JPH1012986A - Thick film printed circuit board - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To provide a thick-film printed circuit board capable of reducing the size and increasing the reliability of a semiconductor module while expanding the options of a semiconductor module structure. SOLUTION: At least one main surface forms an electronic component mounting surface, and the other main surface side has a carrier plate or a mother substrate 10.
A thick-film printed board 8 to be soldered to a surface, wherein the thick-film wiring 8a on one main surface of the thick-film printed substrate 8 is formed of an Ag-Pt system, and the thick-film wiring 8b on the other main surface is Is a thick film printed board characterized by being formed of an Ag-Pd system. That is,
According to the present invention, the conductive paste for forming the thick-film wirings 8a and 8b is appropriately used in accordance with the function and purpose, and the thick-film wiring 8a on one main surface requiring good bondability is formed of an Ag-Pt system. In addition, thick film wiring 8b on the other main surface side where solder resistance is required
The main point is that each was formed in the Ag-Pd system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thick-film printed board, and more particularly, to a thick-film printed board suitable for a more reliable semiconductor module.

[0002]

2. Description of the Related Art Semiconductor modules are widely used in various electronic devices because they can reduce the size and capacity of electronic circuits (or electric circuits).
A semiconductor module of this type has a configuration in which main parts are shown in cross section in FIG. For example, a thick film wiring (printed wiring pattern) 2a including a conductive pad (for example, a wire bonding pad) serving as a connection portion of the electronic component 1 to be mounted, such as a semiconductor element 1a and a capacitor 1b, is provided on one main surface. A thick-film printed board 2 having a configuration in which the main surface is soldered 4 to a carrier plate 3 or a mother board is used. A thick-film printed board 2 of this type includes a multilayer wiring board type or a thick-film wiring (printed wiring pattern) 2b including a conductor pad to be connected to the electronic component 1 on the other main surface side.
In such a configuration, for example, a configuration in which the thick film wirings 2a and 2b on both main surfaces are electrically and mechanically connected via a through hole 2c is also known.

[0005] In FIG. 3, reference numeral 5 denotes a thick film printed circuit board 2.
An adhesive layer for fixing the electronic component 1 mounted and arranged on one main surface of the thick-film printed board 2 to the surface of the thick-film printed board 2; Is a sealing cap for joining the open end to the edge of the carrier plate 3 to seal the thick print substrate 2 and the like.

Incidentally, the above-mentioned thick-film printed board is usually manufactured as follows. For example, a conductive paste made of Ag-Pt, Ag-Pd or Cu as a conductor is screen-printed on one main surface of a ceramic insulating substrate, and then fired at a temperature of about 600 to 900 ° C to form a conductive pad. Is formed. Next, on the other main surface of the ceramic-based insulating substrate, a conductive paste using Ag-Pt-based, Ag-Pd-based or Cu as a conductor is screen-printed, and then fired at a temperature of about 600 to 900 ° C. The thick film wiring 2b including the conductor pad is formed to obtain a double-sided thick film printed board.

Note that both thick film wirings 2 are formed through the through holes 2c.
When connecting a and 2b, a part of both thick film wirings 2a and 2b is overlapped on one of the surfaces. The thick film wirings 2a and 2b including the through hole 2c connection part are generally formed of one and the same material of Ag-Pt system, Ag-Pd system or Cu.

[0006]

However, in the structure of the above-mentioned thick film printed circuit board, the semiconductor material constituting the thick film wirings 2a and 2b has a problem such as pattern erosion due to solder and difficulty in wire bonding. Problems have been raised in terms of module miniaturization and reliability. That is, (1) When the thick film wirings 2a and 2b are formed of an Ag-Pt system, when soldered to a carrier plate or a mother board,
A part of the Ag-Pt system may be melted in the solder, which may cause an electrical open, which may impair the functional reliability.

(2) When the thick film wirings 2a and 2b are formed of an Ag-Pd system, the bondability of the Ag-Pd system is inferior, so that wire bonding is difficult, and the mounted semiconductor element 1a and the thick film printed board 2 There is a tendency that the reliability of electrical connection between the main surface and the connected portion is easily impaired. In particular, the Ag-Pd system is inferior in bondability to the Au wire often used for wire bonding, and the difficulty of the wire bonding is a serious problem in the configuration of the semiconductor module.

(3) Even when the thick film wirings 2a and 2b are formed of Cu, similar to the case of forming the Ag-Pd system, wire bonding is difficult and a highly reliable electrical connection is formed. There is a problem that it is difficult. Further, in the case of a Cu-based conductive paste, since it is necessary to prevent oxidation of Cu, selection and setting of the firing conditions are complicated, and there is a demerit that the cost is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a thick-film printed circuit board capable of reducing the size and increasing the reliability of a semiconductor module while expanding the options of a semiconductor module structure. I do.

[0010]

According to a first aspect of the present invention, there is provided a thick-film printed board in which at least one main surface forms an electronic component mounting surface and the other main surface is soldered to a carrier plate or a mother substrate surface. The thick-film wiring on one main surface of the thick-film printed board is formed of an Ag-Pt system, and the thick-film wiring on the other main surface is Ag.
-A thick-film printed board formed of a Pd-based material.

According to a second aspect of the present invention, there is provided a thick film printed circuit board having at least one principal surface forming an electronic component mounting surface and the other principal surface being soldered to a carrier plate or a mother substrate surface. The thick film wiring on one main surface is formed of an Ag-Pt system, and the thick film wiring on the other
It is a thick-film printed board formed of an Ag-Pd system.

According to a third aspect of the present invention, there is provided the thick film printed circuit board according to the first or second aspect, wherein the Ag-Pt thick film wiring on one principal surface side and the Ag-Pd thick film wiring on the other principal surface side. Is characterized by using an Ag-Pt-based thick film wiring as a lower layer when connecting in a multilayer manner.

That is, according to the present invention, the conductive paste for forming the thick film wiring is appropriately used in accordance with the function and purpose, and the thick film wiring on one main surface requiring good bondability is made of an Ag-Pt type. The main feature is that the thick-film wiring on the other main surface side, which is required to have solder resistance, is formed of an Ag-Pd system.

In the present invention, the thick-film printed board has a thick-film wiring on at least one principal surface thereof, which forms a mounting surface for electronic components,
If necessary, a double-sided or multilayer thick-film printed circuit board having a thick-film wiring for mounting electronic components on the other main surface side and configured to be solderable to a mother board surface or the like.
The thick-film printed board is generally of a ceramic type using, for example, alumina, aluminum nitride, or the like as an insulator. As described above, the thick-film wiring provided on one main surface is formed of Ag-Pt.
Although it is necessary that the thick film wiring provided on the other main surface side be composed of an Ag-Pd system, the material of the multi-layer type inner layer thick film wiring is the Ag-Pt system, the Ag-Pd system. Alternatively, another conductive system may be used, and there is no particular limitation. The components of the Ag-Pt paste are generally about 96 to 99% by weight of Ag, and Pt 1 to 4%.
% By weight, and the components of the Ag-Pd paste are
It is preferable to select about 85 to 90% by weight of Ag and about 15 to 10% by weight of Pd.

The thick film printed circuit board according to the present invention is manufactured by a conventional method for manufacturing a thick film printed circuit board except for selection and proper use of a material (conductive paste) for forming the thick film wiring. Can be. For example, after a hole for through-hole connection is formed at a predetermined position of a ceramic insulating plate, a paste containing a mixed powder of Ag-Pt having an average particle diameter of about 10 to 15 μm as a conductor is applied to one main surface. Screen printing and baking at a temperature of about 600 to 900 ° C. are performed to form thick-film wiring including connected parts of electronic components. Then, the average particle size is 10
A paste containing a mixed powder of Ag-Pd of about 15 μm as a conductor is screen-printed on the other main surface side and in the drilled holes, and fired at a temperature of about 600 to 900 ° C. to form a thick film including through-hole connection. By forming the wiring, a double-sided thick-film printed board is obtained.

The connection between the thick-film wiring layers may be screen-printed in the perforated holes when forming the thick-film wiring including the connected parts of the electronic component. In general, through holes are formed, but a configuration may be adopted in which a groove is provided along the side end surface of the insulating substrate, and the groove surface is formed into a conductor layer to connect the two surfaces. Further, the production of the thick film printed board can be performed by a so-called green sheet method.

According to the first and second aspects of the present invention, the thick film wiring on the electronic component mounting surface is formed of an Ag-Pt system, and the thick film wiring of the other main surface to be soldered is formed of an Ag-Pd system. ing. In other words, when the electronic component to be mounted and the thick film wiring are wire-bonded, the pads to be connected are formed of an Ag-Pt system having good bonding ability, so that wire bonding can be easily performed. it can. In addition, thick film wiring formed on the other main surface is made of Ag, which is hardly soluble in solder.
Since it is a Pd-based material, the risk of occurrence of open due to solder erosion or the like is eliminated, and as a result, a highly reliable semiconductor module can be provided while reducing the size.

According to the third aspect of the present invention, in the case where a connection structure in which the Ag-Pt thick film wiring and the Ag-Pd thick film wiring are connected in a multilayer manner is adopted, the Ag-Pd thick film wiring is connected to the Ag-Pt thick film wiring. By adopting a configuration that overlaps and covers the end of the thick-film wiring, the end of the Ag-Pt-based thick-film wiring that is easily dissolved in the solder is protected, thus further avoiding and reducing the adverse effects of solder. It is planned.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS.

FIG. 1 is a cross-sectional view showing the structure of a main part of the first embodiment. Reference numeral 8 denotes a surface on which one main surface forms a mounting surface of an electronic component 9 and the other main surface forms a surface for soldering on a carrier plate 10. It is a thick film printed board to be attached. Here, the thick film printed board 8 is made of, for example, an insulating alumina-based ceramic plate 8 ′ having a thickness of about 0.5 mm and sides of about 8 × 8 mm as an insulator, and a Ag surface on one main surface side.
A thick film wiring 8a including a -Pt-based connected portion (for example, a bonding pad) is formed, and Ag-Pd is formed on the other main surface side.
A system thick film wiring 8b is formed. Further, these thick film wirings 8a and 8b are formed so as to extend on the inner wall surface of the through hole 8c formed at a required position of the alumina ceramic plate 8 '.
They are electrically connected by an Ag-Pt-based conductor layer 8d.

Next, an example of a method of manufacturing the thick film printed board 8 will be described.

First, an insulating alumina-based ceramic plate 8 'having a required size or standard is prepared, and a through hole 8c is formed at a predetermined position. On the other hand, Ag- with an average particle size of about 10 to 15 μm
Ag using Pt mixed powder (weight ratio Ag: Pt = 99: 1) as conductor
-Pt-based conductive paste, Ag with an average particle size of about 10 to 15 μm-
Ag with Pd mixed powder (weight ratio Ag: Pd = 85: 15) as conductor
-Prepare a Pd-based conductive paste.

Next, on one main surface of the insulating alumina-based ceramic plate 8 ', a wiring including a pad for wire-bonding to an electrode terminal of an electronic component 9 to be mounted by screen printing of an Ag-Pt-based conductive paste. Print the pattern and the inner wall surface of the through hole 8c. Thereafter, the printed insulating alumina-based ceramic plate 8 'is housed in an electric furnace, and baked in an air atmosphere at a temperature of 600 to 900 [deg.] C. to form an Ag-Pt thick film wiring 8a and a through-hole conductor layer. 8d
To form

Next, an Ag-Pd-based conductive paste is screen-printed on the other main surface of the insulating alumina-based ceramic plate 8 'to form a wiring partially overlapping the edge of the through-hole conductor layer 8d. Provide a pattern. Thereafter, the printed insulating alumina-based ceramic plate 8 'is housed in an electric furnace, and the printed wiring pattern is baked at a temperature of 600 to 900 ° C. in an air atmosphere to obtain an Ag-Pd-based wiring pattern. Thick film wiring
By forming 8b, a film-thickness printed board having a main part configuration as shown in FIG. 1 can be obtained with a high yield.

FIG. 2 is a cross-sectional view showing the structure of a main part of the second embodiment. Reference numeral 8 denotes a main surface forming an electronic component 9 mounting surface, and another main surface soldering to a carrier plate 10 surface. It is a thick film printed board to be attached. Here, the thick film printed board 8 is made of, for example, an insulating alumina-based ceramic plate 8 ′ having a thickness of about 0.5 mm and sides of about 8 × 8 mm as an insulator, and a Ag surface on one main surface side.
A thick film wiring 8a including a -Pt-based connected portion (for example, a bonding pad) is formed, and Ag-Pd is formed on the other main surface side.
A system thick film wiring 8b is formed. Further, these thick film wirings 8a and 8b are formed so as to extend on the inner wall surface of the through hole 8c formed at a required position of the alumina ceramic plate 8 '.
They are electrically connected by an Ag-Pd-based conductor layer 8d '.

Next, an example of a method of manufacturing the thick film printed board 8 will be described.

First, an insulating alumina-based ceramic plate 8 'having a required size or standard is prepared, and a through hole 8c is formed at a predetermined position. On the other hand, Ag- with an average particle size of about 10 to 15 μm
Ag using Pt mixed powder (weight ratio Ag: Pt = 99: 1) as conductor
-Pt-based conductive paste, Ag with an average particle size of about 10 to 15 μm-
Ag with Pd mixed powder (weight ratio Ag: Pd = 85: 15) as conductor
-Prepare a Pd-based conductive paste.

Next, on one main surface of the insulating alumina-based ceramic plate 8 ', a wiring including a pad for wire-bonding with an electrode terminal of an electronic component 9 to be mounted is screen-printed with an Ag-Pt-based conductive paste. Print the pattern. Thereafter, the printed insulating alumina-based ceramic plate 8 'is placed in an electric furnace, and is placed in an air atmosphere at 600 to 900 ° C.
The baking process is performed at a temperature of 5 mm to form an Ag-Pt thick film wiring 8a.

Next, an Ag-Pd-based conductive paste is screen-printed on the other main surface of the insulating alumina-based ceramic plate 8 'including the inner wall surfaces of the through holes 8c to form the Ag-Pt-based thick film wiring 8a. A wiring pattern including a through-hole conductor partially overlapping is provided at the edge. Thereafter, the printed insulating alumina-based ceramic plate 8 'is housed in an electric furnace, and the printed wiring pattern is baked at a temperature of 600 to 900 ° C. in an air atmosphere to obtain an Ag-Pd-based wiring pattern. By forming the thick film wiring 8b including the through-hole conductor layer 8d ',
As shown in FIG. 2, a printed circuit board having a main part configuration as shown in FIG. The thick film printed circuit board having the above-described structure is used for a semiconductor module, and the semiconductor module is formed by a conventional mounting means employing a wire bonding method. Connection was formed. After the other main surface of the semiconductor module formed above was incorporated into a carrier plate or a mother substrate surface by conventional soldering means, and electrical characteristics were evaluated. There was no occurrence of dissolution, occurrence of electrical opening, etc., and a highly reliable circuit configuration was maintained. It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the thick-film printed board may be a multilayer type other than the double-sided type, and the insulator may be a ceramic type other than alumina, such as aluminum nitride. Further, in consideration of downsizing of the configuration or improvement of the wiring density, the electrical connection between the wiring pattern layers is preferably through hole connection or via connection, but is not limited thereto.

[0030]

According to the present invention, since a thick film wiring including a pad to which an electronic component is wire-bonded is formed of an Ag-Pt system having good bonding ability, a highly reliable wire bonding can be performed. Easy to achieve. On the other hand, since the thick-film wiring on the other main surface is formed of an Ag-Pd system that is hardly soluble in solder, the possibility of occurrence of open due to solder erosion or the like is eliminated. As described above, the fact that wire bonding can be easily performed means that it is not necessary to mount and mount the semiconductor element as a mold package, and the semiconductor module can be made compact. Also, taking into account solder resistance, the skillful use of the insolubility of the Ag-Pd-based film prevents problems due to soldering, etc. A highly reliable semiconductor module can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a main part of a thick-film printed board according to a first embodiment.

FIG. 2 is a cross-sectional view illustrating a configuration of a main part of a thick-film printed board according to a second embodiment.

FIG. 3 is a cross-sectional view showing a main part configuration of a conventional semiconductor module.

[Explanation of symbols]

 1, 9: electronic components 1a: semiconductor element 1b: capacitor 2, 8: thick film printed circuit board 2a, 8a: thick wiring on one main surface 2b, 8b: thick film on the other main surface Wiring 2c, 8c Through hole 3, 10 Carrier plate 4 Solder layer 5 Adhesive layer 6 Bonding wire 7 Sealing cap 8d, 8d 'Through hole conductor layer

Claims (3)

[Claims] At least one principal surface forms an electronic component mounting surface, and the other principal surface side is a thick film printed board which is soldered to a carrier plate or a mother substrate surface, wherein the one principal surface side of the thick film printed substrate is Wherein the thick film wiring is formed of an Ag-Pt system and the thick film wiring of the other main surface is formed of an Ag-Pd system. 2. A thick-film printed board having at least one main surface forming an electronic component mounting surface and the other main surface being soldered to a carrier plate or a mother board surface, wherein the one main surface side of the thick-film printed substrate Is formed of an Ag-Pt system, and the thick-film wiring on the other main surface to be through-hole connected is Ag-Pt.
A thick-film printed board formed of a Pd-based material. 3. When the Ag-Pt thick film wiring on one main surface side and the Ag-Pd thick film wiring on the other main surface side are connected in a multilayer manner,
3. The thick-film printed circuit board according to claim 1, wherein the Pt-based thick-film wiring is a lower layer.