JP2000299543A - Inter-substrate connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a relatively simple configuration with high connection strength when a printed wiring board is connected flush with a ceramic substrate. SOLUTION: A connection part 3 is provided on the rear surface side of a ceramic substrate 2 while a printed wiring board 1 is provided with a through hole 7. The printed wiring board 1 is also provided with a through hole 4 where a THD part 5 is mounted. With the upper surface of a seat 8 comprising an open part 8a applied with an adhesive 10, the printed wiring board 1 and the ceramic substrate 2 are, in aligned state, mechanically bonded and fixed. A connection conductor 9 comprising a clip part 9a, pin-like part 9b, and bent part is so arranged as to connect the printed wiring board 1 to the ceramic substrate 2, and fed to a solder flow process. Related to the connection conductor 9, the ceramic substrate 2 is electrically connected to the printed wiring board 1 by solder connection parts 11 and 12. At the same time, the THD part 5 is also soldered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inter-board connection structure for connecting a printed wiring board and a ceramic substrate so as to be substantially flush with each other.

[0002]

In recent years, for example, electronic devices used in automobiles and the like are often used in a form in which a printed board and a ceramic board are connected. As a first conventional technique in such a connection structure between substrates, there is one disclosed in JP-A-6-181386. In this method, a solder paste is applied to a land formed on a bottom surface of a glass substrate, a through hole corresponding to the land is formed on a printed wiring board, and the glass substrate is overlapped with the printed wiring board in an aligned state. The connection is made by heating the solder paste.

As a second prior art, Japanese Patent Laid-Open No.
JP-A-121870 discloses that a glass substrate disposed on an upper surface of a substrate supporting piece of a housing and a printed wiring board disposed on a lower surface of the substrate supporting piece are provided with folded portions at both upper and lower ends and are subjected to solder plating. A configuration is shown in which the connection is made by the clip terminals and the soldering is performed by heating from the lateral direction. Further, as a third prior art, Japanese Patent Laid-Open Publication No.
Japanese Patent Application Laid-Open No. 9745 discloses a configuration in which two substrates are overlapped so that their edges are aligned, and a flexible wiring board is put on the peripheral edges so as to be turned upside down and then pressed and held by clips.

[0004] However, in each of the above-mentioned prior arts, the two substrates are connected so as to be stacked one on top of the other, and when the printed wiring board and the ceramic substrate are connected so as to be substantially flush with each other. Was not applicable. In each of the above prior arts, both the mechanical fixing and the electrical connection between the substrates are performed by the solder connection portion or the clip, so that the connection strength is poor and the connection reliability is low. . In the first prior art, a large stress acts on the solder connection due to the difference in the coefficient of thermal expansion between the glass substrate and the printed wiring board. In the second prior art, the soldering process is complicated. There was also a disadvantage that it was troublesome.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to connect a printed wiring board and a ceramic substrate so as to be substantially flush with each other. An object of the present invention is to provide a board-to-board connection structure which has excellent strength and can improve connection reliability.

[0006]

According to the inter-substrate connection structure of the present invention, connection portions for electrical connection are provided on the back surface of the printed wiring board and the back surface of the ceramic substrate, respectively. On a pedestal having a shape that has an open portion that straddles and exposes at least both connection portions,
The printed wiring board and the ceramic substrate are mechanically fixed, and both ends of a connection conductor for electrically connecting the printed wiring board and the ceramic substrate are soldered to both connection portions. It has features (the invention of claim 1).

According to this, the printed wiring board and the ceramic substrate are mechanically fixed on the pedestal so as to be substantially flush with each other, and at the same time, are electrically connected by the connection conductor. As a result, the connected printed wiring board and ceramic substrate can be handled as a single substrate. At this time, since the connection portions for electrical connection provided on the back surface of the printed wiring board and the back surface of the ceramic substrate are arranged on the same plane, the solder between each connection portion and both ends of the connection conductor is connected. Attachment can be performed simultaneously. Further, since the pedestal is provided with an open portion and both connection portions are exposed, it is needless to say that the workability of soldering is not impaired.

Therefore, according to the first aspect of the present invention, the printed wiring board and the ceramic substrate are connected so as to be substantially flush with each other, and have a relatively simple configuration, excellent connection strength, and excellent connection reliability. And an excellent effect that the soldering process can be easily completed.

In this case, the pedestal can also serve as a heat radiation member (the invention of claim 2). According to this, the connection with the heat radiating member generally required especially in the ceramic substrate can be achieved by fixing to the pedestal without using a separate heat radiating member and a connecting step, and as a result, the number of parts is increased. Without inviting, the process can be completed more easily.

A bent portion may be provided at an unfixed portion of the intermediate portion of the connection conductor (the invention of claim 3), or the connection conductor may be made of a flexible material. (Invention of claim 4). According to these, the stress generated due to the difference in the coefficient of thermal expansion between the printed wiring board and the ceramic substrate is absorbed by bending or stretching at the unfixed bent portion of the connection conductor or expansion and contraction of the flexible connection conductor. , The stress can be effectively prevented from acting on the solder connection part.

Further, in the case where a lead insertion type component is mounted on the printed wiring board, the connection conductor is soldered simultaneously with the soldering of the lead insertion type component. According to this, the soldering process of the connection conductor and the lead insertion type component can be performed by one flow process, and the soldering process can be further improved. It can be done easily.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention (corresponding to claims 1, 2, 3, and 5) will be described below with reference to FIGS. FIG. 1 shows details of a connection structure in which a printed wiring board 1 and a ceramic substrate 2 are connected to be on the same surface in the present embodiment. The ceramic substrate 2 has a substantially rectangular plate shape as shown in FIG. 2, and although not shown, for example, a semiconductor chip component or the like is mounted on the surface thereof to constitute a hybrid IC or the like. . As shown in FIGS. 1 and 3, a connection portion 3 for electrical connection with the printed wiring board 1, which is made of, for example, a copper-plated electrode, is formed at a right end portion on the back side of the ceramic substrate 2. ing.

On the other hand, the printed wiring board 1 has a substantially rectangular plate shape as shown in FIG. 2, and a predetermined circuit is formed by mounting various electronic components on the surface. At this time, as shown in FIGS. 1 and 3, the printed wiring board 1 is provided with through holes 4 for mounting components, and a lead insertion type component (THD component) 5 The device is mounted by being inserted into the through hole 4 and soldered on the back surface side (the solder connection portion 6 is shown in FIG. 1). Further, a through hole 7 is provided at a left end portion of the printed wiring board 1 as a connection portion for electrical connection with the ceramic substrate 2.

Here, the pedestal 8 and the connection conductor 9 are used for connecting the printed wiring board 1 and the ceramic substrate 2. As shown in FIG. 2, the pedestal 8 has a shape extending over both the ceramic substrate 2 and the printed wiring board 1 and having an opening 8a for exposing at least the connection portion 3 and the through hole 7, and in this case, the upper surface is substantially It has a U-shaped plate shape.

In this embodiment, the pedestal 8 is made of a material having good heat conductivity, for example, aluminum, and also serves as a heat radiating member of the ceramic substrate 2. As described below, the ceramic substrate 2 and the printed wiring board 1 are mechanically bonded and fixed to each other on the upper surface of the pedestal 8 by an adhesive 10 in a state where they are arranged side by side at predetermined intervals. Has become.

The connection conductor 9 is made of a thin metal plate having good wettability with a solder such as copper.
As shown in FIG. 3 and FIG.
Has a clip portion 9a positioned so as to sandwich the right end (the portion where the connection portion 3 is formed) from above and below, and has a pin-like shape inserted into the through hole 7 of the printed wiring board 1 from above at the right end. A portion 9b is integrally provided. further,
The intermediate portion of the connection conductor 9 is bent in a stepped shape, and thus has a bent portion 9c.

As will be described later, the back surface of the clip portion 9a of the connection conductor 9 is soldered to the connection portion 3 (a solder connection portion 11 is shown in FIG. 1).
The lower end of b is soldered to a land on the back side of the through hole 7 (a solder connection portion 12 is shown in FIG. 1), whereby the ceramic substrate 2 and the printed wiring board 1 are connected. They are electrically connected.

Now, the procedure for connecting the printed wiring board 1 and the ceramic substrate 2 will be described. First, FIG.
As shown in (2), a step of applying an adhesive 10 on the upper surface of the pedestal 8 and bonding and fixing the printed wiring board 1 and the ceramic substrate 2 in a state of alignment is performed. Due to the curing of the adhesive 10, the printed wiring board 1 and the ceramic substrate 2
It is mechanically fixed on the pedestal 8 at predetermined intervals so as to be on the same plane. At this time, the back surface of the connection portion 3 of the ceramic substrate 2 and the back surface of the through hole 7 of the printed wiring board 1 are located at the open portion 8a of the pedestal 8 and are exposed. Also, the through holes 4 of the printed wiring board 1
Are also exposed on the back side.

Next, as shown in FIG. 3, a step of arranging the connection conductor 9 so as to connect the printed wiring board 1 and the ceramic substrate 2 is performed. At this time, the clip portion 9a of the connection conductor 9 is arranged so as to sandwich the portion where the connection portion 3 of the ceramic substrate 2 is formed, and the pin-like portion 9b is inserted into the through hole 7 of the printed wiring board 1. In this case, the connection conductor 9 is temporarily held between the printed wiring board 1 and the ceramic substrate 2 without bonding or the like. At the same time, the THD component 5 is arranged on the printed wiring board 1 with the lead portion 5a inserted into the through hole 4.

Then, from this state, a soldering step is performed. In this soldering step, the printed wiring board 1 and the ceramic substrate 2 connected via the pedestal 8 are handled as a so-called single substrate, and are performed by well-known flow soldering on the back surface thereof. Thus, as shown in FIG. 1, the clip portion 9a of the connection conductor 9 is connected to the connection portion 3 by the solder connection portion 11, and the pin-like portion 9b is connected to the through hole 7 by the solder connection portion 12. Thus, the ceramic substrate 2 and the printed wiring board 1 are electrically connected by the connection conductor 9. At the same time, in the printed wiring board 1, the THD component 5 is connected to the through hole 4 by the solder connection portion 6.

In this case, since the back surface of the printed wiring board 1 and the back surface of the ceramic substrate 2 are arranged on the same plane, the connection conductor 9 is soldered to the through hole 7 and the connection portion 3 in the same process. Further, the soldering of the THD component 5 on the printed wiring board 1 can be performed at the same time. Further, since the pedestal 8 is provided with the opening 8a, it goes without saying that the workability of soldering is not impaired.

In such a connection structure between the printed wiring board 1 and the ceramic substrate 2, both the mechanical fixing and the electrical connection between the substrates are performed by the conventional solder connection portion or clip. Unlike this, the base 8 mechanically secures the substrates 1 and 2 and the connection conductors 9 make electrical connection, so that the connection strength is excellent and the connection reliability can be improved. However, due to repeated thermal cycles, stress may be generated due to a difference in the coefficient of thermal expansion between the printed wiring board 1 and the ceramic substrate 2. However, the bent portion 9 c is provided in the middle of the connection conductor 9. Because
The stress is absorbed by bending and stretching at the bent portion 9c,
It is possible to alleviate the stress and effectively prevent a large stress from acting on the solder connection portions 11 and 12.

Therefore, according to the present embodiment, the printed wiring board 1 and the ceramic substrate 2 are connected so as to be substantially flush with each other, and have a relatively simple structure, excellent connection strength, and excellent connection reliability. And furthermore, an excellent effect that the soldering process can be easily completed can be obtained. In this embodiment,
Since the pedestal 8 is also used as a heat radiating member, the structure and the connecting process can be simplified without increasing the number of parts.

FIG. 4 shows another embodiment (corresponding to claim 4) of the present invention. The difference from the above embodiment is as follows. That is, in this embodiment, the connection conductor 21
Is a flexible material, in this case one side (top side in the figure)
And a copper tape coated with an adhesive. Along with this, a connection portion 23 made of, for example, a copper-plated electrode is provided on the left end on the back side of the printed wiring board 22.
Are formed.

In this case, the lower side of the connection conductor 21 is soldered to the connection portion 3 of the ceramic substrate 2 by a solder connection portion 24, and the lower side of the right end portion is soldered to the connection portion 23 by a solder connection portion 25. It is supposed to be. Thus, the ceramic substrate 2 and the printed wiring board 22 are electrically connected. At this time, the connecting conductor 21 made of copper tape has a longer dimension, and an intermediate portion thereof is folded upward to provide a bent portion 21a. Solder is prevented from being attached to the bent portion 21a,
The connection conductor 21 can be expanded and contracted by the bent portion 21a.

Also in this configuration, similarly to the above-described embodiment, first, a step of bonding and fixing the printed wiring board 22 and the ceramic substrate 2 to the upper surface of the pedestal 8 in an aligned state is executed. A step of arranging and temporarily holding between the printed wiring board 22 and the ceramic substrate 2 is executed. This temporary holding is performed by the adhesive on the upper surface of the connection conductor 21. Thereafter, the left and right end portions of the connection conductor 21 are connected to the connection portion 3 and the connection portion 23 by the solder connection portions 24 and 25, respectively, in a solder flow process.

According to such an embodiment, the printed wiring board 22 and the ceramic
Are connected so that they are almost on the same plane. With a relatively simple configuration, the connection strength can be improved and the connection reliability can be improved. Furthermore, the soldering process can be simplified. An excellent effect that can be achieved can be obtained. The printed wiring board 22 and the ceramic substrate 2
The stress generated due to the difference in the coefficient of thermal expansion can be absorbed and reduced by the expansion and contraction of the flexible connection conductor 21, and effectively preventing the stress from acting on the solder connection portions 24 and 25. You can do it.

In the above embodiment, if the solder adheres to the entire lower surface of the connection conductor 21 made of copper tape, the flexibility (stretchability) of the connection conductor 21 may be impaired. It is necessary to prevent the solder from being attached to the intermediate portion of the connection conductor 21. Therefore, as shown in FIG. 5, a pedestal 27 integrally having a mask portion 26 for covering the lower surface side of the intermediate portion of the connection conductor 21 so that the solder does not adhere thereto.
May be used. In this case, the upper surface of the mask portion 26 is configured to be slightly lower than the upper surface of the pedestal 27, and the pedestal 27 is provided with open portions 27a and 27b to expose the connection portions 3 and 23. ing.

In addition, the present invention is not limited to the above-described embodiments. For example, a case accommodating both substrates may be used as a pedestal, and the pedestal necessarily serves also as a heat radiating member. It doesn't have to be something. Further, the flexible connection member may be a carrier tape on which a conductor portion is formed, or the like, and the present invention may be appropriately modified and implemented without departing from the gist.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is an enlarged longitudinal sectional view of a main part showing a connection structure between a printed wiring board and a ceramic substrate.

FIG. 2 is a perspective view showing a pedestal, a printed wiring board, and a ceramic substrate.

FIG. 3 is an enlarged longitudinal sectional view of a main part showing a state before soldering.

FIG. 4 is a view corresponding to FIG. 1, showing another embodiment of the present invention.

FIG. 5 is a plan view showing another example of the base.

[Explanation of symbols]

In the drawings, reference numerals 1 and 22 are printed wiring boards, 2 is a ceramic substrate, 3 and 23 are connection portions, 4 is a through hole, 5 is a lead insertion type component, 7 is a through hole (connection portion), 8, 27 are pedestals, 8a, 27a and 27b are open portions, 9 and 21 are connection conductors, 9c and 21a are bent portions, 10 is an adhesive, 11, 1
Reference numerals 2, 24, and 25 indicate solder connection portions, and reference numeral 26 indicates a mask portion.

Claims (5)

[Claims] 1. A structure for connecting a printed wiring board and a ceramic substrate so as to be substantially flush with each other, wherein the printed wiring board and the ceramic substrate are electrically connected to a back surface of the printed wiring board and a back surface of the ceramic substrate, respectively. A connecting portion is provided, and the printed wiring board and the ceramic substrate are mechanically fixed on a pedestal having a shape that has an open portion that straddles both the printed wiring board and the ceramic substrate and exposes at least the both connecting portions. A board-to-board connection structure, wherein both ends of a connection conductor for electrically connecting the printed wiring board and the ceramic substrate are soldered to the two connection parts, respectively. 2. The board-to-board connection structure according to claim 1, wherein said pedestal also serves as a heat radiating member. 3. The board-to-board connection structure according to claim 1, wherein a bent portion is provided in an unfixed portion of the intermediate portion of the connection conductor. 4. The inter-board connection structure according to claim 1, wherein the connection conductor is made of a flexible material. 5. A lead insertion type component is mounted on the printed wiring board, and soldering of the lead insertion type component is performed simultaneously with soldering of the connection conductor. The connection structure between substrates according to any one of claims 1 to 4.