JP2020195018A - Communication module - Google Patents

Abstract

To enable performance improvement in transmission characteristics of a communication module.SOLUTION: A communication module 1 comprises: a first substrate 10; a second substrate 20 having a dielectric constant and dielectric loss which are lower than those of the first substrate 10; and a communication integrated circuit 30 having a first terminal 31 which is electrically connected to a first pad 10A formed on the first substrate 10 and a second terminal 32 which is electrically connected to a second pad 20A formed on the second substrate 20. As the second terminal 32, the communication integrated circuit 30 has a transmitting/receiving terminal 32a connected to an antenna 40 and a ground terminal 32b provided adjacent to the transmitting/receiving terminal 32a. The second pad 20A connected to the transmitting/receiving terminal 32a is electrically connected to antenna transmission lines 41 and 42, while the second pad 20A connected to the ground terminal 32b is electrically connected to a ground pattern.SELECTED DRAWING: Figure 1

Description

The present invention relates to a communication module.

The following Patent Document 1 discloses a communication module in which a communication integrated circuit such as an RFIC is mounted on a multilayer board. Some of the terminals of the communication integrated circuit are connected to the first substrate having a large thermal conductance among the multilayer boards, and the other terminals of the communication integrated circuit have a smaller thermal conductance than the first substrate. It is connected to the second board. According to this configuration, the heat of the communication integrated circuit can be released to the first substrate having a large thermal conductance, so that the influence of the heat on the second substrate having a small thermal conductance can be reduced. That is, by forming the antenna on the second substrate, it is possible to prevent the transmission characteristics of the communication module from being deteriorated due to the influence of heat.

JP-A-2019-36587

In the above-mentioned communication module of the prior art, sufficient transmission characteristics have been obtained by reducing the influence of heat, but with the progress of technology, further improvement in transmission characteristics has been required in recent years. ..

An object of the present invention is to improve the performance of the transmission characteristics of a communication module in order to meet the above requirements.

(1) The communication module according to one aspect of the present invention includes a first substrate, a second substrate having a smaller dielectric constant and dielectric loss than the first substrate, and a first substrate formed on the first substrate. An integrated circuit for communication having a first terminal electrically connected to one pad and a second terminal electrically connected to a second pad formed on the second substrate. The communication integrated circuit has, as the second terminal, a transmission / reception terminal connected to the antenna and a ground terminal provided adjacent to the transmission / reception terminal, and is connected to the transmission / reception terminal. The second pad was electrically connected to an antenna transmission path formed on the second substrate, and the second pad connected to the ground terminal was formed on the second substrate. It is electrically connected to the ground pattern.

(2) The communication module according to (1) above, wherein the second substrate is a first surface on which the communication integrated circuit is mounted and a surface opposite to the first surface. The first surface having a second surface on which the antenna is formed and a first opening formed inside the mounting area of the communication integrated circuit and penetrating from the first surface to the second surface. The substrate is a concave portion to which the second surface of the second substrate is joined, and a convex portion formed inside the concave portion and fitted to the first opening to be connected to the first terminal. And may have.
(3) In the communication module according to (2) above, the second substrate is a notched portion cut out from the outer peripheral edge of the second substrate toward the mounting region of the communication integrated circuit. The first substrate may have a fitting portion that fits into the notch portion.
(4) In the communication module described in (3) above, a second opening may be formed in the fitting portion.
(5) The communication module according to (4) above, which is attached via the second opening and may include a heat radiating plate that dissipates heat from the integrated circuit for communication.

According to the above aspect of the present invention, it is possible to realize high performance of the transmission characteristics of the communication module.

It is a plane schematic diagram of the communication module which concerns on 1st Embodiment of this invention. It is sectional drawing of the arrow view AA of the communication module shown in FIG. It is a plane schematic diagram of the communication module which concerns on 2nd Embodiment of this invention. It is sectional drawing of the arrow view BB of the communication module shown in FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(First Embodiment)
FIG. 1 is a schematic plan view of the communication module 1 according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along the line AA of the communication module 1 shown in FIG.
As shown in FIG. 1, the communication module 1 includes a first substrate 10, a second substrate 20, a communication integrated circuit 30, and an antenna 40.

As shown in FIG. 1, the first substrate 10 is formed in a rectangular shape in a plan view. As shown in FIG. 2, the first substrate 10 is a rigid substrate formed thicker than the second substrate 20. The first substrate 10 has a higher thermal conductance than the second substrate 20. Further, the first substrate 10 has a larger dielectric constant (Dk) and dielectric loss (Df) than the second substrate 20.

As shown in FIG. 1, the second substrate 20 may be referred to as a third surface 11 of the first substrate 10 (distinguishable from the first surface 21 and the second surface 22 of the second substrate 20 described later). It is housed in the recess 13 formed in (good) and is joined to the first substrate 10. As shown in FIG. 2, the second substrate 20 is a flexible printed circuit board formed thinner than the first substrate 10. The second substrate 20 has a smaller thermal conductance than the first substrate 10. Further, the second substrate 20 has a smaller dielectric constant (Dk) and a smaller dielectric loss (Df) than the first substrate 10.

The material of the second substrate 20 is not particularly limited as long as the dielectric constant (Dk) and the dielectric loss (Df) of the second substrate 20 are smaller than those of the first substrate 10. For example, if the material of the first substrate 10 is FR4 (glass epoxy), the material of the second substrate 20 may be LCP (liquid crystal polymer). As an example, FR4 has a dielectric constant of 4.8 and a dielectric loss of 0.072, and LCP has a dielectric constant of 2.9 and a dielectric loss of 0.0058.

As shown in FIG. 1, the communication integrated circuit 30 is mounted on the central portion of the second substrate 20 (also the central portion of the first substrate 10 or the central portion of the communication module 1) in a plan view. The communication integrated circuit 30 is formed of, for example, an RFIC (radio frequency integrated circuit) BGA package or the like. On the lower surface of the communication integrated circuit 30, a first terminal 31 electrically connected to a first pad 10A formed on the first substrate 10 and a second terminal 31 formed on the second substrate 20 A second terminal 32, which is electrically connected to the pad 20A, is provided. In the figure, not all terminals and pads of the communication integrated circuit 30 are shown, and some terminals and pads are omitted. Further, the number of terminals of the communication integrated circuit 30 is not limited to the number shown in the figure.

The communication integrated circuit 30 has a transmission / reception terminal 32a connected to the antenna 40 and a ground terminal 32b provided adjacent to the transmission / reception terminal 32a as the second terminal 32. A plurality of transmission / reception terminals 32a are provided along the outer peripheral edge of the communication integrated circuit 30 (package) which is rectangular in a plan view, and the ground terminals 32b are arranged inside the area surrounded by the transmission / reception terminals 32a. It is provided one-to-one so as to be adjacent to the terminal 32a. In FIG. 1, the set of the transmission / reception terminal 32a and the ground terminal 32b adjacent thereto are surrounded by a dotted line.

The antenna 40 is a planar antenna, and is formed on a second surface 22 (see FIG. 2) opposite to the first surface 21 of the second substrate 20 on which the communication integrated circuit 30 is mounted. The antenna 40 is connected to an antenna transmission line 41 provided in the inner layer of the second substrate 20 via a conductor such as a via (not shown). Further, the antenna transmission line 41 is connected to the antenna transmission line 42 provided on the first surface 21 of the second substrate 20 via a conductor such as a via.

The antenna transmission line 42 is connected to the transmission / reception terminal 32a (communication integrated circuit 30) via the second pad 20A and the connection unit 60. The connecting portion 60 is, for example, a bump, a solder, a conductive paste, or the like. As shown in FIG. 1, the antenna 40 is two-dimensionally arranged around the communication integrated circuit 30. The antenna transmission line 42 extends substantially radially from the communication integrated circuit 30 toward the antennas 40 arranged around the antenna transmission line 42.

As shown in FIG. 2, the ground terminal 32b of the communication integrated circuit 30 is connected to the ground pattern 43 provided on the second substrate 20 via the second pad 20A. The ground terminal 32b and the second pad 20A are bumped, soldered, and conductive, similarly to the connecting portion 60 connecting the transmission / reception terminal 32a and the second pad 20A electrically connected to the antenna transmission line 42. It is connected via sex paste or the like.

The second substrate 20 includes a first surface 21 on which the above-mentioned integrated circuit for communication 30 is mounted, and a second surface 22 on the side opposite to the first surface 21 on which the above-mentioned antenna 40 is formed. It has a first opening 23 formed inside the mounting region 21a of the communication integrated circuit 30 and penetrating from the first surface 21 to the second surface 22.

As shown in FIG. 1, the mounting area 21a of the communication integrated circuit 30 refers to an area of the first surface 21 that overlaps with the communication integrated circuit 30 in a plan view. The first opening 23 is inside the mounting area 21a of the communication integrated circuit 30, and in the present embodiment, inside the area surrounded by the ground terminal 32b of the communication integrated circuit 30, it is rectangular in a plan view. It is open to the shape.

As shown in FIG. 2, the first substrate 10 is fitted into a recess 13 to which the second surface 22 of the second substrate 20 is joined, and a recess 13 formed inside the recess 13 and fitted into the first opening 23. It has a convex portion 14 connected to the first terminal 31. The recess 13 is joined to the second surface 22 of the second substrate 20 via the joining material 61 shown in FIG. That is, the first substrate 10 is joined in the oscillation direction of the antenna 40 of the second substrate 20. The recess 13 is a recess formed on the surface 11 of the first substrate 10 and has a depth corresponding to the thickness of the second substrate 20.

The first surface 21 of the second substrate 20 housed in the recess 13 forms the same plane as the surface 11 of the first substrate 10 (the top surface of the convex portion 14 is also the same). As shown in FIG. 1, other electronic components 50 such as resistors, capacitors, oscillators, inductors, and connectors are mounted on the surface 11 of the first substrate 10. By making the first surface 21 of the second substrate 20 and the surface 11 of the first substrate the same surface, the communication integrated circuit 30 and other electronic components 50 can be easily mounted by reflow mounting or the like. ..

In the communication module 1, the first substrate 10 is formed with an electronic circuit whose circuit characteristics are not easily affected by the dielectric loss of the substrate. Specifically, an electronic circuit excluding the above-mentioned antenna 40 and antenna transmission lines 41, 42 and the like is formed. As shown in FIG. 2, this electronic circuit includes a signal transmission path 51 and a heat dissipation via 52 formed in the convex portion 14. The heat radiating via 52 extends to the back surface 12 of the first substrate 10 (the first surface 21 and the second surface 22 of the second substrate 20, and further, the surface 11 may be distinguished from the surface 11). It also functions as a ground pattern for the second substrate 20.

The signal transmission line 51 and the heat radiation via 52 are connected to the first terminal 31 of the communication integrated circuit 30 via the first pad 10A on the top surface of the convex portion 14. Each of the signal transmission line 51, the heat dissipation via 52, and the first pad 10A has bumps, solder, and a conductive paste, similarly to the connecting portion 60 connecting between the second terminal 32 and the second pad 20A. It is connected via such as.

As shown in FIG. 1, the second substrate 20 communicates from a set of sides facing each other among the four sides of the outer peripheral edge of the second substrate 20 (temporarily, the four sides when there is no notch 24 described later). It has a notch 24 notched toward the mounting region 21a of the integrated circuit 30. The cutout portion 24 is formed in a trapezoidal shape in a plan view, and the width gradually becomes narrower (tapered) toward the mounting region 21a. The notch 24 is formed so as to avoid the antenna 40 and the antenna transmission line 42 extending radially.

The first substrate 10 has a fitting portion 15 that fits into the notch portion 24. The fitting portion 15 is formed in a trapezoidal shape in a plan view, similarly to the notch portion 24. The fitting portion 15 forms a part of the surface 11 of the first substrate 10 and also forms a part of the side wall surface of the recess 13 of the first substrate 10. As a result, the side wall surface of the recess 13 has substantially the same shape as the outer peripheral edge of the second substrate 20 on which the notch 24 is formed in a plan view.

According to the communication module 1 having the above configuration, the first substrate 10, the second substrate 20 having a smaller dielectric constant and dielectric loss than the first substrate 10, and the first substrate 10 connected to the first substrate 10. A communication integrated circuit 30 having a terminal 31 and a second terminal 32 connected to the second substrate 20 is provided, and the communication integrated circuit 30 is connected to the antenna 40 as the second terminal 32. Since the transmission / reception terminal 32a and the ground terminal 32b provided adjacent to the transmission / reception terminal 32a are provided, the transmission characteristics of the communication module 1 can be improved.
If the ground terminal 32b is connected to the ground pattern (radiation via 52) of the first substrate 10 instead of the ground pattern 43 of the second substrate 20, the heat radiation via 52 is the ground pattern 43 of the second substrate 20. Since they are not necessarily at the same potential, there is a concern that the transmission characteristics of the antenna 40 may deteriorate. Therefore, it is necessary to form a connecting layer (conductive layer) for making the ground patterns of the first substrate 10 and the second substrate 20 at the same potential.
On the other hand, according to the above configuration, since the transmission / reception terminal 32a of the communication integrated circuit 30 and the ground terminal 32b adjacent thereto are connected to the same second substrate 20, the above-mentioned concern can be resolved. Further, there is no need for additional processing of the connection layer described above.

Further, as in the present embodiment, only the transmission / reception terminal 32a of the communication integrated circuit 30 and the ground terminal 32b adjacent thereto are connected to the second board 20, and the other terminals are connected to the first board 10. Therefore, the antenna region and the other signal region can be materially separated. For example, a low-dielectric material that improves the transmission characteristics of the antenna 40 can be selected for the second substrate 20, a material that can be easily multilayered can be selected for the first substrate 10, and an optimum material can be selected depending on the region. .. Further, by separating the materials, the area or volume of the second substrate 20 of the low-dielectric material can be minimized, and the cost can be reduced.

Further, in the present embodiment, the second substrate 20 is a first surface 21 on which the communication integrated circuit 30 is mounted and a second surface opposite to the first surface 21 on which the antenna 40 is formed. 22 and a first opening 23 formed inside the mounting region 21a of the communication integrated circuit 30 and penetrating from the first surface 21 to the second surface 22, and the first substrate 10 is a second. It has a concave portion 13 to which the second surface 22 of the substrate 20 is joined, and a convex portion 14 formed inside the concave portion 13 and fitted to the first opening 23 to be connected to the first terminal 31. doing. According to the above configuration, the first terminal 31 and the first substrate 10 can be three-dimensionally connected inside the mounting area 21a of the communication integrated circuit 30. As a result, the length of the first substrate 10 in the plane direction can be shortened, the component mounting density can be increased, and the size of the communication module 1 can be contributed.

Further, according to the above configuration, since the first substrate 10 (rigid substrate) is joined in the oscillation direction of the antenna 40 of the second substrate 20 (flexible printed circuit board), bending deformation of the antenna 40 can be suppressed. Can be done. As a result, the transmission characteristics of the antenna 40 can be stabilized and the band of the antenna 40 can be widened. Further, since the convex portion 14 of the first substrate 10 is connected to the first terminal 31 in the central region of the communication integrated circuit 30 that easily becomes a heat spot in a plan view, the first substrate having a large thermal conductance The heat of the communication integrated circuit 30 can be efficiently dissipated to 10. In addition, since the convex portion 14 of the first substrate 10 fits into the first opening 23 of the second substrate 20, the positioning of the second substrate 20 with respect to the first substrate 10 becomes easy. The communication module 1 can be easily assembled and the yield can be improved.

Further, in the present embodiment, the second substrate 20 has a notch portion 24 cut out from the outer peripheral edge of the second substrate 20 toward the mounting region 21a of the communication integrated circuit 30, and is the first substrate. Reference numeral 10 denotes a fitting portion 15 that fits into the notch portion 24. According to the above configuration, the rotation of the second substrate 20 with respect to the first substrate 10 around the convex portion 14 can be regulated by fitting the notch portion 24 and the fitting portion 15. As a result, the positioning of the second substrate 20 with respect to the first substrate 10 becomes easier, the communication module 1 can be easily assembled, and the yield can be further improved.

(Second Embodiment)
Next, the second embodiment of the present invention will be described. In the following description, the same or equivalent configurations as those in the above-described embodiment are designated by the same reference numerals, and the description thereof will be simplified or omitted.

FIG. 3 is a schematic plan view of the communication module 1 according to the second embodiment of the present invention. FIG. 4 is a schematic cross-sectional view taken along the line BB of the communication module 1 shown in FIG.
As shown in FIG. 3, in the first substrate 10 of the second embodiment, the second opening 16 is formed in the fitting portion 15 described above. The second opening 16 penetrates from the front surface 11 to the back surface 12 of the first substrate 10. The second openings 16 are formed in pairs at positions sandwiching the communication integrated circuit 30.

