JP2002016335A - Metal foil-clad laminated board containing internal layer circuit, printed wiring board, and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an metal foil clad laminated board containing an internal layer circuit that can inspect the impedance value of the internal layer circuit during the manufacture of a printed wiring board, can reduce the manufacturing costs of the printed wiring board, and at the same time can shorten the manufacturing period of the printed wiring board. SOLUTION: In this metal foil clad laminated sheet containing the internal layer circuit, metal foil 21 is laminated at one side or both sides of a core part 2 having an internal layer circuit 1 via an insulating layer 20. In this case, a test pattern 3 for impedance measurement is formed in the same layer as the internal layer circuit 1, and at the same time at least one end of the test pattern 3 is exposed on an end face 16 at the core 2. A probe 31 of an impedance measuring instrument is brought closer from the side for bringing the probe 31 into contact with the test pattern 3 easily.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal foil-clad laminate having an inner layer circuit used for processing into a high-frequency multilayer printed wiring board, a printed wiring board using the same, and a method of manufacturing the same. .

[0002]

2. Description of the Related Art A circuit board used for an electronic device or the like is designed to match impedance between a circuit (circuit pattern) provided on the circuit board and a signal transmitted through the circuit. In the case of a signal circuit (signal pattern) for transmitting the signal (high-speed signal), impedance matching is important. Therefore, the signal circuit of the circuit board is designed so that impedance matching can be achieved with the signal transmitted therethrough, and the signal circuit of the circuit board determines whether the impedance value is within a certain allowable range from the design value. Has been inspected and commercialized. Then, a circuit board whose impedance value of the signal circuit is out of a predetermined allowable range from a design value is discarded as a defective product.

When a printed wiring board such as a multilayer printed wiring board is used as a circuit board as described above, signal circuits requiring impedance matching exist in an inner layer and an outer layer, and the inner circuit (inner pattern) and the outer circuit are used. (Outer layer pattern) is subjected to the same inspection as described above. However, as a method for inspecting whether or not the impedance value of the inner layer circuit of the printed wiring board is within a certain allowable range from the design value, There are a method of directly measuring the impedance value of the signal circuit of the inner layer circuit, and a method of providing a test pattern different from the signal circuit of the inner layer circuit and measuring the impedance value. The test pattern may be provided in a portion of the printed wiring board that is to be a product and has no inner layer circuit, or may be provided in a portion of the printed wiring board that is not to be a product (a so-called discard substrate portion). The impedance value is also designed to be a predetermined constant value. Then, the impedance value of the test pattern is measured, and for a printed wiring board in which the impedance value of the test pattern deviates from the design value by a certain tolerance, the impedance value of the signal circuit of the inner layer circuit also deviates from the design value by a certain tolerance. And discard it as a defective product.

A printed wiring board is manufactured by, for example, a subtractive method. That is, first, a prepreg is superposed on the outside (surface) of a core material provided inside and on the surface with a plurality of circuits serving as an inner layer circuit and a test pattern, and a metal foil is superimposed on the outside (surface) of the prepreg. Next, the core material, the prepreg, and the metal foil are stacked and heated and pressed (laminated press molding),
The prepreg is cured to form an insulating layer (dielectric layer), and the core material, the insulating layer and the metal foil are bonded and integrated by curing the prepreg. In this way, a metal foil-clad laminate having an inner layer circuit having a metal foil in the outermost layer and an inner layer circuit therein is formed. Next, after making a hole in the metal foil-clad laminate containing the inner layer circuit to form through holes and via holes, plating is applied to form through hole plating and via hole plating, and then the outermost metal layer The foil is subjected to a circuit forming process such as etching to form an outer layer circuit. In this way, a printed wiring board in which the outer layer circuit and the plurality of inner layer circuits are stacked via the insulating layer can be formed. The cause of the impedance value of the inner layer circuit being out of a predetermined allowable range from the design value may be excessive etching during pattern formation of the inner layer circuit (over-etching), defective flow of resin at the time of lamination, or the like. Also, it is conceivable that the thickness of the insulating layer formed between the inner layer circuit and the outer layer circuit becomes uneven.

