JP3303226B2 - Flip chip mounting structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure in which two high-frequency transmission lines are mounted in a flip-chip manner using conductive bumps, and more particularly, to a structure in which two transmission lines having a coplanar structure or a ground planar structure are mutually mounted by a flip-chip mounting method. It relates to a structure for connection.

[0002]

2. Description of the Related Art FIG. 8 is a diagram showing an example of a structure of a connection portion between a conventional transmission line having a coplanar structure and a transmission line having a ground coplanar structure. (A) is a perspective view, (b) is a sectional view taken along line bb of (a), (c) is a sectional view taken along line cc of (b),
(D) is a sectional view taken along line dd of (b).

In order to electrically connect the transmission line 70 having the coplanar structure and the transmission line 80 having the ground coplanar structure, the two transmission lines 70 and 80 are brought close to each other to face each other, and the inductance component is reduced as much as possible. A conductive bump 74 connects between the signal line conductor 71 of the transmission line 70 and the signal line conductor 81 of the transmission line 80, and a ground conductor 72 of the transmission line 70 and a ground conductor 82 of the transmission line 80.
Are connected by a conductive bump 84. In addition,
The transmission line 70 extends in the upper left direction on the plane of FIG. 8A, and the transmission line 80 extends in the lower right direction.
Here, only the connection portion is shown. Other (b) ~
(D) also shows only the connection part.

[0004]

However, in the structure shown in FIG. 8, between the signal line conductor 71 and the ground conductor 72 in the regions 75 and 85 facing each other via the conductive bumps 74 and 84, or in the structure shown in FIG. A mismatch is caused in the characteristic impedance between the line conductor 81 and the ground conductor 82, and a high-frequency signal of several tens GHz or more is transmitted from the input section 76 of the transmission line 70 to the output section 86 of the transmission line 80 via the connection section. When transmitting, reflection at the connection increases, etc.
There is a disadvantage that the transmission characteristics are significantly deteriorated.

An object of the present invention is to provide a flip-chip mounting structure in which a good high-frequency transmission characteristic can be obtained without causing an impedance mismatch at a connection portion between two high-frequency transmission lines.

[0006]

For this purpose, the present invention provides a first transmission line having a coplanar structure or a ground coplanar structure in which a gap between a signal line conductor and a ground conductor formed on the same plane is g1, A second transmission line having a coplanar structure or a ground coplanar structure in which a gap between the line conductor and a ground conductor formed on the same surface is g2, and a signal line conductor and a ground conductor of the first and second transmission lines. A flip-chip mounting structure comprising: conductive bumps electrically opposed to each other and electrically connected to the signal line conductors of the first transmission line in regions of the first and second transmission lines facing each other. The gap with the ground conductor is g
3, the gap between the signal line conductor and the ground conductor of the second transmission line in the region of the first and second transmission lines facing each other is increased to g4, and the height of the conductive bump is increased. Is h, the gap g1
ＧG4 is set as g3-g1４−g4-g2ｈ2.5h to form a flip-flop mounting structure.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] FIGS. 1A and 1B are diagrams for explaining a flip chip mounting structure according to a first embodiment of the present invention, wherein FIG. 1A is a perspective view thereof, and FIG. ) Is a sectional view taken along line bb, (c) is a sectional view taken along line cc in (b), and (d) is a sectional view taken along line dd in (b).

The transmission line 10 having the coplanar structure has a characteristic impedance Zo of 50Ω and a signal line conductor 11 having a width of 50Ω.
μm, input portion 1 between signal line conductor 11 and ground conductor 12
6, the gap g1 is 35 μm, the relative permittivity of the insulator substrate 13 is 12.5, and the thickness is 150 μm. In addition, the portion where the conductive bumps 14 and 24 are located (the portion opposite to the input portion 16, that is, the region portion 1 facing the other transmission path 20).
In the opposing portion of the signal line conductor 11 and the ground conductor 12 corresponding to (5), the gap g3 is set to “g1 <g3”, and the gap is widened by “g3−g1 = Δg”.

A transmission line 20 having a ground coplanar structure
Has a characteristic impedance of 50Ω, a width of the signal line conductor 21 of 50 μm, a gap g2 of the output portion 26 between the signal line conductor 21 and the ground conductor 22 of 35 μm, a relative permittivity of the insulator substrate 23 of 12.6, The thickness is 600 μm. Also,
The opposing portions of the signal line conductor 21 and the ground conductor 22 corresponding to the portions where the conductive bumps 14 and 24 are located (the portion opposite to the output portion 26, that is, the region portion 25 facing the other transmission path 10) The gap g4 is set to “g2 <g4”, and the gap is expanded by “g4−g2 = Δg”.

The transmission line 10 extends in the upper left direction on the paper surface of FIG. 1A, and the transmission line 20 extends in the lower right direction. Here, only the connection portion is shown. The other (b) to (d) also show only the connection part.

Here, the conductive bumps 14 and 24 having a height h of 50 μm are used. The conductive bumps 14 are provided between the signal line conductors 11 and 21 of the transmission line 10 and the transmission line 20. The conductive conductor bumps 24 connect between the ground conductors 12 and 22 respectively.

