JPH02297993A - Manufacture of film circuit device - Google Patents

Abstract

PURPOSE:To securely and easily detect A crack formed after dividing a substrate by comparing the resistance of a crack detecting film resistor after dividing a substrate circuit. CONSTITUTION:An assembly substrate 3 containing 12 unit alumina porceralain substrates 2 divided by division lines 1 is prepared. There are provided on one insulating principal surface 4 of the unit circuit substrate 2 a thick film conductor 5, a thick film resistor 8, and a mini-molded transistor 7 bonded to the thick film conductor 8 and protected by silicon rubber, and further terminals a-n. Further, a crack detecting thick film resistor 8 is illustratively provided with hatched lines between terminals a and b. The crack detecting thick film 8 containing parts 8a, 8b, 8c, and 8d located along outer peripheral edges in four directions of the principal surface 4 of the unit circuit substrate 2 and disposed substantially into an annular shape. The assembly substrate 2 with such construction is cut by the division lines 1, and resistance of the crack detecting film resistor 8 is measured to detect any crack formed after the division.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a membrane circuit device that allows easy detection of cracks in a unit circuit board obtained by dividing the circuit board.

[Prior Art and Problems to be Solved by the Invention] Ceramic substrates, insulated metal substrates, crawler substrates, and the like are used as circuit boards for hybrid ICs. These substrates are subjected to various thermal and mechanical stresses until the hybrid IC is completed. The main processes that apply stress include the process of printing conductors and resistors, the process of mounting components, the process of dividing a large board for multiple ICs into individual boards, and the process of attaching to soil using resin molding and the like. Therefore, in extreme cases, cracks may occur in the substrate, leading to variations in the characteristics of the film circuit. Although it was rare, there were times when a part of the circuit would go into an oven state.

In recent years, there has been a trend to make substrates thinner in order to make them smaller and lighter, and to shorten heat dissipation buses, making them more likely to crack. Although the occurrence of such cracks can be reduced by considering the structural design of the substrate, it cannot be completely eliminated. Moreover, cracks are so small that they cannot be identified at first glance, and it is difficult to completely detect them even by visual inspection using a microscope. In extreme cases that lead to open circuits, the presence of cracks can be detected by checking the electrical characteristics of the circuit, but if the cracks are minute or the location where they occur is in a place where no membrane circuit is formed. In some cases, it is difficult to detect the presence of cracks from electrical characteristics. Therefore, even if no abnormality is found in these tests, as the hybrid IC is used for a long period of time, cracks will gradually grow due to heat stress applied by turning the electricity on and off, and the characteristics of the hybrid IC will change. Sometimes it appeared. Therefore, there was a possibility that a product with a reliability risk might be shipped.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing a membrane circuit device that allows rack detection to be performed easily and reliably as described above.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a circuit board in which a film circuit and a film resistor for crack detection are respectively formed in a plurality of regions divided by regions to be divided. a step of dividing the circuit board in the planned dividing area to obtain a plurality of unit circuit boards; and measuring the resistance value of the crack detection film resistor included in the unit circuit board to detect the occurrence of cracks. The present invention relates to a method for manufacturing a membrane circuit device, characterized by comprising a step of determining a state.

[Operations and Effects of the Invention] According to the above invention, the resistance value of the crack detection film resistor formed on the unit circuit board changes based on the crack that occurs in the area where the crack detection film resistor is formed. . Therefore, by comparing the resistance values of the film resistors for crack detection after the board circuit is divided, cracks formed after the board is divided can be easily and reliably detected.
A highly reliable circuit device can be provided.

[Embodiment] FIGS. 1 to 3 show a method of manufacturing a device having a thick film circuit on a substrate, that is, a hybrid IC, according to an embodiment of the present invention. In this example, a collective board (circuit board) (3) including 12 unit alumina porcelain boards (2) divided by dividing lines (planned dividing lines or planned areas) (1) shown in FIG. 1 is used. A circuit shown in FIG. 3 is formed on each unit substrate (2).

