JPH0239597A - Forming method for thick film circuit - Google Patents

Abstract

PURPOSE:To form a thick film circuit with high yield by forming a connecting conductor having a thickness substantially corresponding to the step of the edge of a viahole region or an insulator connected to a lower conductor by a direct lithography, and forming an upper conductor for connecting a plurality of connecting conductors by a direct lithography. CONSTITUTION:Lower conductors 83 are formed on a board 42, dried and baked. Then, insulators 82 are formed in a predetermined pattern, dried, and baked. In this case, viaholes 84 for connecting the independent conductor 83 is simultaneously formed. The thickness of the insulator 82 is considerably thicker than that of the conductor 83, and a large step is generated at the edges of the viahole 84 and the insulator 82. Then, a connecting conductor 11 of thickness substantially corresponding to the depth of the viahole 84 is formed at the part of the viahole 84. A connecting conductor 11' is also formed at a position for connecting the conductor 83 at a part having large step of the edge of the insulator 82. After the conductors 11, 11' are formed, they are dried and connected. Then, an upper conductor 81 is so formed by lithography as to connect the conductors 11, 11' formed in the viaholes 84, 84.

Description

[Detailed Description of the Invention] [Field of Use after Graduation] The present invention relates to a method for forming a thick film circuit, and particularly to a method for forming a thick film circuit that is formed by direct writing to form a thick film circuit consisting of a laminated layer of conductors and insulators. It is something.

[Prior art] J! The No. 11 simulated circuit formation technique is used in the manufacture of hybrid ICs. A hybrid IC is formed by forming a thick film circuit on a substrate and mounting discrete circuit elements through through holes by soldering or the like.

Such an IC requires a relatively high current carrying capacity i1) and P!
jll! It is used in applications where circuit configuration is difficult using forming technology.

Like thin-film ICs, current high-density ICs are required to be highly dense and multi-layered, and for this reason, they have a structure in which multiple conductor patterns are laminated in many layers with insulators in between. Via holes are required to connect conductor patterns that cannot be connected within the same pattern plane.

A via hole is a hole provided in an insulator that is exposed to connect an isolated conductor pattern provided below the insulator. The insulator is made of glass paste etc.
Sufficient insulation can be maintained with a typical film thickness of 40 to 507 zm. However, the film thickness of this insulator is
The film thickness of a conductor made of silver or the like is 10 to 20 gm, which is considerably thicker, and therefore, when an insulator is applied, a considerably large step is created at its edge and at the via hole portion.

FIGS. 8(A) to (C) show an example of a thick film circuit in a hybrid IC, FIG. 8(A) is a plan view of the thick film circuit,
(B) and (C) are cross sections taken along lines xx and Y-Y in FIG. It is a conductor and has a circuit pattern as shown by the broken line in FIG. 8(A). Further, reference numeral -82 denotes an insulator made of glass or the like, and has a shape as shown by the -dotted chain line in FIG. 8(A). The insulator 82 has a via hole portion 84 for connecting the isolated lower conductor 83. Reference numeral 8 designates a 1-2 part conductor, which has a pattern shown in solid lines in FIG.

[Problem to be solved by Origin 1] In the structure shown in V, the required film thickness of the insulator 82 is much larger than the film thickness of the lower conductor, as shown in FIGS. 8(B) and (C). This results in a fairly large step difference at the edge of the via hole 84 or the insulator 82 .

Screen printing or direct drawing can be considered as a method for forming the circuit 1 model, but in particular, when direct drawing is performed, the portions of the via holes 84 or insulation as shown in FIGS. Wire breakage is likely to occur at the step at the edge of the body 82.

This situation is shown in FIGS. 9(A) and 9(B). In FIG. 9, reference numeral 43 indicates a nozzle for discharging conductive paste to a predetermined thickness for forming the upper conductor 81. Figure 9 (A)
As shown in the figure, when forming the upper conductor 81 on the stepped portion of the insulator 82, the substrate is moved at a constant speed in the X (or Y) direction in the figure, and during that time a constant amount of paste 91 is applied from the nozzle 43 per unit time. is discharged.