As described above, there are two methods for checking whether or not the impedance value of the inner layer circuit of the printed wiring board is within a certain allowable range from the design value. This inspection can only be performed after formation. That is, as shown in FIG. 7, after forming the power ground circuit 11 and the through-hole plating 44 or the via-hole plating 41 electrically connected to the inner layer circuit or the test pattern 3 whose impedance value is to be measured, A measuring terminal portion (pad portion) 42 connected to the hole plating 44 and the via hole plating 41 is formed on the surface of the multilayer printed wiring board together with the outer layer circuit, and thereafter, the measuring terminals are externally (upper) of the printed wiring board. The inner layer circuit is inspected by bringing the probe 31 of the measuring device for measuring the impedance value into contact with the portion 42 almost vertically.

[0006]

However, in the above conventional example, after the outer layer circuit is formed on the metal foil-clad laminate containing the inner layer circuit, whether the impedance value of the inner layer circuit falls within a certain allowable range from the design value. In order to check whether or not the outer layer circuit must be formed on the metal foil-clad laminate with the inner layer circuit where the impedance value of the inner layer circuit is out of a certain allowable range from the design value, The printed wiring board is discarded as a defective product in a state of high added value in which the circuit is formed, which is wasteful, and the number of printed wiring boards manufactured is not stable. Therefore, there is a problem that the manufacturing cost of the printed wiring board is increased and the manufacturing period is lengthened.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and can inspect the impedance value of an inner layer circuit during the manufacture of a printed wiring board, and can reduce the manufacturing cost of the printed wiring board. It is also an object of the present invention to provide a metal foil-clad laminate with an inner layer circuit capable of shortening the manufacturing period of a printed wiring board, a printed wiring board formed using this metal foil-clad laminate with an inner layer circuit, and a method of manufacturing the same. It is the purpose.

[0008]

According to a first aspect of the present invention, there is provided a metal foil-clad laminate having an inner layer circuit, wherein a metal foil 21 is provided on one or both sides of a core portion 2 having an inner layer circuit 1 via an insulating layer 20. In the laminated metal foil-clad laminate with an inner layer circuit, a test pattern 3 for impedance measurement is formed on the same layer as the inner layer circuit 1 and at least one end of the test pattern 3 is exposed to an end face 16 of the core portion 2. It is characterized by the following.

A metal foil-clad laminate with an inner layer circuit according to a second aspect of the present invention is characterized in that, in addition to the configuration of the first aspect, a test pattern 3 is formed along the outer periphery of the inner layer circuit 1. It is a feature.

A metal foil-clad laminate with an inner layer circuit according to a third aspect of the present invention is the same as the first or second aspect, except that the test pattern 3 is formed with a predetermined circuit resistance value. It is a feature.

According to a fourth aspect of the present invention, there is provided a metal foil-clad laminate with an inner circuit according to any one of the first to third aspects. The reference circuit 4 serving as a reference is exposed on the end face 16 of the core portion 2.

According to a fifth aspect of the present invention, there is provided a metal foil-clad laminate with an inner layer circuit according to the fourth aspect of the present invention. , A notch 5 is formed in the reference circuit 4.

According to a sixth aspect of the present invention, there is provided a metal foil-clad laminate with an inner layer circuit according to any one of the first to fifth aspects, wherein the impedance value of the test pattern 3 is a certain allowable value from a design value. It is characterized in that it is confirmed that it is within the range.

A printed wiring board according to a seventh aspect of the present invention is formed by forming an outer layer circuit 8 from the metal foil 21 of the metal foil-clad laminate containing the inner layer circuit according to any one of the first to sixth aspects. It is characterized by the following.

According to a method of manufacturing a printed wiring board according to claim 8 of the present invention, a probe 31 is provided on an exposed end of the test pattern 3 of the metal foil-clad laminate having an inner layer circuit according to any one of claims 1 to 6. , The impedance value of the test pattern 3 is measured, and the metal foil 2 of the metal foil-clad laminate with the inner layer circuit in which the impedance value of the test pattern 3 is within a certain allowable range from the design value.
It is characterized in that a circuit 8 of an outer layer is formed from No. 1.

[0016]

Embodiments of the present invention will be described below.

The core portion 2 of the present invention is formed to have an inner layer circuit (inner layer pattern) 1 on one or both of the inside and the surface. The inner layer circuit 1 includes a signal circuit (signal pattern) 10 for transmitting a signal and a power ground circuit (power ground pattern) 11 serving as a power supply path or a ground. The reference circuit 3 serves as a voltage reference when the impedance value of the reference numeral 3 is measured. Also,
The core part 2 is provided with a test pattern 3. The test pattern 3 is a circuit whose impedance value is measured in order to inspect whether or not the impedance value of the signal circuit 10 is within a certain allowable range from the design value. Are provided in the same layer. Therefore, when the signal circuit 10 to be inspected is formed in a plurality of layers, the test patterns 3 are also formed in a plurality of layers corresponding to the signal circuits 10 to be inspected, respectively.