One insulating main surface (4) of the unit circuit board (2) in Figure 3
A silver-palladium thick film conductor (5
), a ruthenium oxide thick film resistor (6), and a thick film conductor (
Mini mold transistor (7) face-down bonded to 5) and protected by silicone rubber coating.
and 14 electrode pads or terminals (a)
. . . -(n), according to the invention, a crack detection thick film resistor (8) is provided between the terminals a and b, which is illustrated with diagonal lines.

This crack detection thick film resistor (8) is a ruthenium oxide thick film resistor, and is located along the outer peripheral edge in four directions of the main surface (4) of the unit circuit board (2) (8a), (8b) ( 8c)
(8d) and are arranged in a substantially annular shape. That is, the first
As is clear from the figure, a thick film resistor (8) for crack detection is provided at least adjacent to the dividing line (1).

Cracks first occur at the edges of the unit circuit board (2),
It takes the process of growing inside the unit circuit board (2). Therefore, at least in the areas where cracks are likely to occur, the thick film resistor (8) for crack detection is inserted from the edge of the unit circuit board (2).
It is necessary to set the distance to 11 or less, more preferably 0.5 mm or less. Therefore, in this embodiment, the thick film resistor (8) for crack detection and the main surface (4) of the unit circuit board (2)
The distance from the edge of the unit circuit board (2) is about 0.4Il111 along the long side of the unit circuit board (2).

Thick film resistor (8) for crack detection is connected to film conductor (sheet resistor 1
Ω/□ or less), the film conductor contains a large amount of metal to improve conductivity compared to the film resistor, and the viscosity becomes higher than when the film conductor is formed of a film resistor. For this reason, cracks and breaks are difficult to occur due to cracks in the unit circuit board (2), and crack detection sensitivity is poor, making it impossible to put it to practical use. Therefore, it is desirable that the thick film resistor (8) for crack detection be formed of a thick film resistor with a sheet resistance value of at least 50 Ω/□, and in practical terms, it is preferable to form the thick film resistor (8) with a sheet resistance value of at least 50 Ω/□ to 50 Ω/□. desirable. Therefore, in this embodiment, the sheet resistance value of the thick film resistor (8) for crack detection is set to approximately 5Ω/□. Note that even if the sheet resistance of the thick film resistor (8) for crack detection is small, the crack detection sensitivity (resistance change rate) is the same. However, if the sheet resistance is small, the increase in the thick film resistor (8) for crack detection, that is, the absolute value, will be small, and a highly sensitive resistance measuring device (one with good full + constant sensitivity in a small range) will be required. Become. 1st
After each unit circuit board (2) shown in the figure is provided with the circuit shown in FIG. 3, it is cut along the dividing line (1) to form an independent unit circuit board (2). In this cutting process, unit circuit boards (2
), this crack will be detected in subsequent measurements.

Each terminal (a) to (n) of the divided unit circuit board (2)
A lead member (9) is connected to the lead member (9) as shown in FIG. 2, and the hybrid IC is completed by molding with epoxy resin (10).

In order to detect cracks that occur during various steps until the device shown in FIG. second end)
The resistance value between is set as 1111.

If a crack occurs near the edge of the unit circuit board (2) so as to reach the crack detection thick film resistor (8), the resistance value will be set to the set value (the crack detection thick film resistor before division).
The resistance value of 8) is several tens of percent higher than the resistance value of 8). Therefore,
Cracks can be detected easily and reliably.

Since the crack detection thick film resistor (8) is provided so as to surround the original circuit portion, it is most affected by cracks. Therefore, the thick film resistor (8) for detecting cracks can be used to detect not only racks whose circuit parts become defective but also racks which do not become defective. In the past, pass/fail was determined only by the characteristics of the circuit part, so products with racks that were not an immediate problem were used as non-defective products. However, there is a risk that cracks will grow in the future and the circuit device will become defective. According to this embodiment, since it is possible to detect cracks that do not reach the circuit portion, it is possible to provide a highly reliable circuit device.

