Substrate integrated waveguide transmission structure and manufacturing method thereof

Abstract

A substrate integrated waveguide transmission structure comprises a first substrate, a second substrate, a bonding layer, a plurality of first via holes and a plurality of second via holes. The first substrate comprises a first conductor and a first dielectric layer which are stacked; the second substrate comprises a second conductor, a second dielectric layer and a third conductor which are stacked, and the second conductor is located on a part of the surface of the second dielectric layer; the bonding layer is located between the first substrate and the second substrate and is used for bonding the first dielectric layer, the second conductor and the second dielectric layer; each first via hole is connected with the first conductor and the third conductor; each second via hole penetrates through the first dielectric layer and is spaced from the second conductor; and the projection of the second conductor on the first conductor covers the projections of the plurality of second via holes on the first conductor. The invention further provides a manufacturing method of the substrate integrated waveguide transmission structure.

Description

Technical Field

[0001] The present application relates to the field of microwave guide technology, and in particular to a substrate integrated waveguide transmission structure and a manufacturing method thereof. Background Art

[0002] FPC transmission lines are often designed with strip lines or microstrip lines. When FPC transmission lines are used at millimeter wave frequencies, they have a high radiation loss problem. Therefore, more and more millimeter wave applications use SIW technology, which can achieve low-loss signal propagation at higher frequencies and has strong anti-electromagnetic interference capabilities. However, SIW has problems such as large size, difficult impedance matching, and the single-mode working width is limited to one octave, making it unsuitable for use in broadband microwave systems. Summary of the invention

[0003] A substrate integrated waveguide transmission structure includes a first substrate, a second substrate, a bonding layer, a plurality of first vias, and a plurality of second vias. The first substrate includes a first conductor and a first dielectric layer arranged in layers; the second substrate includes a second conductor, a second dielectric layer, and a third conductor arranged in layers, and the second conductor is located on a portion of the surface of the second dielectric layer; the bonding layer is located between the first substrate and the second substrate, bonding the first dielectric layer, the second conductor, and the second dielectric layer; each first via connects the first conductor and the third conductor; each second via penetrates the first dielectric layer and is spaced apart from the second conductor, and the projection of the second conductor on the first conductor covers the projections of the plurality of second vias on the first conductor.

[0004] In some embodiments of the present application, the aperture of the second via hole is less than or equal to one twentieth of the wavelength of the electromagnetic wave transmitted by the substrate integrated waveguide transmission structure.

[0005] In some embodiments of the present application, the plurality of second vias are arranged in two rows, and the distance between the second vias corresponding to the two rows is less than half of the distance between the first via and the second via.

[0006] In some embodiments of the present application, a surface of the second conductor facing away from the first via is exposed to the bonding layer.

[0007] In some embodiments of the present application, the glass transition temperature of the bonding layer is lower than the glass transition temperature of the first dielectric layer and the glass transition temperature of the second dielectric layer.

[0008] A method for manufacturing a substrate integrated waveguide transmission structure comprises the following steps: providing a first substrate, the first substrate comprising a first conductor and a first dielectric layer arranged in a stacked manner; forming a plurality of first conductive portions and a plurality of second conductive holes in the first substrate; providing a second substrate, the second substrate comprising a second conductor, a second dielectric layer and a third conductor arranged in a stacked manner, the second conductor being located on a partial surface of the second dielectric layer; forming a plurality of second conductive portions in the second substrate; providing an adhesive layer having a plurality of openings; bonding the first substrate and the second substrate with the adhesive layer; wherein each first conductive portion and / or each second conductive portion is accommodated in each opening and connected to each other to form a first conductive hole to connect the first conductor and the third conductor, and the projection of the second conductor on the first conductor covers the projection of the plurality of second conductive holes on the first conductor.

[0009] In some embodiments of the present application, the plurality of first conductive vias are arranged in one row, and the plurality of second conductive vias are arranged in two rows; the arrangement direction of the second conductive vias in each row is the same as the arrangement direction of the first conductive vias.

[0010] In some embodiments of the present application, a distance between two corresponding rows of second vias is less than half of a distance between a first via and a second via.

[0011] In some embodiments of the present application, the material used to form the first conductive hole and the second conductive hole is a mixture of resin and metal powder.