Usually, a configuration is used in which a height sensor or the like is provided to make the position of the nozzle 43 follow the unevenness of the insulator 82, etc.; In B), the paste is pulled as shown by reference numeral 92, and the wire breaks without following the step of the board.

In particular, as shown in Fig. 10, when each conductor is connected through multiple insulators due to pattern design, a very large step as shown by numeral 87 occurs. Now, the completely continuous upper conductor 81
It was difficult to form it reliably.

It is an object of the present invention to solve these problems and to make it possible to manufacture circuits with a thickness of 11 mm with a completely continuous conductor pattern at a high yield.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, a method for forming a thick film circuit consisting of a laminated layer of conductors and insulators is formed by direct writing. (7) a step of forming a lower conductor; a step of forming an insulator on the lower conductor; and a step of forming the lower conductor in a via hole area provided in the insulator or at the edge of the insulator for connecting the lower conductor and the upper conductor. A step of forming a connecting conductor connected to the lower conductor in the connecting area of some of the conductors and having a thickness that is approximately compatible with the step of the via hole area or the edge of the insulator by direct drawing, and an upper part connecting the plurality of connecting conductors. When forming a thick film circuit from the process of forming a conductor by direct drawing, or when forming an insulator consisting of multiple layers especially on the lower conductor,
The area of the insulator on the upper layer side is made smaller than the area of the insulator on the double layer side, and then an upper conductor is formed that crosses the edges of the multiple layers of insulators and connects to the lower conductor of the lower layer. .

[Function] According to the above configuration, when forming an upper conductor that crosses over an insulator to connect a lower conductor, it is possible to form a connecting conductor and then connect the connecting conductors to each other without causing disconnection. Can be coupled with a conductor. In addition, when forming multiple layers of insulators, by making the area of the insulator on the F layer side smaller than that on the lower layer side, it is possible to reduce the level difference at the edge of the insulator and prevent disconnection of the upper conductor. It can be prevented.

[Example] The present invention will be described in detail below based on an example shown in one drawing.

Figure 4 shows the direct drawing device used in the present invention.

Further, FIG. 5 shows the structure of the control system of the apparatus shown in FIG. 4.

In FIG. 4, reference numeral 42 denotes a circuit board made of ceramic or the like, and an XY table 45 that is moved in the X and Y directions.
is positioned at a predetermined position above.

A nozzle 43 for discharging paste that forms a conductor and an insulator onto the substrate 42 is placed directly in front of the XY child table 5, and is moved via a drive mechanism 44 in the Z-axis direction perpendicular to the XY plane. Ru.

Paste discharge from nozzle 43 and discharge stop, XY
By numerically controlling the movement of the child table 5 in the XY plane according to a predetermined program,
Various circuit films can be formed on the substrate 42. At this time, the unevenness of the substrate 42 is detected by the height sensor 41, and the height of the nozzle 43 is detected by the drive mechanism 44 along the Z-axis direction.
automatically controlled via.

In FIG. 5, reference numeral 55 denotes a motor driver for controlling a motor for moving the XY child table 5 in the XY force directions, and is controlled by a CPU 51 comprising a microprocessor or the like via a motor controller 54. Further, the height of the nozzle 43 is made up of a motor driver 44a and a motor controller 44b that constitute the drive mechanism 44 shown in FIG. The height of the nozzle 43 is also controlled by the CPU 51.

Further, the height of the nozzle 43 from the substrate 42 at the film forming position is detected by the height sensor 41, and this detection information is input to the CPU 51. The nozzle 43 is configured to discharge the material at a constant speed by the pressure of an air source 56 consisting of a compressor or the like, and the discharge and discharge stop are controlled by pressure control. It is controlled by a magnetic valve 58.

The opening/closing of the solenoid valve 58 is controlled by the CPU 5 via the controller 57.
1. CPU51 is ROM or R
According to the program stored in advance in the memory 52 consisting of an AM or the like, the movement of the XY child table 5 in the XY plane is controlled via the motor driver 55 as described above, and the material is moved at an appropriate timing via the solenoid valve 58. Ejection/non-ejection is controlled to form a pattern on the substrate 42.

At this time, the height of the nozzle 43 from the substrate 42 is constantly detected by the height sensor 41, and the height of the nozzle 43 is adjusted via the motor driver 44a according to this detected value. Such direct drawing operations are controlled via an input/output device 53 comprised of a keyboard, a display board, and the like.