Next, FIGS. 4 and 5 showing another embodiment of the present invention will be described. However, parts common to those in FIG. 3 are given the same reference numerals and their explanations will be omitted.

In the circuit device shown in FIG. 4, thick film resistors (8) for crack detection are provided along all edges of the unit circuit board (2). Even with this configuration, terminals (a) and (0
) Cracks can be detected by the resistance value between them.

In the circuit device shown in FIG. 5, the thick film resistor (8) for crack detection is not provided at the edge of the unit 7 circuit board (2) on the side where the terminals (a) to (0) are arranged. . but,
Since thick film resistors (8) for detecting cracks are provided in the remaining three directions, substantially the same effects as those of the devices shown in FIGS. 3 and 4 can be obtained.

[Modifications] The present invention is not limited to the above-described embodiments, and, for example, the following modifications are possible.

(A) The unit circuit board (2) of the example does not have through-holes or notches, but if it does have these, cracks are likely to occur in the vicinity, so cracks should also be detected in the vicinity. It is desirable to provide a thick film resistor (8).

Therefore, the edge of the insulating main surface in the present application includes not only the outer circumferential edge but also the inner circumferential edge, the edge of the notch, and the like.

(B) In order to save the area of the unit circuit board (2), the thick film resistor (8) for crack detection may not be provided in an annular shape, but may be formed only at the edge where cracks are likely to occur.

For example, in a rectangular substrate with a large aspect ratio, cracks are likely to occur along the long sides, and when a crack occurs on one long side, cracks are likely to occur on the other long side as well. The thick-film resistor (8) for crack detection may be provided only on one long side near the main part.

(C) The thick film resistor (8) for crack detection may also be used as a circuit element or for other purposes.

(D) It is also applicable when using a metal substrate with a film-like insulating layer provided on it instead of the ceramic substrate (2).

(E) Cracks may be detected before molding with resin (10).

[Brief explanation of drawings]

Fig. 1 is a plan view showing an assembly of circuit boards according to an embodiment of the present invention, Fig. 2 is a perspective view showing a part of a completed no-ibrid IC, and Fig. 3 is a state of the no-ibrid IC before molding. FIGS. 4 and 5 are plan views showing hybrid ICs according to other embodiments of the present invention, respectively. (1)...Parting line, (2)...Porcelain substrate, (3)...
... Collective board, (4) ... Insulating main surface, (5) ...
Thick film conductor, (6) Thick film resistor, (7) Transistor, (8) Thick film resistor for crack detection, (9)
... Lead member, (10) ... Epoxy resin.

Claims (5)

[Claims] (1) A step of preparing a circuit board in which a film circuit and a film resistor for crack detection are respectively formed in a plurality of regions partitioned by the planned division regions, and dividing the circuit board by the planned division regions to create a plurality of A film circuit device comprising the steps of: obtaining a unit circuit board; and determining a crack occurrence state by measuring the resistance value of the crack detection film resistor included in the unit circuit board. Production method. (2) The film resistor for crack detection is formed along the region to be divided, and the distance between the resistor for crack detection and the region to be divided is within 1 mm. A method for manufacturing the membrane circuit device described above. (3) The method for manufacturing a membrane circuit device according to claim 1 or 2, wherein the crack detection membrane resistor has a sheet resistance value of 50Ω/□ or more. (4) Claim 1, characterized in that the crack detection resistor is arranged so as to surround the membrane circuit.
A method for manufacturing a membrane circuit device according to item 1 or 2 or 3. (5) The unit circuit board is a planar rectangular board, and the crack detection film resistor is arranged along the longitudinal direction of the rectangle.
A method for manufacturing a membrane circuit device according to item 1 or 2 or 3 or 4.