As the core 2, a circuit board (multilayer printed wiring board) conventionally used as an inner layer material or a core material in the production of a multilayer printed wiring board can be used as it is. Further, in forming the core portion 2, for example, the following subtractive method can be adopted, but the present invention is not limited to this, and another conventional method for manufacturing a multilayer printed wiring board may be adopted. good.

In forming the core portion 2 having the inner layer circuit (circuit to be the inner layer circuit 1) 1 and the test pattern 3 on only one surface, for example, the following can be performed. First, a metal foil is overlapped on one or both sides of the prepreg, and then the prepreg and the metal foil are stacked and heated and pressurized to cure the prepreg, thereby forming the insulating layer 20 and curing the insulating layer 20 by curing the prepreg. And the metal foil are integrated to form a single-sided or double-sided metal foil-clad laminate. As the resin of the prepreg, for example, any resin conventionally used in the production of prepreg, such as an epoxy resin or a phenol resin, can be used. Further, as the base material of the prepreg, for example, any base material conventionally used in the production of prepreg, such as glass woven fabric, glass nonwoven fabric, and paper, can be used. Furthermore, as the metal foil, any metal foil conventionally used for manufacturing a metal foil-clad laminate such as a copper foil can be used.

Next, an inner layer circuit 1 and a test pattern 3 are formed by performing a circuit forming step on the metal foil of the metal foil-clad laminate. The circuit forming step can use a conventional method. For example, first, a resist film is disposed over the entire surface of a metal foil, and a mask on which a desired circuit pattern is formed is disposed on the surface of the resist film. Next, the resist film is exposed through a mask to cure the light-irradiated portion. Next, after removing the mask, the uncured portion of the resist film is removed. Next, the metal foil not covered with the cured portion of the resist film is removed by etching. Thereafter, by peeling off the resist film, the inner layer circuit 1 and the test pattern 3 can be formed with the metal foil remaining on the insulating layer 20. Thereafter, if necessary, the inner layer circuits 1 are electrically connected to each other by through-hole plating or the like, so that the inner layer circuits 1 and the test patterns 3 are formed only on one surface.
Can be formed.

In forming the core portion 2 having the inner layer circuit 1 and the test pattern 3 in two layers, the inside and the surface, for example, the following can be performed. First, after forming the core portion 2 having the inner layer circuit 1 on only one surface in the same manner as described above, a prepreg is laminated on the surface of the core portion 2 and a metal foil is laminated on the surface of the prepreg. At this time, a resin may be applied instead of overlapping the prepregs. Next, the core 2, the prepreg, and the metal foil are stacked and heated and pressed to cure the prepreg to form the insulating layer 20, and the core 2, the insulating layer 20, and the metal foil are integrated by curing the prepreg. And stack. Next, the same circuit forming process as described above is performed on the metal foil to form the inner layer circuit 1 and the test pattern 3.
Thereafter, if necessary, the inner layer circuits 1 are electrically connected to each other by through-hole plating or the like, so that the core portion 2 having the inner layer circuit 1 and the test pattern 3 can be formed in two layers on the inside and the surface. .

Further, a step of laminating a metal foil via a prepreg on the surface of the core portion 2 with respect to the core portion 2 having the inner layer circuit 1 and the test pattern 3 in the two layers of the inside and the surface as described above; The step of forming a circuit on the metal foil and, if necessary, the step of connecting by through-hole plating are repeated a desired number of times, whereby the inner layer circuit 1 and the test pattern 3 are provided in three or more layers on the inside and the surface. The core part 2 can be formed. Incidentally, one test pattern 3 may be formed on one layer, or a plurality of test patterns may be formed on one layer. The shape of the test pattern 3 is arbitrary, and for example, can be formed as a straight line.

The test pattern 3 of the core portion 2 may be provided in a portion which remains in the product when it is processed into a product such as a metal foil-clad laminate or a printed wiring board with an inner layer circuit described later, or may be provided in the product. May be provided on the discarded substrate portion, which is a portion that does not remain on the substrate. Further, as shown in FIG. 3, it is preferable that the test pattern 3 is formed in a portion of the core portion 2 where the inner layer circuit 1 is not formed, so that the test pattern 3 is mixed with the inner layer circuit 1. In comparison with the above, when the impedance measurement is performed using the test pattern 3, the influence of the inner layer circuit 1 can be reduced, and an accurate measurement result can be obtained. Further, the test pattern 3 indicates the inner circuit 1 (where the inner circuit 1 is formed).
Is preferably formed along the outer periphery of
As shown in the figure, when the portion where the inner layer circuit 1 is formed is rectangular in plan view and the test pattern 3 is a straight line shape, the test pattern 3 is the outer periphery of the portion where the inner layer circuit 1 is formed. Is preferably formed along one side. By forming the test pattern 3 along the outer periphery of the inner layer circuit 1 in this way, the same impedance value as the wiring impedance of the inner layer circuit 1 can be measured by the test pattern 3. That is, the wiring impedance of the final product can be measured by the test pattern 3.

The circuit resistance of the test pattern 3 is set to a predetermined value according to the type of a printed wiring board to be described later formed using the core 2. For example, if the printed wiring board is used for a notebook computer, the circuit resistance of the test pattern 3 can be formed to 55Ω, and the printed wiring board is used for a memory used as a main storage device. Test pattern 3
Can be formed at 28Ω, 40Ω or 56Ω. As described above, the test pattern 3 is formed to have a predetermined circuit resistance value in accordance with the type of the printed wiring board formed by using the core portion 2, thereby stably operating under the condition that the inner layer circuit 1 is used as an electronic circuit. It is possible to confirm whether to do.

The test pattern 3 of the present invention is formed to be longer than the conventional test pattern.
As a result, as shown in FIG. 2, one end or both end surfaces of the test pattern 3
Is formed so as to be substantially flush with the end face 16 of the power supply ground circuit 11 of the inner layer circuit 1.
The power supply ground circuit is formed so as to be longer than the conventional power supply ground circuit, so that one end or both end surfaces of the power supply ground circuit 11 are almost flush with the end surface 16 of the core portion 2 as the contact terminal portion 17. It is formed so as to be exposed. The signal circuit 10 of the inner layer circuit 1 is the end face 1 of the core 2.
6 is preferably formed so as not to be exposed. further,
The width dimensions of the signal circuit 10, the power ground circuit 11, and the test pattern 3, the thickness of the insulating layer 20, etc., so that the impedance values of the signal circuit 10, the power ground circuit 11, and the test pattern 3 become constant values (design values). Is designed.

The metal foil-clad laminate with the inner layer circuit according to the present invention is provided on one or both sides of the core 2 with an insulating layer 2.
0 is formed, and a solid metal foil 21 is formed on the outer surface (front surface) of each insulating layer 20. The formation of such a metal foil-clad laminate with an inner layer circuit can be performed, for example, as follows. First, a prepreg is superimposed on one or both surfaces of the core portion 2 and a metal foil 21 is superimposed on the surface of each prepreg. The same prepreg and metal foil 21 as described above can be used. Further, a resin may be applied instead of overlapping the prepregs. Next, the core part 2
The prepreg and the metal foil 21 are stacked and heated and pressurized to harden the prepreg to form the insulating layer 20, and the core 2, the insulating layer 20 and the metal foil 21 are integrally laminated by curing the prepreg. In this way, it is possible to form a metal foil-clad laminate with an inner circuit in which the metal foil 21 is laminated on one or both sides of the core portion 2 via the insulating layer 20.

In the printed wiring board of the present invention, an outer layer circuit 8 is formed from the metal foil 21 by subjecting the metal foil 21 of the metal foil-clad laminate containing the inner layer circuit to the same circuit forming process as described above. Before the circuit forming process is performed on the metal foil 21 of the metal-foil-clad laminate including the inner layer circuit, the signal circuit 10 formed on the core 2 has a certain tolerance from a design value. (For example, a deviation within ± 10%) is inspected. In this inspection method, the impedance value of the test pattern 3 provided in the core part 2 is measured by a known impedance measuring instrument, and the impedance value of the test pattern 3 is out of a predetermined allowable range from a design value. The board regards the impedance value of the signal circuit 10 formed on the same layer as the test pattern 3 as being out of a predetermined allowable range from the design value and discards it as a defective product. Do not do it. On the other hand, in the metal foil-clad laminate with the inner layer circuit in which the impedance value of the test pattern 3 is within a certain allowable range from the design value, the impedance value of the signal circuit 10 formed in the same layer as the test pattern 3 is also designed. The product is regarded as being within a certain allowable range from the value and is regarded as a non-defective product, and the next circuit forming step is performed.

In this way, based on the measurement result of the impedance value of the test pattern 3, the metal foil-clad laminate with the inner layer circuit having a high possibility that the impedance value of the signal circuit 10 is out of a predetermined allowable range from the design value. Is inspected and discarded, and the circuit forming process is performed only on the metal foil-clad laminate with the inner layer circuit, which is unlikely to have the impedance value of the signal circuit 10 deviating from a design value within a certain allowable range. Note that the above inspection may be performed before forming the insulating layer 20 and the metal foil 21 on the core portion 2.
It is better to perform the inspection after providing the insulating layer 20 and the metal foil 21 in a state close to the time of using the printed circuit board.
Is preferable because the inspection can be performed.

As a method of measuring the impedance value of the test pattern 3, TDR (Time Domain Reflection) can be adopted. FIG. 4 shows the impedance measuring device.
As shown in FIG. 1, the apparatus comprises a probe 31, an oscilloscope 32, and a step pulse generator 33. Then, when measuring the impedance value of the test pattern 3, first, as shown in FIG.
Then, the probe 31 is brought close to the side (side) of the metal foil-clad laminate with the inner layer circuit so that one contact 35 of the probe 31 contacts the contact terminal 15 of the test pattern 3 and the probe 31 Is brought into contact with the contact terminal portion 17 of the power ground circuit 11. Next, the step pulse generated by the step pulse generator 33 is applied to the test pattern 3 from the contact 35 of the probe 31.
To enter. When a step pulse is input to the test pattern 3 as described above, a reflected wave is generated. Next, the reflected wave and the traveling wave are time-divided by the oscilloscope 32 to obtain a reflection coefficient ρ. Then, the impedance value Zo of the test pattern 3 is calculated by the following equation (1).

Zo = (1 + ρ) / (1-ρ) × Zr (1) where Zr is a reference impedance determined by the frequency of the step pulse.

After the impedance value of the test pattern 3 is obtained in this manner, it is checked whether the value falls within a predetermined allowable range from a design value, and the signal provided on the same layer as the test pattern 3 from which the impedance value is obtained is determined. The inspection of the circuit 10 is performed. Before forming the circuit 8 in the outer layer, it is confirmed whether the impedance values of the test pattern 3 and the signal circuit 10 are within a certain allowable range from the design value, and the quality is checked. It is guaranteed.

In the metal foil-clad laminate with an inner layer circuit according to the present invention, a test pattern 3 is provided on the same layer as the signal circuit 10 on the core section 2 having the signal circuit 10 as the inner layer circuit 1. The test circuit 3 is formed so as to be exposed on the reference pattern 16 and a reference circuit 4 serving as a voltage reference when measuring the impedance value of the test pattern 3.
Are provided so as to be exposed on the end face 16 of the core portion 2, so that the contacts 35, 36 of the probe 31 of the impedance measuring device
Can be easily brought into contact with the test pattern 3 and the reference circuit 4 by approaching from the side of the metal foil-clad laminate with the inner layer circuit, and the circuit 8 and the through hole of the outer layer are not formed (before forming). Even if there is, the impedance value of the test pattern 3 can be measured, and it can be inspected whether the impedance value of the signal circuit 10 is within a certain allowable range from the design value.

Further, in the metal foil-clad laminate with an inner layer circuit and the method of manufacturing a printed wiring board using the same according to the present invention,
The impedance value of the test pattern 3 is measured as described above, and a circuit is formed on the metal foil 21 only for the metal foil-clad laminate with the inner layer circuit where the impedance value of the test pattern 3 is within a certain allowable range from the design value. Since the circuit 8 of the outer layer is formed by applying the method, the metal foil-clad laminate with the inner layer circuit, which is considered to be defective due to the high possibility that the impedance value of the signal circuit 10 is out of a predetermined allowable range from the design value, is formed in the next step of circuit formation. This eliminates the need to send to the process, thereby reducing waste. Therefore, the manufacturing cost of the printed wiring board can be reduced and the number of manufactured printed wiring boards can be stabilized.

