Radio frequency connection structure for glass-based multilayer SiP package

Abstract

The application relates to the technical field of radio frequency front ends, and particularly discloses a radio frequency connecting structure based on a multilayer SiP package of a glass substrate, which comprises, from top to bottom, a ground metal layer one, a dielectric layer one, a signal metal layer, a dielectric layer two and a ground metal layer two which are stacked; the signal metal layer comprises a microstrip line, a strip line and a cut-angle microstrip; the strip line and the cut-angle microstrip are arranged on the same side and are connected with the microstrip line respectively; and a metal through hole is arranged on the dielectric layer two and located on the outer side of the cut-angle microstrip. The application meets the required line width of a bonding pad, reduces the transmission loss of the microstrip line to the strip line, and improves the transmission performance of signals in a link.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radio frequency front end, more particularly, to a radio frequency connection structure based on a glass-based multi-layer SiP package. BACKGROUND

[0002] With the rapid development of communication technology, the design of radio frequency circuit not only requires smaller size, but also requires higher signal speed, power capacity and integration.

[0003] SiP (System in Package) technology integrates different functional bare chips into a substrate in a 2D or 3D manner to realize a system-on-chip. Three-dimensional interconnection manufactured by glass via has unique advantages in the field of radio frequency chip integration due to its low loss, low cost and high density, and has become a hot spot for 3D packaging of high-frequency chips.

[0004] In SiP packaging, microstrip lines and striplines are two common transmission lines, and interconnection conversion of these two structures is often required in the packaging structure. In particular, when using a lead to bond the chip and the substrate at the edge of the microcavity, in order to meet the size of the bonding pad, the coplanar waveguide type transmission line with narrow line width cannot be used, and the bonding pad is usually implemented by a microstrip line with a larger size, so that the radio frequency signal is transmitted from the microstrip line part of the pad to the stripline part inside the substrate, thereby realizing maximum power transmission of the system. In this structure, the microstrip line and the stripline are designed with different line widths to meet the characteristic impedance consistent with the chip pin, and the connection between the striplines with different line widths will cause impedance discontinuity, increase the insertion loss, reduce the return loss, and affect the transmission of the radio frequency signal.

[0005] The traditional microstrip line and stripline conversion part usually adopts direct connection or 45° angle cut corner connection, and these two connection methods introduce large insertion loss, especially at high frequency, the multi-chip link will increase the loss due to the conversion of multiple microstrip lines and striplines, consume power, and reduce the link efficiency. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a radio frequency connection structure based on a glass-based multi-layer SiP package, which meets the required line width of the bonding pad and reduces the transmission loss of the microstrip line to the stripline, and improves the transmission performance of the signal in the link.

[0007] The solution adopted by the present application to solve the technical problem is:

[0008] A radio frequency connection structure based on a glass-based multi-layer SiP package, comprising a ground metal layer one, a dielectric layer one, a signal metal layer, a dielectric layer two and a ground metal layer two which are stacked from top to bottom.

[0009] The signal metal layer comprises a microstrip line, a stripline and a cut-corner microstrip, the stripline and the cut-corner microstrip are disposed on the same side and connected to the microstrip respectively;

[0010] A metal via is disposed on the second dielectric layer and outside the cut-corner microstrip.

[0011] In some possible embodiments, the cut-corner microstrips are two groups and symmetrically disposed along the axis of the stripline; and there are at least two metal vias outside each group of cut-corner microstrips.

[0012] In some possible embodiments, a mounting cavity is formed between the two groups of cut-corner microstrips, and the stripline is mounted in the mounting cavity and protrudes out of the mounting cavity at one end away from the microstrip line.

[0013] Part of the microstrip line, the cut-corner microstrip and the stripline are exposed, and part of the stripline in the mounting cavity is located between the first dielectric layer and the second dielectric layer.

[0014] In some possible embodiments, the distance between the metal via close to the microstrip line and the cut-corner microstrip of each group of cut-corner microstrips and the distance between the metal via away from the microstrip line and the cut-corner microstrip of each group of cut-corner microstrips are ds1 and ds2 respectively, where ds1>ds2.

[0015] In some possible embodiments, ds1>ds2>w lim , w lim is the gap between the two metal vias adjacent to each group of cut-corner microstrips on the same side.

[0016] In some possible embodiments, the length of the cut-corner microstrip along the axis of the stripline is S.

[0017]

[0018] where N is the number of metal vias on the same side of each group of cut-corner microstrips, and N≥2.

[0019] R via is the radius of the metal via;

[0020] w1 is the width of the microstrip line;

[0021] w2 is the width of the stripline.

[0022] In some possible embodiments, the width w1 of the microstrip line and the width w2 of the stripline both satisfy the 50-ohm line width.

[0023] In some possible embodiments, the first dielectric layer is a glass dielectric layer made of multi-layer dielectric materials, and the thickness of the first dielectric layer is A, where 100 μm≤A≤1000 μm.

[0024] In some possible embodiments, the second dielectric layer is a glass dielectric layer, and is made of a multilayer dielectric material, and the thickness of the second dielectric layer is B, 100 μm≤B≤600 μm.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] The present application improves the size of the cut corner microstrip by setting the metal grounding via, realizes that the bonding pad can adopt the microstrip type of large pad, reduces the transmission loss of the microstrip line to the strip line, and improves the transmission performance of the signal in the link. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a top view of the present application;

[0028] Figure 2 is a side view of the present application;

[0029] Figure 3 is a signal transmission characteristic diagram of the cut corner microstrip size change with the microstrip line and the strip line conversion structure in embodiment 1 of the present application;

[0030] Figure 4 is a signal transmission characteristic diagram of the distance change between the two sides of the cut corner microstrip and the cut corner microstrip in embodiment 1 of the present application;

[0031] Figure 5 is a comparison diagram of the insertion loss and the return loss of the conversion structure of the prior art and the present application;

[0032] 1, the first grounding metal layer; 2, the first dielectric layer; 3, the signal metal layer; 31, the microstrip line; 32, the strip line; 33, the cut corner microstrip; 4, the second dielectric layer; 41, the metal via; 5, the second grounding metal layer. DETAILED DESCRIPTION

[0033] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship of two elements. The "first", "second" and similar words mentioned in the present application do not represent any order, quantity or importance, but only distinguish different components. Similarly, "one" or "a" and the like do not represent a quantity limit, but represent the existence of at least one. In the implementation of the present application, the association relationship of the associated objects is described as "and / or", which means that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist together, and B exists alone. In the description of the embodiments of the present application, unless otherwise specified, the meaning of "multiple" is two or more. For example, multiple positioning columns refer to two or more positioning columns. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0034] The present application will be described in detail below.

[0035] A glass-based multilayer SiP package radio frequency connection structure, comprising a ground metal layer one 1, a dielectric layer one 2, a signal metal layer 3, a dielectric layer two 4, a ground metal layer two 5 arranged in a stack from top to bottom;

[0036] The signal metal layer 3 comprises a microstrip line 31, a strip line 32 and a cut corner microstrip 33, the strip line 32 and the cut corner microstrip 33 are arranged on the same side and are respectively connected with the microstrip;

[0037] A metal via hole 41 is arranged on the dielectric layer two 4 and outside the cut corner microstrip 33;

[0038] The cut corner microstrip 33 is two groups and is symmetrically arranged along the axis of the strip line 32; the metal via hole 41 outside each group of cut corner microstrip 33 is at least two;

[0039] After the two groups of cut corner microstrips 33 are connected with the microstrip line 31, a mounting cavity is formed, the strip line 32 is mounted in the mounting cavity and the end away from the microstrip line 31 protrudes out of the mounting cavity;

[0040] The part of the microstrip line 31, the cut corner microstrip 33 and the strip line 32 in the mounting cavity is arranged in a bare state, that is, not covered by the dielectric layer one 2 and the metal layer one on the dielectric layer one 2, and the part of the strip line 32 in the mounting cavity is located between the dielectric layer one 2 and the dielectric layer two 4.

[0041] In some possible implementations, in each set of two adjacent sets of metal vias 41 on the same side of the chamfered microstrip 33, the distance between the metal via 41 closer to the microstrip line 31 and the chamfered microstrip 33 is ds1, and the distance between the metal via 41 farther from the microstrip line 31 and the chamfered microstrip 33 is ds2, where ds1 > ds2 > w lim w lim The gap between two adjacent sets of metal through holes 41 on the same side of each set of chamfered microstrips 33.

[0042] In some possible implementations, the length of the chamfered microstrip 33 along the axial direction of the strip line 32 is S;

[0043]

[0044] Where N is the number of metal vias 41 on the same side of a set of chamfered microstrips 33, and N≥2;

[0045] R via The radius of the metal through hole 41;

[0046] w1 is the width of the microstrip line 31;

[0047] w2 is the width of stripline 32; the width w1 of microstrip line 31 and the width w2 of stripline line 32 both satisfy a 50-ohm linewidth.

[0048] Example 1:

[0049] Based on the above structure, in this embodiment, the chamfered microstrip 33 consists of two groups. The second dielectric layer 4 is disposed above the second ground metal layer 5, the signal metal layer 3 is disposed on the second dielectric layer 4, the first dielectric layer 2 is disposed on the signal metal layer 3 and only a portion of the signal metal layer 3 is covered by the first dielectric layer 2, and the first ground metal layer 1 is disposed on the first dielectric layer 2. The fact that only a portion of the signal metal layer 3 is covered by the first dielectric layer 2 means that a portion of the structure of the stripline 32 will be covered by the first dielectric layer 2.

[0050] Two sets of metal through holes 41 are provided on the outer side of the second dielectric layer 4; both the first dielectric layer 2 and the second dielectric layer 4 are glass dielectric layers and are made of multilayer dielectric materials respectively; wherein, the thickness of the first dielectric layer 2 is A, 100μm≤A≤1000μm; the thickness of the second dielectric layer 4 is B, 100μm≤B≤600μm.

