to a radio printed circuit board (PCB). The method includes soldering the LTCC sheet having the at least two antenna elements to a first side of the module PCB, the soldering including soldering at a first solder joint located between the LTCC sheet and the module PCB, the module PCB being at least as large as the LTCC sheet. After soldering, the method includes cutting the LTCC sheet into reliability-free RIF units, each RIF unit being no larger than a predetermined maximum reliable size. The method further includes forming a plurality of second solder joints on a second side of the module PCB, opposite the first side of the module PCB, the second solder joints being configured to couple to the radio PCB.

[0015] According to this aspect, in some embodiments, the method further includes coupling the module PCB to the radio PCB, the coupling including soldering at a plurality of second solder points. In some embodiments, the difference between the coefficient of thermal expansion (CTE) of the module PCB and the CTE of the radio PCB is less than a predetermined amount. In some embodiments, the module PCB and the radio PCB are made of the same material and have the same CTE. In some embodiments, the size of the module PCB is larger than the area of ​​the LTCC sheet. In some embodiments, the size of the RIF unit is the size of one antenna element. In some embodiments, the size of the RIF unit is the size of two rows of two antenna elements per row. In some embodiments, the size of the LTCC sheet is N rows of M antenna elements per row, where N and M are integers. In some embodiments, the size of the RIF unit is the size of an antenna element of the at least two antenna elements. In some embodiments, the module PCB has the size of at least two RIF units. In some embodiments, the soldering structure is a solder ball or a bump.

[0016] According to another aspect, an antenna-filter array module is provided. The antenna-filter array module includes a module printed circuit board (PCB) having a first side and a second side. The first side has a first solder structure and is configured to be soldered to a low-temperature co-fired ceramic (LTCC) sheet, and the second side has a second solder structure and is configured to be coupled to a radio PCB. The antenna-filter array module further includes an LTCC sheet having at least two antenna elements and corresponding filters. The LTCC sheet is soldered to the first side of the module PCB at the first solder structure and can be cut into reliability-free RIF units, each RIF unit having a size no greater than a predetermined maximum reliable size.

[0017] According to this aspect, in some embodiments, the difference between the coefficient of thermal expansion (CTE) of the module PCB and the CTE of the radio PCB is selected to be less than a predetermined amount. In some embodiments, the module PCB and the radio PCB are of the same material and have the same CTE. In some embodiments, the size of the module PCB is larger than the area of ​​the LTCC sheet. In some embodiments, the size of the RIF unit is the size of one antenna element. In some embodiments, the size of the RIF unit is the size of two rows of two antenna elements per row. In some embodiments, the size of the LTCC sheet is the size of N rows of M antenna elements per row. In some embodiments, the size of the RIF unit is the size of an antenna element of the at least two antenna elements. In some embodiments, the module PCB has the same size as the LTCC sheet before cutting.

[0018] According to yet another aspect, a method for manufacturing an antenna-filter array module configured to be coupled to a radio printed circuit board (PCB) is provided. The antenna-filter array module includes a module PCB having a first side and a second side, positioning a first set of solder balls on the first side, and positioning a second set of solder balls on the second side. The method includes bonding a low-temperature co-fired ceramic (LTCC) sheet having a plurality of antennas and corresponding filters to the first side of the module PCB via the first set of solder balls, wherein the coefficient of thermal expansion (CTE) of the module PCB is within a predetermined range of the CTE of the radio PCB. The method further includes cutting the LTCC sheet into a plurality of reliability units after bonding, each reliability unit having a size less than a predetermined maximum reliability size.