[0012] From the input section 16 of the transmission line 10 to the transmission line 2
FIG. 2 shows the relationship between the height h of the conductive bumps 14 and 24 and the gap expansion width Δg for setting the characteristic impedance Zo of the transmission line up to the zero output section 26 to 50Ω, 60Ω and 70Ω. For any characteristic impedance,
When the height h of the conductive bump is about 30 μm to 150 μm, Δg / h has a slope of about 2.5. Note that, as described above, Δg = g3-g1 = g4-g2.

When the height h of the conductive bump is 50 μm,
When trying to obtain a characteristic impedance of 50Ω, Δg
From the relationship of /h=2.5, the expansion width Δg is 125 μm, and the gaps g3 and g4 of the transmission line 10 are g3 = g1 + Δg = 35 μm + 125 μm = 160 μm g4 = g2 + Δg = 35 μm + 125 μm = 160 μm. Thus, the transmission line 1 having the coplanar structure
The characteristic impedance from the input section 16 of 0 to the output section 26 of the transmission line 20 of the ground coplanar structure is 5
It becomes possible to match to 0Ω.

When the characteristic impedance Zo is 60Ω or 70Ω, the conductive bumps 14, 2
If the height h of No. 4 is 30 μm or more, Δg / h is about 2.
5, so the expansion width Δg is found in the same manner as above,
The gaps g3 and g4 may be set. In the present structure, the ground conductors 12 and 22 are connected to each other by using two bumps 24 as one set. However, it is needless to say that three or more bumps can be connected as one set. It is.

FIG. 3 is a diagram showing the structure of the transmission line 20 having the grant coplanar structure from the input portion 16 of the transmission line 10 having the coplanar structure.
FIG. 7 is a diagram illustrating frequency characteristics of reflection loss of a path leading to an output unit 26 of FIG. This structure (expansion width Δg = 125 μm)
Is 40 dB or more over a wide band of 40 GHz as compared with the conventional structure having the expansion width Δg = 0, and the frequency characteristics are significantly improved.

FIG. 4 is a diagram showing a structure of the transmission line 20 having the grant coplanar structure from the input portion 16 of the transmission line 10 having the coplanar structure.
FIG. 7 is a diagram illustrating frequency characteristics of insertion loss of a path leading to an output unit 26 of FIG. In this structure, no loss is observed over a wide band of 40 GHz, which indicates that the characteristics are significantly improved as compared with the conventional structure.

FIGS. 5A and 5B are views for explaining a flip chip mounting structure according to a modification, in which FIG.
(B) is a sectional view taken along line bb of (a), (c) is c of (b).
FIG. 3D is a cross-sectional view taken along the line c, and FIG. 4D is a cross-sectional view taken along the line d-d in FIG.

In FIG. 5, the structure of the change in the gap between the signal line conductor and the ground conductor in the regions 35 and 45 where the two transmission lines are not opposed to each other is defined as the structure between the gaps g1 and g3. Tapers 37, 47 are formed in the ground conductors 32, 42 so that the change, the change between g2 and g4, becomes slower, respectively. Fig. 1
This is exactly the same as that described above.

[Second Embodiment] FIGS. 6 and 7 are views for explaining a flip-chip mounting structure according to a second embodiment. FIG. 6A is a perspective view of FIG. 6B is a sectional view taken along the line bb of FIG. 6A, FIG. 7A is a sectional view taken along the line aa of FIG. 6B, and FIG. b
It is a -b line sectional view.

Here, an example is shown in which a transmission line 50 having a coplanar structure is flip-chip connected to a transmission line 60 having a ground coplanar structure which also serves as an input / output unit by using bump electrodes. Electronic components are mounted on the transmission line 50 to form an electric circuit.
The signal input to the transmission line 8 is processed by this electric circuit and then output from the output unit 66 of the transmission circuit 60. However, the electric circuit in the transmission line 50 is described above because the description is limited to the connection part. Absent.

The transmission line 50 has a characteristic impedance of 5
0 Ω, the width of the signal line conductor 51 is 50 μm,
The gap g1 between the conductor and the ground conductor 52 is 35 μm, the relative permittivity of the insulator substrate 53 is 12.5, and the thickness is 150 μm. The gap g3 of the opposing portion between the signal line conductor 51 and the ground conductor 52 corresponding to the portion where the conductive bumps 54 and 64 are located (region portions 55 and 57 facing the other transmission path 60) is "g1 <g3". Is set and the gap is
3-g1 = Δg ”.

The transmission line 60 has a characteristic impedance of 50 Ω serving also as the input section 68 and the output section 66, the width of the signal line conductor 61 divided at the center is 50 μm, and the transmission line 60 between the signal line conductor 61 and the ground conductor 62. The gap g2 is 35 μm,
The dielectric substrate 63 has a relative dielectric constant of 12.6 and a thickness of 600 μm.
m. The gap g4 between the signal line conductor 61 and the ground conductor 62 corresponding to the portion where the conductive bumps 54 and 64 are located (the region portions 65 and 67 facing the other transmission path 50) is "g1 <g4". Is set, and the gap is widened by “g4−g1 = Δg”.

