JP3426878B2 - Wiring board 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 wiring board mounting structure, and more particularly to a semiconductor element housing package suitable for housing or mounting high frequency semiconductor elements in the microwave band to millimeter wave band region. The present invention relates to a mounting structure for mounting a wiring board such as a wiring board or a multilayer wiring board on an external electric circuit board while reducing transmission loss of high frequency signals.

[0002]

2. Description of the Related Art In recent years, in the age of advanced information technology, it has been considered to use radio waves used for information transmission from a microwave range of 1 to 30 GHz to a millimeter range of 30 to 300 GHz. For example, an inter-vehicle radar
Various application systems using millimeter-waves, such as an office high-speed data communication system (wireless LAN), have also been proposed.

A wiring board for housing or mounting a high frequency semiconductor element used in such an application system,
For example, a semiconductor element housing package in which the semiconductor element is housed and hermetically sealed in a space formed by an insulating base body made of a dielectric material and a frame body, and a high frequency terminal is insulated and hermetically sealed is provided. Proposed.

However, for inputting / outputting a high-frequency signal to the package for accommodating a semiconductor element having the above-described structure and mounting it on an external electric circuit board, a signal transmission line such as a strip line electrically connected to the semiconductor element for high frequency is used. It is drawn from the inside of the space to the outside through the frame, and is further arranged on the bottom surface via the side surface of the insulating substrate, and the high frequency terminal of the package for housing the semiconductor element and the wiring layer of the external electric circuit board are wired or ribboned. Therefore, there is a problem in mass productivity and cost reduction during module manufacturing.

In order to solve such a problem, surface mounting type semiconductor element accommodating packages are collectively packaged by reflow, and a semiconductor element and a signal transmission line are connected using a through hole or the like to propagate a high frequency signal. It is thought that this is because the impedance mismatch at the connection between the wiring layer of the package and the through hole and the discontinuous change of the electromagnetic field distribution due to the high frequency signal are caused. There is a risk that the radiation loss will be large and the characteristics of the high frequency signal will be easily deteriorated.

In order to alleviate the discontinuity of the electromagnetic field distribution due to the signal at the connection between the wiring layer of the semiconductor element housing package and the through hole, the through hole is obliquely formed to form the wiring layer and the through hole. It may be possible to make the angle obtuse, but there is a problem in workability and mass productivity.

Therefore, as shown in FIG.
The signal transmission line 16, on the storage surface side of the
A semiconductor element housing package in which 17 is formed and the high frequency signal input / output portion is electromagnetically coupled through a slot hole 19 provided in the ground layer 18 provided inside the insulating substrate 15 is conceivable. When mounting the package for external electrical circuit board 20, the signal transmission line 17 formed on the bottom surface of the package is mounted on the wiring layer 2 of the external electrical circuit board 20.
1 and is connected by soldering or the like.

[0008]

However, in the above-mentioned mounting structure, depending on the frequency of the signal, reflection may occur at the connecting portion of the mounting portion, resulting in a large signal transmission loss or difficulty in signal transmission itself. There were challenges.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to mount an external electric circuit on a wiring board for accommodating or mounting a high frequency semiconductor element on the external electric circuit board. A semiconductor element housing package, multilayer wiring board, etc. suitable for housing or mounting a high frequency semiconductor element capable of surface mounting on a board and reducing transmission loss of high frequency signals are mounted on an external electric circuit board. It is to provide a mounting structure of a wiring board.

[0010]

In view of the above-mentioned problems, the inventors of the present invention have made repeated studies on a structure which enables surface mounting on an external electric circuit board without causing deterioration of characteristics of high frequency signals. One signal transmission line is formed on the surface of the insulating substrate on the mounting side of the element, the other signal transmission line is not formed on the bottom surface of the insulating substrate, and the wiring layer formed on the external electric circuit board is used to transmit the other signal. It was found that the transmission loss of a high frequency signal at the time of surface mounting can be reduced by using a line and electromagnetically coupling them, and the present invention has been completed.