[0019] According to this aspect, in some embodiments, the size of the module PCB is the size of the LTCC sheet.In some embodiments, the module PCB and the radio PCB are the same material and have the same CTE. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] A more complete understanding of the present embodiments and its attendant advantages and features will be more readily appreciated by reference to the following detailed description considered in conjunction with the accompanying drawings, in which:

[0021] Figure 1 Showing a top view and a cross-sectional side view of an antenna-filter array module;

[0022] Figure 2 Shows the application of underfill technology;

[0023] Figure 3 Shows the application of using solder coated polymer balls;

[0024] Figure 4 An interposer is shown inserted between the LTCC antenna-filter array and the radio PCB;

[0025] Figure 5 shows an array of misaligned LTCC antenna-filter elements where the elements are first cut and then bonded to a radio PCB via a set of solder balls;

[0026] Figure 6 One embodiment of an LTCC antenna-filter fabricated according to the principles set forth herein is shown;

[0027] Figure 7A 、 7B 7C show three steps for forming an antenna-filter array module according to the principles set forth herein;

[0028] Figure 8 An embodiment of an antenna-filter array module is shown, wherein the RIF is a 2×2 array of antenna elements;

[0029] Figure 9 Shown mounted on a radio PCB Figure 8 Embodiments of

[0030] Figure 10 is a flow chart of an exemplary process for manufacturing an antenna-filter array module; and

[0031] Figure 11 is a flow chart of an alternative exemplary process for manufacturing an antenna-filter array module. DETAILED DESCRIPTION

[0032] Before describing the exemplary embodiments in detail, it should be noted that the embodiments reside primarily in combinations of device components and process steps related to antenna-filter array modules and methods for manufacturing the same. Accordingly, components have been represented in the drawings by conventional symbols where appropriate, with only those specific details relevant to understanding the embodiments being shown to avoid cluttering the disclosure with details that would be readily apparent to one of ordinary skill in the art having the benefit of the description herein.

[0033] As used herein, relational terms such as "first" and "second," "top" and "bottom," and the like may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements.

[0034] Referring again to the drawings, wherein like reference numerals refer to like elements, Figure 6An embodiment of an antenna-filter array module 30 is shown that solves the aforementioned problems of CTE mismatch and large spacing between solder balls 32 leading to unreliability without introducing problems such as dirty underfill, expensive solder-coated polymer balls, and antenna element misalignment. The components of the antenna-filter array module 30 include LTCC antenna-filter elements 34, a module PCB 36, and two layers of solder balls / bumps 32 or other solder structures at suitable solder points. Figure 6 As shown in FIG, the antenna-filter array module 30 has antenna-filter units (elements) 34, each of which has an antenna design on a top layer 38 and a filter design on a lower layer 39 of the antenna-filter unit 34. In some embodiments, if desired, wiring circuits for the antenna 38 and filter 39 arrays, such as transmission lines and splitters / combiners, can be designed within the module PCB 36. In addition, depending on the radio PCB 40 assembly process, the two layers of solder balls / bumps 32 can have different melting temperatures. Note that although Figure 6 It is disclosed that each antenna-filter unit 34 has only one antenna element, but it is noted that each antenna-filter unit can have more than one antenna element. Different arrays of antenna elements can form antenna-filter units. For example, see the detailed discussion below. Figure 8 2×2 antenna-filter unit. Note also that radio PCB 40 can be a known / existing radio PCB, such as radio PCB 16. In other words, the LTCC antenna-filter module disclosed herein is backward compatible and can be coupled to existing radio PCBs, and is forward compatible and can be coupled to radio PCBs yet to be developed.

[0035] Figures 7A-7C Shown are steps for one embodiment of a method for making the LTCC antenna-filter array module 30 disclosed herein. The method begins with an LTCC sheet 42 having an array of at least two antenna elements (eg, antenna-filter elements 34) with their underlying filters.

[0036] Step 1 Figure 7A ): The LTCC sheet 42 is mounted to the first side of the module PCB 36 via solder structures at solder joints, where the module PCB 36 is selected to have a CTE that is the same as or close to the CTE of the intended radio PCB.

[0037] Step 2 Figure 7B): Segment (cut) the LTCC sheet 42 into antenna-filter units 34, the size of which is the same as the largest LTCC antenna-filter array identified without reliability issues. Such antenna-filter units are referred to as reliability-free (RIF) units 46. Note that this step can be performed after step 1 to avoid Figure 5 Therefore, the dividing line 44 indicates the boundary of the RIF unit 46.

[0038] Step 3 Figure 7C ): Clean all separation debris and create solder joints on the second side of the module PCB 36 opposite the first side of the module PCB 36.