[0051] like Figure 3 The effect of the length of the chamfered microstrip 33 along the axis of the stripline 32 on the signal line transmission performance; Appendix Figure 3 In the middle, a = (w1 - w2) / 2, from Figure 3 As can be seen, the length s of the chamfered microstrip 33 changes, and the effects on loss and echo vary at different frequencies:

[0052] The longer the length is, the lower the transmission loss is, and the greater the return loss is at the frequency below 5 GHz.

[0053] The length-width ratio of the cut-corner microstrip 33 is 0.5 at the frequency above 5 GHz, which is more conducive to signal transmission.

[0054] The hole diameter and the hole spacing of the metal via hole 41 are set by the selected process, and the distances from the edges of the cut-corner microstrip 33 are ds1 and ds2, respectively, and ds1>ds2≥w is required. lim For example, when the hole spacing is 100 μm, ds1>ds2>100 μm.

[0055] Figure 4 The influence of the distance between the metal via hole 41 and the edge of the cut-corner microstrip 33 on the transmission performance is shown. Figure 4 As can be seen from the table, when ds1<ds2, the return loss and the insertion loss performance of the structure are better.

[0056] Figure 5 In (a), the transmission characteristics of the direct conversion (conventional structure), the structure with the cut-corner non-ground via hole, and the structure of the present application are compared. After adding the cut-corner structure, the return loss performance is improved at a lower frequency, but the optimization at a higher frequency is not obvious.

[0057] Figure 5 (b) is a comparison of the S21 parameters of the three structures. After adding the cut-corner structure, the performance of the insertion loss is optimized by about 0.05 dB in the frequency range. The structure with the cut-corner and the via hole of the present application improves the insertion loss in the entire frequency range, optimizes by about 0.05 dB in the low frequency range, and greatly optimizes at a high frequency. At the frequency of 20 GHz, the insertion loss is optimized from 1 dB to 0.15 dB. The insertion loss of the structure is controlled at 0.15 dB in the frequency band of 500 MHz-20 GHz, and the performance is excellent.

[0058] Therefore, by setting the metal ground via hole and improving the size of the cut-corner microstrip 33, the microstrip type with a large pad can be used for the bonding pad, the transmission loss of the microstrip line 31 to the strip line 32 is reduced, and the transmission performance of the signal in the link is improved.

[0059] The present application is not limited to the foregoing specific embodiments. The present application extends to any new feature or any new combination disclosed in the specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A radio frequency interconnect structure based on a glass-based multilayer SiP package, characterized in that, It includes, from top to bottom, a grounding metal layer 1, a dielectric layer 1, a signal metal layer, a dielectric layer 2, and a grounding metal layer 2; The signal metal layer includes microstrip lines, striplines, and chamfered microstrips, wherein the striplines and chamfered microstrips are disposed on the same side and are respectively connected to the microstrip lines; Metal vias are provided on the second dielectric layer and on the outside of the chamfered microstrips; the chamfered microstrips are in two groups and are symmetrically arranged along the axis of the strip line; each group of chamfered microstrips has at least two metal vias on the outside; The length of the chamfered microstrip along the axis of the strip line is S; ； Where N is the number of metal vias on the same side of a set of chamfered microstrips. ; The radius of the metal through hole; The width of the microstrip line; This represents the width of the strip.

2. The radio frequency connection structure based on a glass-based multilayer SiP package according to claim 1, characterized in that, A mounting cavity is formed between the two sets of chamfered microstrips, and the strip wire is installed in the mounting cavity with one end of the strip wire extending out of the mounting cavity away from the microstrip wire. The microstrip line, chamfered microstrip line, and strip line are partially exposed within the mounting cavity, with the telescopic mounting cavity portion of the strip line located between dielectric layer one and dielectric layer two.

3. The radio frequency connection structure based on a glass-based multilayer SiP package according to claim 1, characterized in that, In each set of chamfered microstrips, the distance between the metal via closest to the microstrip line and the chamfered microstrip in two adjacent sets of vias on the same side is... The distance between the metal via far from the microstrip line and the chamfered microstrip is ,in, .

4. The radio frequency connection structure based on a glass-based multilayer SiP package according to claim 3, characterized in that, , This refers to the gap between two adjacent sets of metal vias on the same side of each chamfered microstrip.

5. The radio frequency connection structure based on a glass-based multilayer SiP package according to claim 3, characterized in that, The microstrip line width and strip width All meet the 50-ohm linewidth requirement.

6. The radio frequency connection structure based on a glass-based multilayer SiP package according to claim 1, characterized in that, The first dielectric layer is a glass dielectric layer, made of multiple dielectric materials, and the thickness of the first dielectric layer is A. .

7. The radio frequency connection structure based on a glass-based multilayer SiP package according to claim 1, characterized in that, The second dielectric layer is a glass dielectric layer, made of multilayer dielectric materials, and the thickness of the second dielectric layer is B. .

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