[0011] In other words, the mounting structure of the wiring substrate of the present invention, induction
Stores or mounts semiconductor elements that use an electrical insulator as an insulating substrate.
On the surface of the wiring board for mounting,
To form a first signal transmission line for electrically connecting
A ground layer having slot holes in the insulating substrate
An external electrical circuit to form the
The wiring layer formed on the circuit board is used as the second signal transmission line.
Slot holes in the ground layer formed on the wiring board
Via the first signal transmission line and the second signal transmission line
Electromagnetic waves without the need to provide a connection part with an adhesive such as solder
The wiring board to the external electrical circuit board
It is characterized by being mounted on a line layer .

Further, the wiring board is provided with a frame body integrally formed with the insulating base body for forming a space for accommodating the semiconductor element therein, or a semiconductor element mounted on the insulating base body has a concave lid. The package is a package for housing a semiconductor device, which is sealed inside by a body.

Further, although the signal transmission line may be made of tungsten (W), palladium (Pd), Ag, Cu, Au, etc., it is particularly formed of at least one of Ag, Cu, Au, It is characterized in that a signal having a frequency of 10 GHz or higher is transmitted.

It is desirable that the insulating substrate and the signal transmission line be manufactured by simultaneous firing.

[0015]

According to the present invention, a first signal transmission line electrically connected to a semiconductor element accommodated or mounted in a wiring board having a dielectric material as an insulating base, and an external surface mounting the wiring board. The wiring layer formed on the surface of the electric circuit board is electromagnetically coupled with the second signal transmission line so as to form a pair of signal transmission lines for transmitting a high-frequency signal, so that the first signal of the insulating substrate is formed. There is no connection part between the transmission line and the second signal transmission line composed of the wiring layer of the external electric circuit board by an adhesive such as solder, so that the transmission loss of the signal can be further reduced and the necessary high frequency signal can be passed. It becomes possible to transmit.

Further, by using a conductor material having a small electric resistance such as Ag, Cu or Au for the signal transmission line through which the high frequency signal is transmitted, the loss of the high frequency signal can be further reduced, and further, these conductor materials are used. When used for forming the signal transmission line, if the dielectric material constituting the insulating substrate, the frame body, etc. is made of a glass ceramic material, it can be co-fired with the transmission line, and its mass productivity can be improved, so that it can be used as a wiring board. It can also be manufactured at low cost.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The wiring board mounting structure of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a mounting structure in which a wiring board of the present invention is applied to a package for housing a semiconductor element, a semiconductor element for high frequency is housed and surface-mounted on an external electric circuit board.

In FIG. 1, reference numeral 1 denotes an insulating substrate 2, a frame body 10 for forming a space 9 for accommodating a semiconductor element 3,
First signal transmission line 4 formed on the surface of the insulating base 2.
And a ground layer 6 having a slot hole 5 provided inside the insulating substrate 2, which is a wiring board forming a semiconductor element housing package. The wiring board 1 is an external electric circuit board 7
Surface-mounted on the wiring layer formed on the wiring layer, and the wiring layer forms the second signal transmission line 8.

Inside the insulating substrate 2, a ground layer 6 made of a conductor layer is formed on almost the entire surface, and inside the ground layer 6, a slot hole 5 in which the conductor layer is not formed is formed. The signal transmission line 4 and the second signal transmission line 8 are formed via the slot holes 5 such that the ends of the lines face each other and are electromagnetically coupled to each other to transmit a signal with small loss. A plurality of slot holes 5 may be formed in the ground layer 6.

According to the present invention, the first signal transmission line 4 formed in the void 9 is formed by a combination of well-known transmission lines. For example, a microstrip line, a strip line, or a coplanar line is used. A line and a coplanar line with ground are formed on the surface of the insulating base 2.

A lid 11 is joined to the upper surface of the frame body 10 by metallization, glass or the like in order to protect the semiconductor element 3 housed in the cavity 9 from the external atmosphere, and thus the space 9 is formed. In order to prevent electromagnetic waves from leaking to the outside, the lid 11 is usually made of various ceramics, metal such as Ni / Co / Fe alloy, or insulating such as glass ceramics. It is also possible to dispose an electromagnetic wave absorbing substance such as carbon capable of absorbing an electromagnetic wave in the material, or to coat the surface with a composite material or the like in which the material is coated with a metal film such as Cu. is there.

FIG. 2 is a view for explaining the wiring in the void of the wiring board of FIG. 1, in which the semiconductor element 3 and the first signal transmission line 4 are formed in the void 9. Besides, a power supply layer 13 for supplying electric power to the semiconductor element 3 is formed, and one end of the microstrip conductor path and the power supply layer 13 are electrically connected to the semiconductor element 3 by a ribbon, a wire, a TAB, or the like. And the other end of the microstrip conductor path is connected to the slot hole 5 provided in the ground layer 6 formed in the insulating substrate 2 of the wiring board 1.
Is electromagnetically coupled to the second signal transmission line 8 which is a wiring layer of the external electric circuit board 7 via.

FIG. 3 shows a wiring board of the present invention applied to a package for accommodating a semiconductor element in which a semiconductor element mounted on an insulating substrate is sealed inside by a concave lid to be surface-mounted on an external electric circuit board. It is sectional drawing which shows the mounted structure. In the figure, reference numeral 12 is a concave lid, and other reference numerals are the same as those in FIG.

FIG. 4 is a cross-sectional view showing a mounting structure in which the wiring board of the present invention is applied to a multilayer wiring board in which semiconductor elements are directly connected to wiring electrodes on an insulating substrate and surface-mounted on an external electric circuit board. It is a figure, and the code | symbol in a figure is the same as the code | symbol of FIG. 1 like FIG.

1 to 4, the ends of the respective lines are overlapped with each other through the slot holes 5 formed in the ground layer 6 by a length corresponding to 1/2 wavelength of the required transmission signal frequency on average. It is desirable that the slot hole 5 be formed in such a position as to be a rectangular or elliptical elongated hole having a long side and a short side, and the shape specifies a frequency to be used and a bandwidth of the frequency. You can

Therefore, it is desirable that the long side of the slot hole 5 has a length corresponding to 1/2 wavelength of the transmission signal frequency, and the short side of the slot hole 5 has a length corresponding to 1/5 wavelength to 1/50.
It is desirable to set the length corresponding to the wavelength.

The semiconductor element 3 can be connected with a small transmission loss by directly housing or mounting it on the strip conductor path, but the method of connecting the conductor path and the semiconductor element 3 is not limited to this. For example, a gold ribbon or a plurality of wire bonds may be used for connection, or a conductor plate in which a conductor such as Cu is formed on a substrate such as polyimide may be used for connection.

The insulating substrate of the wiring board of the present invention is made of ceramics such as alumina (Al ₂ O ₃ ), glass ceramics, aluminum nitride (AlN), or an organic insulating material having organic resin as a constituent element. But,
In order to reduce the transmission loss of high frequency signals, it is desirable to use a low resistance conductor such as Ag, Cu or Au as the conductor of the signal transmission line. From this point, the insulating substrate has a firing temperature of about 800 to 1000 ° C. The glass-ceramic of (1) is most suitable, and this combination also enables simultaneous firing of the insulating substrate and the signal transmission line.

That is, by adopting the low resistance conductor as a signal transmission line, it is possible to reduce the conductor loss which increases in proportion to the square root of the conventional Al ₂ O when the frequency becomes higher.
It is possible to further reduce the conductor loss compared to the case of simultaneous firing with the combination of ₃ and W, especially when the frequency is 10 GH.
The effect becomes more remarkable in the region of z or more.

Next, in order to manufacture the wiring board of the present invention by the above combination, for example, a molding material prepared by mixing a raw material powder constituting glass ceramics with an organic binder is prepared by a doctor blade method or press molding. Law,
After a sheet-shaped molded body is obtained by a well-known molding method such as a rolling method, the sheet-shaped molded body is punched to form voids and through holes, and then a low resistance metal such as Ag, Cu or Au. A line pattern such as a signal transmission line or a ground layer pattern for forming a slot hole is formed by printing using a paste mainly composed of.

After that, a plurality of sheet-shaped compacts on which the required patterns are printed and formed are aligned and laminated, and the laminates are fired at a temperature of 800 to 1000 ° C. in a non-oxidizing atmosphere such as nitrogen. A wiring board is obtained by.

After the semiconductor element is adhered and fixed in a predetermined position with Au / Ge alloy or the like in the space of the wiring board thus obtained, it is electrically connected to the signal transmission line by wire bonding or a ribbon, and the upper surface of the frame body. A lid is adhered to the substrate by an Au / Si alloy to hermetically seal the semiconductor element in the cavity to form a semiconductor product, which is surface-mounted on an external electric circuit board made of a low loss material such as fluororesin. As a result, a semiconductor device is obtained.

[0033]

EXAMPLE In order to evaluate the transmission characteristics of high frequency signals in the mounting structure of the wiring board of the present invention, a glass ceramic material having a dielectric constant of 5.6 was used as the insulating substrate and the frame material, and the signal transmission line is shown in Table 1. The combination of the conductor material of low resistance metal shown in (1) and the combination of the insulating substrate and the frame material made of alumina material having a dielectric constant of 8.9 and W as the signal transmission line have a three-layer structure. An evaluation package was produced.

The electromagnetic coupling of this evaluation package employs a microstrip line as a signal transmission line connected to a semiconductor element, and becomes a stripline at the time of mounting through a slot hole formed in the ground layer in the insulating substrate. It should be connected to the wiring layer of the external electric circuit board.

As the external electric circuit board, a fluororesin board having a dielectric constant of 2.2 and a thickness of 1 mm was used.

On the other hand, in the evaluation package in which the signal transmission line is formed of a conductor material of low resistance metal, the frequency of the high frequency signal for evaluation is set to 20 GHz and 60 GHz,
For Hz, the line width of the signal transmission line of the evaluation package is 0.3 mm, the length of the portion protruding from the slot hole is 1.85 mm, and the dimension of the slot hole is 0.3 mm ×
The size was set to 4.0 mm square.

Similarly, for 60 GHz, the line width is 0.3 mm, the length of the portion protruding from the slot is 0.6 mm, and the size of the slot is 0.3 mm.
It was set to 1.3 mm square.

On the other hand, in the evaluation package in which the signal transmission line is formed by W, the frequency of the high frequency signal for evaluation is 60G.
And set the line width of the signal transmission line to 0.24 mm,
The length of the part protruding from the slot hole is 0.5 mm
The dimension of the slot hole was set to 0.2 mm × 1.0 mm square.

Further, for comparison, a conventional package having a signal transmission line for receiving a high frequency signal formed on the bottom surface of the package was made to have the same size as that of the evaluation package.

Each of the evaluation packages obtained as described above is used as 2
Individually, butted against the fluororesin board and mounted with solder,
Using a network analyzer, measure the transmission signal that entered the high frequency signal from the internal terminal of one evaluation package, passed through the wiring on the fluororesin substrate, and transmitted to the internal terminal of the other evaluation package, Power ratio S
21 parameters (dB) were calculated to evaluate the transmission loss of one high frequency terminal of the evaluation package.

[0041]

[Table 1]

As is clear from the results shown in Table 1, sample numbers 1, 3, 5, 7 of Comparative Examples, which are outside the scope of the claims of the present invention,
Since 9, 11, 13, 15, and 17 all have a transmission line for receiving a signal transmitted by electromagnetic coupling on the bottom surface of the wiring board, the transmitted signal is 20 GHz at −1.8 dB or less, 60 GHz at 60 GHz. -3.8 dB or less, the present invention does not have a transmission line for reception,
Sample numbers 2, 4, 6, 8 and 1 using low resistance conductors by electromagnetically coupling directly to the wiring layer on the external electric circuit board
For 0, 12, 14, and 16, the transmission is -1.
3 dB or more, -2.4 dB or more at 60 GHz, and in particular, sample No. 18 using the W conductor has a transmission signal of -2.5, while the comparative example is -5.9 at 60 GHz. You can see that

From the above results, Al ₂ was added to the dielectric material.
Even when W is used as the conductor material, O ₃ has a mounting structure in which the signal transmission line is not provided on the bottom surface of the wiring board and is electromagnetically coupled directly to the wiring layer on the external electric circuit board. It can be increased, and it can be understood that the transmission loss of the high frequency signal can be further reduced by using the low resistance metal for the conductor of the signal transmission line, as compared with the metallization using W.

At this time, S11 indicating the reflection of the signal is
In the case of the comparative example in which the transmission line is on the bottom surface of the wiring board, -10
Although it was more than dB, it was less than -10 dB in the present invention in which there is no transmission line on the bottom surface of the wiring board.

From this, it is understood that when the transmission line is on the bottom surface of the wiring board, the reflection with the wiring layer on the external electric circuit board increases and the transmitted signal decreases.

[0046]

As described in detail above, the mounting structure of the wiring board of the present invention has a signal transmission line provided on an insulating substrate on which a semiconductor element is housed or mounted, and an external electric circuit for surface mounting the wiring board. Electromagnetically coupled to form a pair of signal transmission lines that transmit high-frequency signals with the wiring layer of the board, which enables surface mounting with extremely low signal transmission loss, and high-frequency signal transmission. If the signal transmission line to be used is made of a conductor material having a small electric resistance such as Ag, Cu, Au, etc., the loss of high frequency signals can be further reduced, and at the same time, the dielectric material forming the insulating substrate or frame and the transmission line can be simultaneously formed. Baking is possible, mass productivity can be improved, and a wiring board can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a package for storing a semiconductor device in which the wiring board of the present invention is used.
FIG. 9 is a cross-sectional view showing a mounting structure applied to a semiconductor device, housing a high-frequency semiconductor element, and surface-mounting it on an external electric circuit board.

FIG. 2 is a diagram for explaining wiring in a void of the wiring board of FIG.

FIG. 3 is a mounting structure in which the wiring board of the present invention is applied to a semiconductor element housing package in which a semiconductor element mounted on an insulating base is sealed inside by a concave lid, and is surface-mounted on an external electric circuit board. FIG.

FIG. 4 is a cross-sectional view showing a mounting structure in which the wiring board of the present invention is applied to a multilayer wiring board in which a semiconductor element is directly connected to a wiring electrode on an insulating base and surface-mounted on an external electric circuit board.

FIG. 5 is a related art in which signal transmission lines are formed on a semiconductor element housing surface side and a bottom surface side of an insulating base, respectively, and a high-frequency signal input / output unit is electromagnetically coupled through a slot hole provided in a ground layer in the insulating base. FIG. 3 is a cross-sectional view showing a mounting structure in which the semiconductor element housing package described above is surface-mounted on an external electric circuit board.

[Explanation of symbols]

1 wiring board 2 Insulating substrate 3 Semiconductor element 4 First signal transmission line 5 slot holes 6 ground layer 7 External electric circuit board 8 Second signal transmission line 9 vacant places 10 frame 11 lid 12 Concave lid

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-6-21253 (JP, A) JP-A-6-85099 (JP, A) JP-A-8-172141 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01L 23/12

Claims (5)

(57) [Claims] 1. A first signal transmission line for electrically connecting the semiconductor element is formed on a surface of a wiring board for accommodating or mounting a semiconductor element having a dielectric material as an insulating substrate. A ground layer having a slot hole is formed in the insulating substrate, while a wiring layer formed on an external electric circuit board on which the wiring board is mounted is used as a second signal transmission line, and a ground formed on the wiring board. A connection portion is provided between the first signal transmission line and the second signal transmission line via a slot hole in a layer by an adhesive material such as solder.
A wiring board mounting structure, characterized in that the wiring board is mounted on a wiring layer of an external electric circuit board so as to be electromagnetically coupled without any need . 2. The wiring board is provided with a frame body which is formed integrally with an insulating base body to form a cavity for accommodating a semiconductor element therein, and the semiconductor element accommodated in the cavity is internally covered by a lid body. The mounting structure for a wiring board according to claim 1, which is a package for housing a semiconductor element which is sealed in a package. 3. The wiring board according to claim 1, wherein the wiring board is a package for accommodating a semiconductor element, in which a semiconductor element mounted on an insulating substrate is sealed with a concave lid. Mounting structure. 4. The signal transmission line comprises silver (Ag) and copper (C).
The wiring board mounting structure according to any one of claims 1 to 3, wherein the wiring board mounting structure is formed of at least one of u) and gold (Au). 5. The wiring board mounting structure according to claim 1, wherein a signal having a frequency of 10 GHz or more is transmitted through the signal transmission line.