Figure 3 shows the flow of the entire direct drawing process performed using the apparatus shown in Figures 4 and 5.
), and FIGS. 1(A) to 2(D) show the states of the conductor film or insulating film formed sequentially by the procedure shown in FIG. 3. ) to (D) respectively show the state of film formation when forming the same circuit pattern as shown in FIGS. 8(B) and (C). below,
The procedure for forming a thick film circuit in this embodiment will be explained with reference to FIGS. 1 to 3.

In step Sl of FIG. 3, the lower conductor 83 is
, are formed on the substrate 42 as shown in FIG. 2(A). At this time, the CPU 51 controls the movement of the XY child table 5 and the discharge/non-discharge of the paste according to the pattern of the insulator 82 stored in the memory 52 in advance in the same manner as in the conventional method. The lower conductor 83 thus obtained is dried and fired.

Subsequently, in step S3, FIG. 1(B) and FIG. 2(B)
As shown in FIG. 2, an insulator 82 is formed in a predetermined pattern. At this time, a via hole 84 for connecting the isolated lower conductor 83 is formed at the same time. The thickness of the insulator 82 made of glass paste or the like (for example, 40~
50pm) is the lower conductor 83 (for example, lO~20ILm) made of gold, silver, palladium alloy, etc. as in the conventional case.
It is considerably thicker than the via hole 84 and the insulator 82.
There is a large step at the edge. In step S4, the insulator 82 is dried and fired.

Subsequently, in step S5, the connection conductor 11 is formed in the via hole 84 as shown in FIG. 1(C). In the past, the upper conductor was formed directly from via hole part to via hole part, but in this embodiment, as shown in the figure, the upper conductor is formed with a thickness approximately equivalent to the depth of the via hole 84 (for example, 20 to 30 g).
The connection conductor 11 of m) is provided only in the via hole 84. Further, the connecting conductor 11' is formed not only in the via hole 84 but also at a position where the connection with the lower conductor 83 is to be made in a large stepped portion of the edge of the insulator 82, as shown in FIG. 2(C). After forming these connecting conductors 11° and 11', these conductors are dried and fired in step S6.

In step S7, the upper conductor 81 is
Draw with a thickness of 20JLm. In this case, as shown in FIG. 1(D), the L oil conductor 81 is drawn so as to connect the connection conductor 11.11 already formed in the via hole 84.84. At this time, since the connecting conductor 11 has already been formed, the step that the upper conductor 81 must overcome is much smaller than in the past, and the lower conductor 83 must be reliably connected via the connecting conductor 11 without causing any disconnection. can be connected. As shown in FIG. 2CD), the same applies to the edge of the insulator 82, and since the level difference that the L oil conductor 81 overcomes is small at this position as well, the lower conductor can be reliably connected.

This situation is shown in Fig. 6 (A) and (B). Fig. 6 (A)
, (B) correspond to FIGS. 9(A) and (B), and the insulator 82
The case where the upper conductor 81 is formed with paste 91 at the edge of is shown.

According to the procedure described in ■-, the connection conductor 11'' has been formed in advance at the edge of the insulator 82 (or the via hole part) as shown in FIG. 6(A).
), the step portion becomes smaller and the upper conductor 81 can be reliably formed without disconnection. In this case, it goes without saying that by adjusting the height of the nozzle 43 via the height sensor 41, a reliable conductor pattern can be formed.

When the drawing of the upper conductor is completed in step S7, the upper conductor is dried and fired in step S8, and the process ends. Furthermore, in the case of forming multiple insulating layers and conductive layers, the above procedure may be repeated.

According to the above embodiment, conductors are formed in advance in areas where insulator steps tend to be large, such as via holes or insulator edges, and after drying and firing, an E oil conductor is formed to connect them. As a result, thick film circuits can be formed with high yield without causing disconnection of conductors.

In the embodiment 1-, the upper conductor crosses a single insulating layer to connect the lower conductor, but as shown in FIG.
2, it is preferable to configure the area of the insulator on the 1- side of the plurality of insulators 82 to be smaller than the area of the lower insulator, as shown in FIG. Since the actual angle of the stepped portion becomes gentler, the upper conductor can be reliably formed without causing wire breakage.