As described above, the input section 68 of the transmission line 60
In order to match the characteristic impedance from the output line 66 to the output section 66, the gap width Δ in the regions 55, 57, 65, 67 where the two transmission lines 50, 60 face each other.
g is obtained by Δg / h =
Determine based on 2.5. Thus, the transmission line 5
The gap g3 of the transmission line 60 and the gap g4 of the transmission line 60 are set to 160 μm, respectively.
The characteristic impedance from the input unit 68 to the output unit 66 can be matched to 50Ω.

In this structure, two portions connecting the transmission lines 50 and 60 are connected by one set of bumps.
A set of three or more may be used. Similar to the description of FIG. 5 described above, a similar effect can be obtained even if a taper is provided in a portion where the gap changes and the change is made slower.

[Other Embodiments] In the first and second embodiments described above, the connection structure between the transmission line having the coplanar structure and the transmission line having the ground coplanar structure has been described. The same operation and effect can be obtained even when the transmission lines are connected to each other or when the transmission lines having the ground coplanar structure are connected to each other.

[0026]

As described above, according to the present invention, the reactance component due to the capacitive coupling between the signal line conductor and the ground conductor of the two transmission lines can be reduced, and the path from the input section to the output section can be reduced. The characteristic impedance can be matched, and the signal transmission characteristics particularly in an ultra-high frequency range of several tens of GHz or more are greatly improved.

[Brief description of the drawings]

FIGS. 1A and 1B are views for explaining a flip-chip mounting structure according to a first embodiment of the present invention, wherein FIG. 1A is a perspective view thereof, and FIG. 1B is a cross-sectional view taken along line bb of FIG. FIG. 2C is a cross-sectional view taken along line cc of FIG. 2B, and FIG. 2D is a cross-sectional view taken along line dd of FIG.

FIG. 2 is a diagram showing a relationship between a height h of a conductive bump and a width Δg of a gap for obtaining a specific characteristic impedance.

FIG. 3 is a diagram illustrating frequency characteristics of return loss.

FIG. 4 is a diagram illustrating frequency characteristics of insertion loss.

5A and 5B are views for explaining a flip chip mounting structure showing a modification of the first embodiment, wherein FIG. 5A is a perspective view thereof, and FIG. 5B is a cross-sectional view taken along line bb of FIG. FIG. 2C is a cross-sectional view taken along line cc of FIG. 2B, and FIG. 2D is a cross-sectional view taken along line dd of FIG.

6A and 6B are views for explaining a flip-chip mounting structure according to the second embodiment, wherein FIG. 6A is a perspective view thereof, and FIG. 6B is a sectional view taken along line bb of FIG. .

7A and 7B are views for explaining a flip-chip mounting structure according to a second embodiment, in which FIG. 7A is a cross-sectional view taken along line aa of FIG. 6B, and FIG. B- of (b)
It is a sectional view taken on line b.

8A and 8B are views for explaining a conventional flip chip mounting structure, wherein FIG. 8A is a perspective view thereof, and FIG.
(C) is a cross-sectional view taken along line cc of (b),
(D) is a sectional view taken along line dd of (b).

[Explanation of symbols]

10, 30, 50, 70: Planar structure transmission line 20, 40, 60, 80: Ground coplanar structure transmission line 11, 21, 31, 41, 51, 61, 71, 81: Signal line conductor 12, 22, 32, 42, 52, 62, 72, 82: ground conductors 13, 23, 33, 43, 53, 63: insulator substrate 14, 24, 34, 44, 54, 64, 74, 84: conductive bumps 15, 25, 35, 45, 55, 57, 65, 67, 7
5, 85: area where transmission lines face each other 16, 36, 68, 76: input section 26, 46, 66, 86: output section 37, 47: taper

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-291140 (JP, A) JP-A-6-120302 (JP, A) JP-A-7-74285 (JP, A) JP-A-7-74 240482 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/60 H01L 23/12 H01P 3/08 H01P 5/08

Claims (1)

(57) [Claims] A first transmission line having a coplanar structure or a ground coplanar structure in which a gap between a signal line conductor and a ground conductor formed on the same surface as the signal line conductor is g1;
A second transmission line having a coplanar structure or a ground coplanar structure in which a gap between a signal line conductor and a ground conductor formed on the same surface as the signal line conductor is g2, and a signal line of the first and second transmission lines In a flip-chip mounting structure including a conductive bump for electrically connecting a conductor and a ground conductor to each other to electrically connect the first and second transmission lines to each other, A gap between the signal line conductor and the ground conductor is increased to g3, and a gap between the signal line conductor and the ground conductor of the second transmission line in a region of the first and second transmission lines facing each other. G4, and when the height of the conductive bump is h, the gaps g1 to g4 are set as g3-g1 ≒ g4-g2 ≒ 2.5h. Flop mounting structure.