[0039] Please note, Figure 7B and 7C Steps 2 and 3 in the figure depict only one embodiment, where the reliability-free unit is a single antenna element (a 1×1 array), the minimum array size. In general, the reliability-free unit can be an N×M array, where N and M are integers that can be equal. The size of the RIF unit can depend on the LTCC material and PCB material used.

[0040] Figure 8 The top view and the cross-sectional side view of the LTCC antenna-filter array module 30 are shown, wherein the RIF unit 46 is a 2×2 array. Figure 8 In the example shown, the LTCC sheet has 16 dual-polarized antenna elements and is cut into four quadrants, each of which is occupied by a different RIF unit 46. Note that in some embodiments, each of the 16 dual-polarized antenna elements can be composed of two vertical antennas. Other antenna elements with different polarizations can also be used.

[0041] Thus, once bonded to the module PCB 36, the LTCC sheet 42 is singulated to create small, mechanically independent units, defined in Figure 7 by singulation lines 44, wherein each such unit is reliability issue free (RIF). For these units, there are no reliability issues caused by thermal expansion mismatches or excessive spacing between edge solder joints (such as solder balls or bumps) on the first side of the module PCB 36, because no unit is larger than the largest LTCC antenna-filter array size identified without reliability issues.

[0042] When, for example, Figure 6 and Figure 9When the LTCC antenna-filter module is mounted on the radio PCB using the second-side solder joints shown in FIG, and when the CTE of module PCB 36 is equal to or close to the CTE of radio PCB 40, there is little or no thermal mismatch between module PCB 36 and radio PCB 40. Therefore, the second set of solder structures on the second side of module PCB 36 should not present reliability issues.

[0043] For the reasons described above, the entire LTCC antenna-filter array module 30, as manufactured according to the above steps, should not have reliability issues when mounted on a radio PCB 40. Therefore, some embodiments provide a comprehensive solution to the reliability issues of the LTCC antenna-filter array module 30 mounted on a radio PCB 40. The LTCC antenna-filter array module 30 described herein can be simply mounted on a radio PCB 40 at low cost. Furthermore, in at least some embodiments, the LTCC antenna-filter array module 30 has higher beamforming performance than the aforementioned existing solution proposals because all antenna-filter elements are aligned and because the gaps between adjacent antenna-filter elements block surface-propagating electromagnetic waves that degrade beamforming performance. Furthermore, because the LTCC antenna-filter array module is a physical module, the assembly yield of the radio manufacturing is not affected by the presence of the module.

[0044] Figure 10 is a flow chart of an exemplary process for manufacturing an antenna-filter array module. The process includes soldering an LTCC sheet 42 having at least two antenna elements to a first side of a module PCB, including soldering at a first solder joint located between the LTCC sheet 42 and the module PCB 36, wherein the module PCB 36 is at least as large as the LTCC sheet 42 (block S100). The process also includes cutting the LTCC sheet 42 into reliability-free RIF units 46, each RIF unit 46 being no larger than a predetermined maximum reliable size (block S102). The process further includes forming a plurality of second solder joints (e.g., solder balls / bumps 32) on a second side of the module PCB 36, opposite the first side of the module PCB, wherein the second solder joints are configured to couple to the radio PCB 40 (block S104).

[0045] Figure 11is a flow chart of an alternative exemplary process for manufacturing an antenna-filter array module 30. The process (block S106) includes bonding a low temperature co-fired ceramic (LTCC) sheet 42 having a plurality of antennas and corresponding filters (to form antenna-filter elements 34) to a first side of a module PCB 36 via a first set of solder balls 32, the module PCB 36 having a coefficient of thermal expansion (CTE) within a predetermined amount of the CTE of the radio PCB 40. The process further includes cutting the LTCC sheet 42 into a plurality of reliability units 46 after bonding, each reliability unit 46 having a size less than a predetermined maximum reliable size.

[0046] Therefore, some embodiments described herein include LTCC antenna-filter modules designed with low cost, small size, and high performance in the mmWave 5G spectrum (with NR AAS), eliminating the last reliability issue of LTCC modules on radio PCBs.

[0047] According to one aspect, a method for manufacturing an antenna-filter array module 30 includes at least two antenna elements on a low-temperature co-fired ceramic (LTCC) sheet 42 in an antenna array that can be coupled to a radio printed circuit board (PCB) 40. The method includes soldering the LTCC sheet 42 having the at least two antenna elements to a first side of the module PCB 36, including soldering at a first solder joint located between the LTCC sheet 42 and the module PCB 36, wherein the module PCB 36 is at least as large as the LTCC sheet 42. After soldering, the method includes cutting the LTCC sheet 42 into reliability-free RIF units 46, each RIF unit 46 having a size no greater than a predetermined maximum reliable size. The method further includes forming a plurality of second solder joints on a second side of the module PCB 36, opposite the first side of the module PCB 36, wherein the second solder joints are configured to couple to the radio PCB 40.

[0048] According to this aspect, in some embodiments, the method further includes coupling module PCB 36 to the radio PCB, the coupling comprising soldering at a plurality of second solder points. In some embodiments, the difference between the coefficient of thermal expansion (CTE) of module PCB 36 and the CTE of the radio PCB is less than a predetermined amount. In some embodiments, module PCB 36 and radio PCB 40 are made of the same material and have the same CTE. In some embodiments, the size of module PCB 36 is larger than the area of ​​LTCC sheet 42. In some embodiments, the size of RIF unit 46 is the size of one antenna element. In some embodiments, the size of RIF unit 46 is the size of two rows of two antenna elements per row. In some embodiments, the size of LTCC sheet 42 is N rows of M antenna elements per row, where N and M are integers. In some embodiments, the size of RIF unit 46 is the size of an antenna element in at least two antenna elements. In some embodiments, module PCB 36 is the size of at least two RIF units. In some embodiments, the soldering structure is a solder ball or bump.

[0049] According to another aspect, an antenna-filter array module 30 is provided. The antenna-filter array module includes a module printed circuit board PCB 36 having a first side and a second side. The first side has a first solder structure and is configured to be soldered to a low-temperature co-fired ceramic (LTCC) sheet 42. The second side has a second solder structure and is configured to be coupled to a radio PCB. The antenna-filter array module further includes an LTCC sheet 42 having at least two antenna elements and corresponding filters. The LTCC sheet 42 is soldered to the first side of the module PCB 36 at the first solder structure and can be cut into reliability-free RIF cells 46, each RIF cell having a size no larger than a predetermined maximum reliable size.

[0050] In this regard, in some embodiments, the difference between the coefficient of thermal expansion (CTE) of module PCB 36 and the CTE of the radio PCB is selected to be less than a predetermined amount. In some embodiments, module PCB 36 and radio PCB 40 are made of the same material and have the same CTE. In some embodiments, the size of module PCB 36 is larger than the area of ​​LTCC sheet 42. In some embodiments, the size of the RIF unit is the size of one antenna element. In some embodiments, the size of the RIF unit is the size of two rows of two antenna elements per row. In some embodiments, the size of the LTCC sheet 42 is the size of N rows of M antenna elements per row. In some embodiments, the size of the RIF unit is the size of an antenna element in at least two antenna elements. In some embodiments, module PCB 36 is the same size as the LTCC sheet 42 before dicing.

[0051] According to yet another aspect, a method for manufacturing an antenna-filter array module configured to be coupled to a radio printed circuit board (PCB) is provided. The antenna-filter array module includes a module PCB 36 having a first side and a second side, a first set of solder balls positioned on the first side, and a second set of solder balls positioned on the second side. The method includes bonding a low-temperature co-fired ceramic (LTCC) sheet having a plurality of antennas and corresponding filters to the first side of the module PCB 36 via the first set of solder balls, wherein the coefficient of thermal expansion (CTE) of the module PCB 36 is within a predetermined amount of the CTE of the radio PCB 40. The method further includes, after bonding, cutting the LTCC sheet 42 into a plurality of reliability units, each reliability unit having a size less than or equal to a predetermined maximum reliability size.

[0052] In this regard, in some embodiments, the module PCB 36 is the size of the LTCC sheet 42. In some embodiments, the module PCB 36 and the radio PCB 40 are the same material and have the same CTE.

[0053] In conjunction with the above description and accompanying drawings, many different embodiments have been disclosed herein. It will be understood that it would be unduly repetitive and obfuscating to describe and illustrate verbatim every combination and subcombination of these embodiments. Therefore, all embodiments may be combined in any manner and / or combination, and this specification, including the accompanying drawings, should be construed as constituting a complete written description of all combinations and subcombinations of the embodiments described herein, as well as the manner and process of making and using them, and should support claims to any such combination or subcombination.

[0054] Explanation of abbreviations

[0055] AAS Advanced Antenna System

[0056] CTE coefficient of thermal expansion

[0057] EM electromagnetic LTCC low temperature co-fired ceramics

[0058] Those skilled in the art will appreciate that the embodiments described herein are not limited to what has been particularly shown and described hereinabove. Furthermore, unless otherwise indicated above, it should be noted that all drawings are not drawn to scale. In light of the above teachings, various modifications and variations are possible without departing from the scope of the following claims.

Claims

1. A method of manufacturing an antenna-filter array module (30), the module comprising at least two antenna elements in an antenna array on a low temperature co-fired ceramic (LTCC) sheet (42) that can be coupled to a radio printed circuit board (PCB), the method comprising: Soldering (S100) the LTCC sheet (42) having the at least two antenna elements to a first side of a module PCB (36), the soldering comprising soldering at a first soldering point between the LTCC sheet (42) and the module PCB (36), the module PCB (36) being at least as large as the LTCC sheet (42); Cutting (S102) the LTCC sheet (42) into RIF units (46) without reliability issues, wherein the size of each RIF unit (46) is not greater than a predetermined maximum reliable size; as well as A plurality of second soldering points are formed (S104) on a second side of the module PCB (36) opposite to the first side of the module PCB (36), the plurality of second soldering points being configured to couple with the radio PCB.

2. The method of claim 1, further comprising: The module PCB (36) is coupled to the radio PCB (40), the coupling comprising soldering at the plurality of second solder points.

3. The method according to any one of claims 1 and 2, wherein A difference between a coefficient of thermal expansion (CTE) of the module PCB (36) and a CTE of the radio PCB (40) is less than a predetermined amount.

4. The method according to any one of claims 1 and 2, wherein The module PCB (36) and the radio PCB (40) are of the same material and have the same CTE.

5. The method according to any one of claims 1 and 2, wherein The size of the module PCB (36) is larger than the area of ​​the LTCC sheet (42).

6. The method according to any one of claims 1 and 2, wherein The size of the RIF unit is the size of one antenna element.

7. The method according to any one of claims 1 and 2, wherein The size of the RIF unit is that of two rows of two antenna elements per row.

8. The method according to any one of claims 1 and 2, wherein The size of the LTCC sheet (42) is N rows of M antenna elements per row, where N and M are integers.

9. The method of claim 1, wherein: The module PCB (36) has a size of at least two RIF units (46).

10. The method of claim 1, wherein: The solder structures are solder balls or bumps (32).

11. A method of manufacturing an antenna-filter array module (30), the module being configured to be coupled to a radio printed circuit board (PCB) (40), the antenna-filter array module (30) having a module PCB (36), the module PCB (36) having a first side and a second side, positioning a first set of solder balls (32) on the first side and positioning a second set of solder balls (32) on the second side, the method comprising: bonding (S106) a low temperature co-fired ceramic (LTCC) sheet (42) having a plurality of antennas and corresponding filters to a first side of the module PCB (36) via a first set of solder balls (32), the module PCB (36) having a coefficient of thermal expansion (CTE) within a predetermined amount of the CTE of the radio PCB; as well as After the bonding, the LTCC sheet (42) is cut (S108) into a plurality of reliability units (46), and the size of each reliability unit (46) is smaller than a predetermined maximum reliability size.

12. The method of claim 11, wherein: The size of the module PCB (36) is the size of the LTCC sheet (42).

13. The method according to any one of claims 11 and 12, wherein The module PCB (36) and the radio PCB (40) are of the same material and have the same CTE.

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