[0012] In some embodiments of the present application, the glass transition temperature of the bonding layer is lower than the glass transition temperature of the first dielectric layer and the glass transition temperature of the second dielectric layer, and the bonding layer is bonded to the first substrate and the second substrate by heat pressing.

[0013] The transmission structure provided in the embodiment of the present application, under the premise of meeting the requirements of low signal propagation loss at higher frequencies and strong anti-electromagnetic interference capability, the first conductive holes arranged at intervals and the first conductor and the third conductor form the side walls of the folded waveguide, which can effectively reduce the volume of the transmission structure; the second conductive holes arranged at intervals form ridge capacitances between the second conductors, and the transmission cutoff frequency can be adjusted through the ridge capacitances to adjust the use bandwidth of the transmission structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A schematic cross-sectional view of a substrate integrated waveguide transmission structure provided for some embodiments of the present application.

[0015] Figure 2 for Figure 1 The structural schematic diagram of the substrate integrated waveguide transmission structure is shown.

[0016] Figure 3 Schematic cross-sectional view of substrate integrated waveguide transmission structure provided for some other embodiments of the present application.

[0017] Figure 4 A schematic diagram of a process for forming a first conductive portion and a second conductive hole in a first substrate provided in an embodiment of the present application.

[0018] Figure 5 A schematic diagram of a process for forming a second conductive portion in a second substrate provided in an embodiment of the present application.

[0019] Figure 6 In accordance with Figure 4 The structure, bonding layer and Figure 5 A schematic cross-sectional view of a sequential arrangement of the structures shown.

[0020] Main component symbols

[0021] Transport Structure 100、100a First substrate 10 First conductor 11 The first dielectric layer 13 First blind hole 132 Adhesive layer 20 Opening 21 Second substrate 30 Second conductor 31 Second dielectric layer 33 Second blind hole 332 The third conductor 35 First via hole 40 The first conductive portion 41 The second conducting portion 43 The second via 50、50a distance D, d1, d2 DETAILED DESCRIPTION

[0022] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. In the following description, many specific details are set forth to facilitate a full understanding of the present application, and the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this article are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes all and any combination of one or more related listed items.

[0024] In the embodiments of the present application, for the convenience of description and not to limit the present application, the term "connection" used in the patent application specification and claims of the present application is not limited to physical or mechanical connection, whether direct or indirect. "Up", "down", "above", "below", "left", "right", etc. are only used to indicate relative position relationship. When the absolute position of the described object changes, the relative position relationship also changes accordingly.

[0025] See also Figure 1 as well as Figure 2The embodiment of the present application provides a substrate integrated waveguide (SIW) transmission structure 100, including a first substrate 10, an adhesive layer 20 and a second substrate 30 which are stacked. The transmission structure 100 also includes a plurality of first vias 40 and a plurality of second vias 50. Each first via 40 connects the first substrate 10 and the second substrate 30. Each second via 50 is connected to the first substrate 10 and is spaced apart from the second substrate 30.

[0026] The first substrate 10 includes a first conductor 11 and a first dielectric layer 13 which are stacked. The first conductor 11 is located on a surface of the first dielectric layer 13 away from the second substrate 30 . The first via 40 penetrates the first dielectric layer 13 and is connected to the first conductor 11 .

[0027] The second substrate 30 includes a second conductor 31, a second dielectric layer 33, and a third conductor 35 which are stacked. The second conductor 31 and the third conductor 35 are located on two opposite surfaces of the second dielectric layer 33. The second conductor 31 is located on the surface of the second dielectric layer 33 facing the first substrate 10, and the third conductor 35 is located on the surface of the second dielectric layer 33 facing away from the first substrate 10. The second conductor 31 is located on a portion of the surface of the second dielectric layer 33, and a portion of the surface of the second dielectric layer 33 is exposed to the second conductor 31.

[0028] The materials of the first dielectric layer 13 and the second dielectric layer 33 can be polyimide (PI), liquid crystal polymer (LCP), polytetrafluoroethylene (PTFE), polyethylene glycol terephthalate (PET), etc. The thickness of the first dielectric layer 13 and the thickness of the second dielectric layer 33 can both be 25 μm-200 μm.

[0029] The bonding layer 20 is located between the first substrate 10 and the second substrate 30. The bonding layer 20 bonds the first dielectric layer 13, the second conductor 31, and the surface of the second dielectric layer 33 exposed to the second conductor 31.

[0030] The material of the adhesive layer 20 may be polypropylene (PP), LCP, epoxy resin adhesive, olefin, soluble polytetrafluoroethylene (PFA), etc. The thickness of the adhesive layer 20 may be 15 μm-50 μm.

[0031] The plurality of first via holes 40 are spaced apart from each other and arranged in a straight line. Each first via hole 40 penetrates the first dielectric layer 13, the bonding layer 20 and the second dielectric layer 33. The two ends of each first via hole 40 are respectively connected to the first conductor 11 and the third conductor 35. The spaced apart first via holes 40, the first conductor 11 and the third conductor 35 form the side wall of the folded waveguide. The structural design of the folded waveguide can reduce the volume of the transmission structure 100, for example, by about 50%, compared with the structural design of the rectangular waveguide.

[0032] The distance between two first vias 40 is inversely proportional to the use frequency of the transmission structure 100. In some embodiments, the distance between two adjacent first vias 40 may be 0.3 mm-1 mm, so that the use frequency of the transmission structure 100 is within a suitable range.

[0033] The plurality of second vias 50 are spaced apart from each other and arranged in a line. Each second via 50 penetrates the first dielectric layer 13. Along the direction in which the transmission structure 100 is stacked, each second via 50 is spaced apart from the second conductor 31, and the projection of the second conductor 31 on the first conductor 11 covers the projections of the plurality of second vias 50 on the first conductor 11. A ridge capacitor is formed between the spaced second vias 50 and the second conductor 31, and the transmission cutoff frequency can be adjusted by the ridge capacitor.

[0034] The surface of the second conductor 31 facing away from the first via 40 is exposed to the bonding layer 20, and the remaining surface is connected to the bonding layer 20 and the second dielectric layer 33, that is, the waveguide transmission port of the transmission structure 100 is a microstrip line design, which can reduce signal reflection caused by impedance mismatch.

[0035] The aperture of the second conductive hole 50 is less than or equal to one twentieth of the wavelength of the electromagnetic wave transmitted by the transmission structure 100, that is, if the wavelength of the electromagnetic wave is λ and the aperture of the second conductive hole 50 is R, then R≤1 / 20λ, which can prevent the increase of radiation loss.

[0036] In some embodiments, the distance D between the second via 50 and the second conductor 31 can be reduced to increase the ridge capacitance and reduce the waveguide cutoff frequency, thereby increasing the bandwidth of the transmission structure 100. The distance D between the second via 50 and the second conductor 31 can be reduced by reducing the thickness of the bonding layer 20.

[0037] The second dielectric layer 33 and the third conductor 35 protrude from the first substrate 10 and can be used to adjust the distribution of the electric field in the waveguide to achieve the waveguide use frequency of the region.

[0038] See also Figure 3, in some other embodiments, the provided transmission structure 100a can increase the ridge capacitance and reduce the waveguide cut-off frequency by arranging two rows of second vias 50a, with each row of second vias 50a arranged in a straight line, the two rows of second vias 50a being spaced apart, and the arrangement direction of the second vias 50a in each row being the same as that of the first via 40. Arranging two rows of second vias 50a can also increase the ridge capacitance, reduce the waveguide cut-off frequency, and increase the usable bandwidth of the transmission structure 100a.

[0039] The distance between two corresponding second vias 50a is d1, and the distance between the first via 40 and the second via 50a is d2. The distance between two corresponding second vias 50a is less than half of the distance between the first via 40 and the second via 50a, that is, d1 < d2 / 2, which can avoid the occurrence of other modes and affect the operating frequency of the transmission structure 100a.

[0040] Please refer to Figures 4 to 6 and Figure 1 , the embodiments of the present application further provide a Figure 1 manufacturing method of the substrate integrated waveguide transmission structure 100 shown in the figure, which may include the following steps:

[0041] Step S1: Please refer to Figure 4 , provide a first substrate 10, where the first substrate 10 includes a first conductor 11 and a first dielectric layer 13 arranged in a stacked manner.

[0042] Two rows of first blind holes 132 are formed on the first substrate 10, the first blind holes 132 penetrate through the first dielectric layer 13, and a part of the surface of the first conductor 11 is exposed to the first dielectric layer 13.

[0043] Step S2: Please refer to Figure 4 , form a first conduction part 41 and a second via 50 in the first substrate 10.

[0044] Fill conductive paste in one row of the first blind holes 132 to form the first conduction part 41, and fill conductive paste in the other row of the first blind holes 132 to form the second via 50. Among them, the first conduction part 41 and the second via 50 can be formed after laser drilling, and the cross-sections of the first conduction part 41 and the second via 50 can be trapezoidal. In other embodiments, the shapes of the first conduction part 41 and the second via 50 are not limited.

[0045] Step S3: Please refer to Figure 5 , provide a second substrate 30, where the second substrate 30 includes a second conductor 31, a second dielectric layer 33, and a third conductor 35 arranged in a stacked manner, and the second conductor 31 is located on a part of the surface of the second dielectric layer 33.

[0046] A row of second blind holes 332 is provided on the second substrate 30, and each second blind hole 332 is provided in one-to-one correspondence with the first blind hole 132 for providing the first conductive portion 41. The second blind hole 332 penetrates the second dielectric layer 33, and a portion of the surface of the third conductor 35 is exposed to the second dielectric layer 33. The second blind hole 332 is spaced apart from the second conductor 31.

[0047] Step S4: Please refer to Figure 5 , a second conductive portion 43 is formed in the second substrate 30 .

[0048] Conductive paste is filled in each second blind hole 332 to form a second conductive portion 43, and each second conductive portion 43 is arranged one-to-one with the first conductive portion 41. The second conductive portion 43 can also be formed by laser drilling, and the cross section of the second conductive portion 43 can be trapezoidal.

[0049] Step S5: Please refer to Figure 6 , providing an adhesive layer 20 having a plurality of openings 21 .

[0050] Each opening 21 penetrates the adhesive layer 20 , and a position of each opening 21 is corresponding to each first conductive portion 41 and a corresponding second conductive portion 43 .

[0051] Step S6: Please refer to Figure 1 , the bonding layer 20 is bonded to the first substrate 10 and the second substrate 30 .

[0052] The first dielectric layer 13, the second dielectric layer 33 and the second conductor 31 are bonded to the bonding layer 20 in such a manner that they face inward. The glass transition temperature (Tg) of the bonding layer 20 is lower than the glass transition temperature of the first dielectric layer 13 and the glass transition temperature of the second dielectric layer 33, so that the bonding layer 20 can be bonded to the first substrate 10 and the second substrate 30 by heat pressing.

[0053] Among them, each first conductive portion 41 and / or each second conductive portion 43 is accommodated in each opening 21 and connected to each other to form a first conductive hole 40 to connect the first conductor 11 and the third conductor 35, and the projection of the second conductor 31 on the first conductor 11 covers the projections of multiple second conductive holes 50 on the first conductor 11; the second conductor 31 and the second conductive holes 50 are spaced apart by the adhesive layer 20.

[0054] The conductive paste used to form the first conductive hole 40 and the second conductive hole 50 is a mixture of resin and metal powder. The metal powder may contain components such as copper (Cu) and silver (Ag) with high electrical conductivity and tin (Sn) and bismuth (Bi) with low melting points. Through a hot pressing process, a metallurgical bond is formed between the first conductor 11 and the third conductor 35, thereby enhancing the bonding force between the first conductive hole 40, the second conductive hole 50 and the first conductor 11, the third conductor 35.

[0055] In the present embodiment, a stacked design process is adopted, in which a second via 50 that affects the ridge capacitance is formed by filling a conductive paste in the first blind hole 132. Compared with the electroplating process (which easily forms depressions and hole rings), the first blind hole 132 is fully filled with the conductive paste and has a smooth surface, which makes it easier to calculate the size of the controllable ridge capacitance. Moreover, by adjusting the thickness of the adhesive layer 20 disposed between the second via 50 and the second conductor 31, the distance between the second via 50 and the second conductor 31 can be adjusted, thereby adjusting the size of the ridge capacitance.

[0056] The transmission structure 100 (or 100a) provided in the embodiment of the present application, under the premise of meeting the requirements of low signal propagation loss at higher frequencies and strong anti-electromagnetic interference capability, the first via holes 40 arranged at intervals and the first conductor 11 and the third conductor 35 form the side walls of the folded waveguide, which can effectively reduce the volume of the transmission structure 100 (or 100a); the ridge capacitors are formed between the second via holes 50 arranged at intervals and the second conductor 31, and the transmission cutoff frequency can be adjusted through the ridge capacitors to adjust the use bandwidth of the transmission structure 100.

[0057] The above implementation modes are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the above preferred implementation modes, a person skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A substrate integrated waveguide transmission structure, characterized in that: include: A first substrate, comprising a first conductor and a first dielectric layer stacked in layers; The second substrate comprises a second conductor, a second dielectric layer and a third conductor which are stacked, wherein the second conductor is located on a part of the surface of the second dielectric layer; A bonding layer, located between the first substrate and the second substrate, bonding the first dielectric layer, the second conductor and the second dielectric layer; A plurality of first conductive vias, each of the first conductive vias connecting the first conductor and the third conductor; as well as A plurality of second vias, each of which penetrates the first dielectric layer and is spaced apart from the second conductor, and a projection of the second conductor on the first conductor covers projections of the plurality of second vias on the first conductor.

2. The substrate integrated waveguide transmission structure according to claim 1, characterized in that: The aperture of the second conductive hole is less than or equal to one twentieth of the wavelength of the electromagnetic wave transmitted by the substrate integrated waveguide transmission structure.

3. The substrate integrated waveguide transmission structure according to claim 1, characterized in that: The plurality of second conductive vias are arranged in two rows, and a distance between the second conductive vias corresponding to the two rows is less than half of a distance between the first conductive via and the second conductive via.

4. The substrate integrated waveguide transmission structure according to claim 1, characterized in that: A surface of the second conductor facing away from the first via is exposed to the bonding layer.

5. The substrate integrated waveguide transmission structure according to claim 1, characterized in that: The glass transition temperature of the bonding layer is lower than the glass transition temperature of the first dielectric layer and the glass transition temperature of the second dielectric layer.

6. A method for manufacturing a substrate integrated waveguide transmission structure, characterized in that: The following steps are involved: Providing a first substrate, wherein the first substrate comprises a first conductor and a first dielectric layer which are stacked; forming a plurality of first conductive portions and a plurality of second conductive holes in the first substrate; Providing a second substrate, the second substrate comprising a second conductor, a second dielectric layer and a third conductor which are stacked, the second conductor being located on a partial surface of the second dielectric layer; forming a plurality of second conductive portions in the second substrate; providing an adhesive layer having a plurality of openings; as well as Bonding the first substrate and the second substrate with the bonding layer; Each of the first conductive portions and / or each of the second conductive portions is accommodated in each of the openings and connected to each other to form a first conductive hole to connect the first conductor and the third conductor, and the projection of the second conductor on the first conductor covers the projections of multiple second conductive holes on the first conductor.

7. The method for manufacturing a substrate integrated waveguide transmission structure according to claim 6, characterized in that: The plurality of first conductive vias form one row, and the plurality of second conductive vias form two rows; the arrangement direction of the second conductive vias in each row is the same as the arrangement direction of the first conductive vias.

8. The method for manufacturing a substrate integrated waveguide transmission structure according to claim 7, characterized in that: The distance between two corresponding rows of the second conductive vias is less than half of the distance between the first conductive via and the second conductive via.

9. The method for manufacturing a substrate integrated waveguide transmission structure according to claim 6, characterized in that: The material used to form the first via hole and the second via hole is a mixture of resin and metal powder.

10. The method for manufacturing a substrate integrated waveguide transmission structure according to claim 6, characterized in that: The glass transition temperature of the bonding layer is lower than the glass transition temperature of the first dielectric layer and the glass transition temperature of the second dielectric layer, and the bonding layer is bonded to the first substrate and the second substrate by heat pressing.

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