[Effects of the Invention] As is clear from the above, according to the present invention, in a thick film circuit forming method for forming a thick film circuit made of a laminated layer of conductors and insulators by direct writing, a lower conductor is formed on a substrate. a step of forming an insulator on the F oil conductor; and a step of connecting the lower conductor and the lower conductor in the via hole area provided in the insulator or the edge of the insulator for connecting the lower conductor and the upper conductor. forming a connecting conductor connected to the lower conductor in the area by direct drawing and having a thickness approximately corresponding to the step of the via pole area or the edge of the insulator; and forming an upper conductor connecting the plurality of connecting conductors by direct drawing. When forming a thick film circuit from the stage of formation, or especially when forming an insulator consisting of multiple layers on the lower conductor, the area of the insulator on the F layer side should be larger than the area of the insulator on the lower layer side. Since the 1-oil conductor is formed small and then crosses over the edges of multiple layers of insulators to connect to the lower conductor of the lower layer, the upper conductor that crosses over the insulators and connects the lower conductor. In the case where the connecting conductors are formed, once the connecting conductors are formed, the connecting conductors can be connected to each other by the upper conductor without causing disconnection or the like. In addition, when forming multiple layers of insulators, by making the area of the insulator on the upper layer smaller than that on the lower layer, the step at the edge of the insulator can be reduced, preventing disconnection of the upper conductor. This method has an excellent effect in that a thick film circuit having a completely continuous conductor pattern can be manufactured with high yield.

[Brief explanation of the drawing]

11, 4(A)-(D) and FIG. 2(A>-(D)
zl? and zl? respectively show how the thick film circuit is formed according to the present invention.
FIG. 3 is a flowchart showing the f order of thick film circuit formation according to the present invention. FIG. 4 is a perspective view showing the configuration of the direct writing apparatus used in the present invention. A block diagram showing the configuration of the control system in Figure 6 (A
), (B) is an explanatory diagram showing the advantages of the present invention, No. 7
The figures are cross-sectional views showing different methods of forming an insulator according to the present invention, FIG. 8(A) is a top view of a thick film circuit pattern, and FIG. 8(B) is a top view of a thick film circuit pattern.
, (C) are cross-sectional views taken along lines x-X and Y-Y in FIG. 8(A), respectively, and FIGS. 9(A) and CB) show problems with the conventional thick film circuit forming method. The explanatory diagram, FIG. 10, is a sectional view showing different problems caused by the conventional method. 11... Connection conductor 41... Height sensor 42.
・・・ノ、(Plate 43... Nozzle 44...
Drive a mechanism 45...XY table 51...CP
U 52...Memory 54...Motor controller 55...Motor driver 58...' City valve 82...Insulator 84...Via hole 81...Upper conductor 83...Lower conductor 91 ...Paste Station's 1st shift) r Tomari Totoihanaki - Commentary Review Figure 6

Claims (1)

[Claims] 1) A method for forming a thick film circuit in which a thick film circuit consisting of a laminated layer of a conductor and an insulator is formed by direct writing, which includes the step of forming a lower conductor on a substrate, and forming an insulator on the lower conductor. forming a via hole region provided in the insulator for connecting the lower conductor and the upper conductor, or a connecting region of the lower conductor and the upper conductor at the edge of the insulator, the via hole region or the insulator connected to the lower conductor; A process of forming a connecting conductor with a thickness approximately equivalent to the step at the body edge by direct drawing;
A method for forming a thick film circuit, comprising the step of forming an upper conductor connecting the plurality of connection conductors by direct drawing. 2) A method for forming a thick film circuit in which a thick film circuit consisting of a stack of conductors and insulators is formed by direct writing, which includes a step of forming a lower conductor on a substrate and forming an insulator consisting of multiple layers on the lower conductor. In this case, the area of the insulator on the upper layer side is formed smaller than the area of the insulator on the lower layer side, and the upper conductor is formed to be connected to the lower conductor of the lower layer beyond the edges of the multiple layers of insulators. A method for forming a thick film circuit, comprising the steps of: