JPH0156556B2 - - Google Patents

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to an integrated circuit device, particularly an integrated circuit device having a structure in which a main substrate on which a film integrated circuit is formed and a sub-substrate on which a film integrated circuit is formed are mounted. Related to improvements in circuit devices.

(b) Background of the Technology A hybrid integrated circuit is defined as a combination of two or more dissimilar integrated circuits, or a circuit consisting of one or more independent devices or components and one or more integrated circuits. There are combinations of film integrated circuits and individual parts, film integrated circuits and semiconductor integrated circuits, film integrated circuits and semiconductor integrated circuits and individual parts, and semiconductor integrated circuits and individual parts.

In this way, many hybrid integrated circuits use film integrated circuits, and compared to semiconductor integrated circuits, hybrid integrated circuits are characterized by a greater degree of freedom in design, a wider range of resistance and capacitance values, and a wider range of resistance and capacitance values. It can be selected precisely, it is easy to separate elements and circuits and reduce parasitic capacitance, it is advantageous for high power or low power, it can be supplied quickly and it is profitable even in small quantities, etc. The advantages of this are largely due to membrane integrated circuits.

As is well known, there are two types of film integrated circuits: thin film integrated circuits and thick film integrated circuits. Integrated circuits are economical and compact, and are selected depending on system requirements.

(c) Prior art and problems Active filters are a typical example where hybrid integrated circuits are applied.

Active filters use thin film integrated circuits because the resistors and capacitors used in the circuit are required to have narrow tolerances and stability in constants. An operational amplifier circuit is mounted to form a filter circuit, and external connection terminals are also connected to this board.

In this structure, as shown in FIG.
On the top, in addition to the circuit element forming area 2 (shown with diagonal lines in the figure) of resistors and capacitors, which are the original purpose of the thin film integrated circuit, there are also operational amplifiers 3 and external connection terminals 4.
It is necessary to provide a wide area 5 for forming circuits that do not necessarily need to be thin films, such as connecting parts (only a portion of which is shown), and in some cases, more than half of the board area is covered by these areas. This is used for circuit parts such as connection areas that do not need to be formed by thin films.

In addition, most of the thin-film resistors and capacitors mentioned above that require high precision and high stability in active filters are elements that determine the time constant and constitute a closed loop circuit, and the allowable range of the time constant is usually About ±1 [%], in strict cases ±0.1
[%] is required.

However, it is unavoidable that the capacitance value of the capacitor element varies by several percent during the manufacturing process, and it is often necessary to correct the time constant after forming the thin film integrated circuit.

A practical method for making this correction is to first measure the capacitance value of the capacitor and then trim the resistor so that the time constant, ie, the product of the capacitance value and the resistance value, becomes a predetermined value. However, in order to accurately measure capacitance and resistance values, it is necessary to cut and separate one part of the closed loop circuit to create an open loop when forming the circuit pattern. This cut and separate circuit is closed by bonding, soldering, etc., or it is made into a closed loop externally via an external connection terminal.

In this way, forming a closed loop after adjusting the resistance value requires a considerable increase in man-hours and substrate area.

As explained above, the conventional active filter integrated circuit device composed of a single thin film integrated circuit is difficult to miniaturize and increase the scale of integration, and is expensive, and there is a strong demand for improvement. There is.

A structure in which a hybrid film integrated circuit is formed by dividing it into a plurality of substrates, that is, one main substrate and one or more sub-substrates mounted thereon, is already known.
This structure makes it easy to supply similar devices, such as integrated circuit devices with the same basic circuit but different input/output conditions and pin layouts.
It has effects such as being effective in reducing the size and increasing the scale of integration. The structure according to the present invention, in which only the circuit parts that require high precision are formed as thin film integrated circuits on a sub-substrate and mounted on the main substrate on which thick film integrated circuits are formed, has the advantages of thin film and thick film. It is an effective means of making the most of

Therefore, a structure in which a hybrid film integrated circuit is divided into a main substrate and a sub-substrate is one of the most effective means for meeting the above requirements and further developing hybrid film integrated circuits.

However, it is by no means easy to connect a sub-substrate on which a film integrated circuit, especially a thin film integrated circuit, is formed to a main substrate on which a thick film integrated circuit is formed with sufficient reliability. This connection is further complicated by the fact that it is formed on both sides, and that semiconductor integrated circuits and individual components are generally mounted on the membrane integrated circuit.

The following method is conventionally known as a method for arranging two substrates on which film integrated circuits are formed in parallel and connecting both circuits to each other at desired positions.

One method is to provide connection pads at corresponding positions around the periphery of a plurality of substrates, which are usually of the same size, and to connect these pads with lead wires. In this method, flexibility in pattern arrangement is lost and a considerable number of man-hours are required in the connection process.

It does not require that the substrate sizes be the same,
A solder bump method is a method with a large degree of freedom in pattern arrangement. In this method, corresponding connection pads are provided at arbitrary positions on both substrates, and the connection is made between them by melting solder balls. Although this method has great utility value,
There is still room for improvement, including the fact that it is not easy to provide the space necessary for flux removal between opposing surfaces of the substrate with good reproducibility.

Regarding hybrid integrated circuit devices that use multiple substrates, we will further improve their functionality and integration scale, reduce their size,
In order to promote improvement in economic efficiency, there are other points to be improved in addition to the above, and a further improved structure is required.

(d) Purpose of the Invention The present invention relates to a membrane integrated circuit device constituting an active filter circuit, and advances a structure in which the circuit is divided and formed on a plurality of substrates, thereby improving its function, integration scale, miniaturization, and economical efficiency. The aim is to further promote the improvement of

(e) Structure of the Invention The object of the present invention is to provide an integrated circuit device that constitutes an active filter circuit comprising at least a plurality of film-formed resistor and capacitor circuit elements and an operational amplifier. A first substrate having a pattern and a second substrate having a thin film-formed circuit pattern are provided;
The first substrate is manufactured by forming the circuit pattern by separating the circuit elements so as not to form a closed loop with each other, and trimming the circuit elements for adjusting element values, and the first substrate The circuit pattern having connection pads for connecting circuit elements in a closed loop is formed, and an external connection terminal is connected to one side of the first substrate, and the first substrate and the second substrate are connected to each other. The circuit board is connected to the circuit board by soldering the connection pads of both boards through metal balls, and by mounting the operational amplifier in a region other than the area where the second board is mounted on the first board. This is achieved by an integrated circuit device characterized in that the element is formed into a closed loop by the circuit pattern of the first substrate to form the active filter circuit.

(f) Embodiments of the Invention The features of the present invention will be explained below by exemplifying the manufacturing method for realizing the integrated circuit device of the present invention, and then a more specific embodiment of an active filter will be shown.

(i) Method for manufacturing thick film integrated circuits For example, a 96% Al ₂ O ₃ ceramic substrate is used as the substrate, and the required thick film integrated circuit is formed with AgPd-based conductors, RuO ₂ -based resistors, etc., and soldered. Cover areas where adhesion is not allowed and the resistor with a glass protective film.

When forming thick film integrated circuits on both the front and back surfaces of a substrate, the above method is applied to each surface. If it is necessary to electrically connect circuits on both sides at a required position, use a board with a hole penetrating the front and back sides at that position in advance, and use suction from the opposite side of the board during conductor printing. By this, the paste is allowed to flow into the hole and adhere to the end face of the hole, and the through hole is formed by firing.

Note that it is desirable that the resistors be concentrated on only one side. This is because the first side must be fired before the paste is printed on the second side, so the resistor on the first side is fired twice and the glass component in the resistor paste progresses to separate, forming a resistor. This is because the value decreases, and the amount of decrease changes depending on the sheet resistance value and resistance pattern, and the variation width is also large.

(ii) Manufacturing method for thin film integrated circuits Examples of substrates for forming thin film integrated circuits include
Use 99.5% Al ₂ O ₃ alumina substrate or glazed substrate. It is generally advantageous for thin film integrated circuits to be formed on only one side of a substrate.

On the substrate, the resistor is made of e.g. Ta ₂ N or
TaAlN, etc., the capacitor is e.g. Ta ₂ O ₅
A thin film integrated circuit is formed by using the dielectric material as a dielectric material and the conductor as an Au film formed on a Ta film via NiCr, for example. Next, grooves for dividing the substrate are formed using, for example, a CO ₂ laser.

Thereafter, the thin film integrated circuit is coated with an organic insulating film, such as a resist film. however,
This film is not formed on the connection pad and its vicinity and the area where laser trimming is performed for element value adjustment. This film has the effect of protecting the element and preventing solder adhesion. If element value adjustment is required, it is carried out in this state using, for example, a YAG laser.

As mentioned above, the organic insulating film has the effect of preventing solder from adhering to the thin film integrated circuit, but there is a weakness in this blocking effect.

That is, as shown in FIG. 2a, on the substrate 11
A conductive pattern consisting of a Ta film 12, a NiCr film 13, and an Au film 14 is formed, which is selectively covered with an organic insulating film 15, and solder 1 is placed on the conductive pattern not covered with the organic insulating film 15.
6, the solder 16 invades the interface between the organic insulating film 15 and the Au film 14. For example, the solder penetration speed may reach 0.3 [mm/sec] for molten solder at a temperature of 230 [° C.].

In order to prevent this molten solder from entering, in the present invention, as shown in FIG.
7 is provided, and the organic insulating film 15 is terminated within this groove 17. In this groove 17, electrical connection is made only through the Ta film 12, and the conductor resistance increases, but an arrangement is possible that does not adversely affect the characteristics of the integrated circuit.

(iii) How to prepare the sub-board for connection If a thin-film integrated circuit is formed on the sub-board, paste is printed on the connection pads of this thin-film integrated circuit for soldering, and then solder is applied. Place a metal ball and perform solder reflow to form bumps.

In this example, the metal ball is made of silver (Ag).
is used. This is because Ag has the best electrical conductivity and thermal conductivity, and has the flexibility to absorb external stress.

By using metal balls to form the bumps, it becomes possible to easily control the distance between the two substrates when the sub-substrate, which will be described later, is connected to the main substrate. In order to completely clean the flux by flowing liquid bubbling after soldering which connects both boards, it is necessary that this interval is 0.3 [mm] or more, and in this example, the diameter of the sphere is 0.28 [mm] or more. mm], achieving the necessary and sufficient spacing.

The method for placing the soldered metal ball on the connection pad is to
Place a stainless steel plate with a 0.5 mm hole in close contact with the sub-board, drop a metal ball into the hole,
Heating is performed in this state.

If a thick film integrated circuit is formed on the sub-board, solder paste is printed at the connection position with the main board, and bumps using metal balls are formed thereon in the same manner as described above.

(iv) How to connect the sub-board to the main board A thick film circuit is usually formed on the main board, but
At the connection position of this thick film integrated circuit with the sub-board and the connection position of the semiconductor integrated circuit or individual components,
Print the solder paste. The thickness of the solder film is, for example, about 0.2 [mm].

The prepared sub-board and other parts are mounted opposite to this connection position, and solder fusion is performed in a reflow oven. This solder reflow method has the effect that when the solder is fused, the position of the mounted component is corrected by itself toward the center of the connection pad due to its surface tension.

When connecting sub-boards or components to both the front and back surfaces of the main board, solder paste printing and reflow processing are performed on the second side after the connection on the first side is completed. During this reflow process on the second surface, the sub-board and components connected to the first surface are located on the bottom surface of the main board, and the solder that connects them is also melted.
As shown in the distribution example when the size is 0.5 [mm] x 0.5 [mm], the surface tension of the molten solder is large, and by selecting the area and number of connection pads, the sub-board and components located on the bottom surface can be The second side can be soldered while holding it without dropping it.

(v) Connection of external connection terminals, etc. The main board that has been soldered and mounted as described above is divided into modules using, for example, a CO ₂ laser.

A solder film is formed at the connection position of the external connection terminal when forming the solder film for mounting the sub-board etc., and the external connection terminal is soldered using a local heating method such as hot air blowing. Let's do it. Next, the required exterior is applied.

(vi) Allocation of circuits between main and sub-boards Figure 4 shows an example of an active filter circuit, 21 is an operational amplifier, C ₁ to C ₄ and R ₁ to
_R6 is a thin film capacitor element and a resistor element that require high precision and high stability.

In manufacturing this active filter as a hybrid integrated circuit device according to the present invention, circuit elements such as resistors and capacitors formed as thin films within the range indicated by the dashed line in FIG. are separated from each other and formed in an open loop state on a sub-substrate, and other circuit parts are formed on the main substrate using thick film circuits. If the circuits are shared between the main and sub boards as described above and the circuit connections between the main and sub boards are made using the manufacturing method described above, circuit elements such as resistors and capacitors will be open on the sub board. Because it is in a loop state, the resistance value can be adjusted with high precision in the trimming process, and the process of connecting the main and sub boards simultaneously creates a closed loop of the active filter circuit.・Highly reliable integrated circuit devices for active filter circuits can be mass-produced and can be provided at low cost.

Furthermore, a resistive element connected in parallel to the resistive element _R5 , as shown by the broken line in FIG. 4, for example.
The resistance element R' ₆ connected in parallel to R' ₅ and the resistance element R ₆ is formed as a thick film resistance element on the main substrate, and has a resistance value of, for example, about 10 times or more than that of the thin film resistance elements R ₅ and R ₆ . If provided, after soldering the sub-board and operational amplifier 21,
It is possible to easily adjust the gain by trimming the thick film resistive elements _R'5 and _R'6 .

The thick film resistive elements _R'5 and _R'6 are thin film resistive elements.
May be inserted in series with R ₅ and R ₆ , R ₅ and R′ ₅
And, by selecting the distribution of resistance values between R ₆ and R′ ₆ , the characteristics are not affected.

(vii) An example in which a thick film circuit is formed on only one side of the main substrate. FIG. 5b is a cross-sectional view showing the X-Y cross section.

The main substrate 31 is printed with an AgPd-based thick film conductor, and a glass layer to prevent solder adhesion is printed thereon. Integrated circuits made of Ta-based thin films are formed on the sub-substrates 32 and 33, and as described above, 3
4, it is soldered and connected to the thick film circuit of the main board 31 via the Ag bulb. Also, the operational amplifier 35
Dual in-line made of plastic
It is a package type. Note that 36 is a thick film circuit forming area, and 37 is an external connection terminal.

In this embodiment, by adjusting the resistance value of the resistance element on the sub-board as described above, the cut-off frequency can be adjusted without adjusting the resistance value in the operating state of the active filter.
It is kept within 0.5 [%].

In this embodiment, the size of the device is reduced to about 7/8 compared to the conventional device, but the manufacturing cost is reduced to about 2/3.

(viii) Embodiment in which thick film integrated circuits are formed on two sides of the main substrate Figures 6a and b are plan views showing a 6th-order low-pass active filter in which thick film integrated circuits are formed on two sides of the main board. It is.

The main substrate 41 has thick film integrated circuits selectively connected by through holes formed on two sides, and the substrate 42 has an operational amplifier 45 formed on one side and a thin film integrated circuit formed on the other side, which will be explained first. It is installed using a manufacturing method that However, 46 and 4
6' is a thick film integrated circuit forming area, and 47 is an external connection terminal.

In this example, it is approximately 1/1 compared to the conventional example.
2, and the manufacturing cost has been reduced by about 3/4.

(g) Effects of the Invention As explained above, according to the present invention, the closed loop circuit formed by the integrated circuit of the integrated circuit device is intentionally formed as an open loop circuit on the sub-board, and this open-loop circuit is formed on the main board. By means of an integrated circuit device, the closed loop is completed by a soldered connection through a metal ball, which forms the circuit part that closes the loop circuit and is highly reliable and easy to work with. The effects of substrate division, such as downsizing, increasing the scale of integration, or effectively using thin-film integrated circuits and thick-film integrated circuits, can be easily achieved with high reliability and economy.

In addition, if necessary, the resistance value can be easily adjusted by realizing some of the resistance elements by connecting each resistance element formed on the sub-board and the main board in parallel or in series. As a result, the above effect is further magnified.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a conventional example of an active filter hybrid thin film integrated circuit, FIG. 2 a is a sectional view showing a conventional example near the connection pad of the thin film integrated circuit, and FIG. 3 is a diagram showing the effect of the surface tension of molten solder on the connection pad, FIG. 4 is a circuit diagram showing an example of an active filter, and FIG. 5a is a plan view of one embodiment of the present invention. Figure 5b is a sectional view, Figures 6a and b
FIG. 3 is a plan view showing two planes of another embodiment. In the figure, 11 is a substrate, 12 is a Ta film, and 13 is a Ta film.
is NiCr film, 14 is Au film, 15 is insulating film, 1
6 is solder, 17 is a groove, 21 is an operational amplifier, 31
and 41 are main boards, 32, 33 and 42 are sub boards, 34 are soldered connections via Ag balls, 35
and 45 are operational amplifiers, 36, 46 and 46' are thick film integrated circuit forming regions, and 37 and 47 are external connection terminals.

Claims (1)

[Claims] 1. In an integrated circuit device constituting an active filter circuit comprising at least a plurality of film-formed resistor and capacitor circuit elements and an operational amplifier, a first circuit pattern having a thick film-formed circuit pattern is provided. A second substrate having a circuit pattern formed as a thin film on the substrate is provided, and the second substrate has the circuit pattern formed by separating the circuit elements so as not to form a closed loop with each other, and the circuit elements of the circuit element. The first substrate is manufactured by being trimmed for adjusting element values, and the first substrate is formed with the circuit pattern having connection pads for connecting the circuit elements in a closed loop, and the circuit pattern is formed on one side of the first substrate. is connected to an external connection terminal, and the first board and the second board are connected to each other by soldering the connection pads of both through a metal ball,
Furthermore, by mounting the operational amplifier in a region other than the area where the second board is mounted on the first board, the circuit elements are made into a closed loop by the circuit pattern of the first board and the active circuit elements are closed. An integrated circuit device comprising a filter circuit.