When assembling the communication module 1, a jig (not shown) for fixing the first substrate 10 is inserted into the second opening 16. This facilitates, for example, joining the second substrate 20 to the first substrate 10, mounting the communication integrated circuit 30, and other electronic components 50.
Further, the second opening 16 becomes a mounting hole for a heat radiating plate 70 that dissipates heat from the communication integrated circuit 30 after the communication module 1 is assembled. The heat radiating plate 70 has a pair of support columns 71 inserted into the pair of second openings 16, and is erected so as to be in contact with the upper surface of the communication integrated circuit 30 (see FIG. 4).

Further, as shown in FIG. 3, a third opening (through hole 17 formed in the first substrate 10 and a second substrate 20) is formed through the first substrate 10 and the second substrate 20. (Those through which the through holes 25 are communicated) may be formed. By forming such a third opening and inserting a jig, positioning and joining of the second substrate 20 with respect to the first substrate 10 becomes easier.

Further, as shown in FIG. 3, an electromagnetically shielded ground via 54 is formed along the outer peripheral edge of the second substrate 20, and a recess 13 of the first substrate 10 along the outer peripheral edge of the second substrate 20 is formed. An electromagnetically shielded ground via 53 may be formed along the opening edge of the. Further, the ground via 54 of the second substrate 20 and the ground via 53 of the first substrate 10 may be connected by a conductor layer 55 such as solder. As a result, the ground potentials of the ground via 54 of the second substrate 20 and the ground via 53 of the first substrate 10 can be stabilized. If each of the ground vias 54 is connected inside the second substrate 20 and each of the ground vias 53 is connected inside the first substrate 10, the conductor layer 55 will be as shown in FIG. It is not necessary to connect all the ground vias 53 and 54. Further, if the printing mask is designed so that the ground vias 53 and 54 get wet with solder in the process of reflow mounting the communication integrated circuit 30 and other electronic components 50, the ground vias 53 and 54 can be easily electrically mounted. Since it can be connected to, the formation of the conductor layer 55 becomes easy.

Although preferred embodiments of the present invention have been described and described above, it should be understood that these are exemplary of the present invention and should not be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the invention. Therefore, the present invention should not be considered limited by the above description, but is limited by the claims.

1 ... Communication module, 10 ... First board, 10A ... First pad, 13 ... Concave, 14 ... Convex part, 15 ... Fitting part, 16 ... Second opening, 20 ... Second board, 20A ... 2nd pad, 21 ... 1st surface, 21a ... Mounting area, 22 ... 2nd surface, 23 ... 1st opening, 24 ... Notch, 30 ... Communication integrated circuit, 31 ... 1st terminal, 32 ... 2nd terminal, 32a ... Transmission / reception terminal, 32b ... Ground terminal, 40 ... Antenna, 41 ... Antenna transmission line, 42 ... Antenna transmission line, 43 ... Ground pattern, 70 ... Heat dissipation plate

Claims (5)

The first board and
A second substrate having a smaller dielectric constant and a smaller dielectric loss than the first substrate,
A first terminal electrically connected to a first pad formed on the first substrate and a second terminal electrically connected to a second pad formed on the second substrate. And, with an integrated circuit for communication,
The communication integrated circuit has, as the second terminal, a transmission / reception terminal connected to the antenna and a ground terminal provided adjacent to the transmission / reception terminal.
The second pad connected to the transmission / reception terminal is electrically connected to an antenna transmission line formed on the second substrate.
A communication module characterized in that the second pad connected to the ground terminal is electrically connected to a ground pattern formed on the second substrate. The second substrate includes a first surface on which the communication integrated circuit is mounted, a second surface on the side opposite to the first surface on which the antenna is formed, and the communication integrated circuit. It has a first opening formed inside the mounting region and penetrating from the first surface to the second surface.
The first substrate is connected to a recess to which the second surface of the second substrate is joined, and a recess formed inside the recess, fitted into the first opening, and connected to the first terminal. The communication module according to claim 1, wherein the communication module has a convex portion. The second substrate has a notch portion cut out from the outer peripheral edge of the second substrate toward the mounting region of the communication integrated circuit.
The communication module according to claim 2, wherein the first substrate has a fitting portion that fits into the notch portion. The communication module according to claim 3, wherein a second opening is formed in the fitting portion. The communication module according to claim 4, further comprising a heat radiating plate which is attached through the second opening and dissipates heat from the integrated circuit for communication.

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