The printed wiring board of the present invention manufactured as described above can be used as the core part 2 to form the metal foil-clad laminate of the present invention containing an inner layer circuit. The circuit 8 becomes the inner layer circuit 1 provided on the surface of the core section 2. Also, the above test pattern 3
The impedance value of the test pattern 3 is measured after completion of the printed wiring board. If the impedance value of the test pattern 3 is out of the predetermined range, that is, if the impedance value of the signal circuit 10 is out of the predetermined range. Defective printed wiring boards that can be considered can also be eliminated.

FIGS. 6A and 6B show another embodiment. The metal foil-clad laminate with the inner layer circuit has a cutout 5 having a substantially semicircular shape in a plan view at the end of the reference circuit 4 near the end face 16 of the core 2. The notch 5 is a contact terminal portion 15 which is an exposed portion of the test pattern 3.
The reference circuit 4 is formed so as not to be exposed at the end face 16 of the core portion 2 at the position of the cutout 5. Other configurations are the same as in the above embodiment.

In the probe shown in FIG. 2, when the insulating layer between the test pattern 3 and the reference circuit 4 is thin and the distance between the test pattern 3 and the reference circuit 4 is small, the probe 31 which is to be brought into contact with the test pattern 3 is used. The contact 35 of the reference circuit 4
May accidentally come into contact with each other and cause a short circuit, making it impossible to measure the impedance value. Therefore, as shown in FIGS. 6A and 6B, a notch 5 is provided in the reference circuit 4 near the contact terminal 15 of the test pattern 3 so that a part of the reference circuit 4 is not exposed. Test pattern 3
The contact 35 of the probe 31 that attempts to contact the test pattern 3 is less likely to accidentally contact the reference circuit 4 even if the distance between the probe 31 and the reference circuit 4 is small.
The contact 35 can be stably brought into contact with the contact terminal portion 15 of the test pattern 3 without reducing the thickness of the test pattern 5, and the impedance value can be easily measured.

[0037]

As described above, the invention according to claim 1 of the present invention relates to a metal foil-clad laminate with an inner layer circuit in which a metal foil is laminated on one or both sides of a core portion having an inner layer circuit via an insulating layer. Since a test pattern for impedance measurement is formed on the same layer as the inner layer circuit and at least one end of the test pattern is exposed on the end face of the core, the probe of the impedance measuring instrument is brought close to the side to easily contact the test pattern. It is possible to measure the impedance value of the test pattern before forming the outer layer circuit during the manufacture of the printed wiring board, and the impedance value of the inner layer circuit is within a certain allowable range from the design value. It can be checked whether or not it is. Therefore, the circuit of the outer layer is not formed on the metal foil-clad laminate with the inner layer circuit in which the impedance value of the inner layer circuit is out of a predetermined allowable range from the design value. The manufacturing cost of the wiring board can be reduced, and the manufacturing period of the printed wiring board can be shortened.

According to the second aspect of the present invention, since the test pattern is formed along the outer periphery of the inner layer circuit, the same impedance value as the wiring impedance of the inner layer circuit can be measured by the test pattern. That is, the wiring impedance of the final product can be measured by the test pattern.

Further, according to the third aspect of the present invention, since the test pattern is formed with a predetermined circuit resistance value, it can be confirmed whether or not the circuit operates stably under the condition that the inner layer circuit is used as an electronic circuit. Thus, it is possible to guarantee that the electronic circuit operates stably.

According to the invention of claim 4 of the present invention, a reference circuit serving as a voltage reference when measuring the impedance value of the test pattern is exposed at the end face of the core portion. Can be easily brought into contact with the test pattern and the reference circuit by approaching from the side, and the impedance value of the test pattern can be measured before forming the circuit of the outer layer during the manufacture of the printed wiring board, It is possible to inspect whether the impedance value of the inner layer circuit is within a certain allowable range from the design value. Therefore, the circuit of the outer layer is not formed on the metal foil-clad laminate with the inner layer circuit in which the impedance value of the inner layer circuit is out of a predetermined allowable range from the design value. The manufacturing cost of the wiring board can be reduced, and the manufacturing period of the printed wiring board can be shortened.

According to the invention of claim 5 of the present invention, a notch is formed in the reference circuit near the end of the test pattern exposed at the end face of the core portion. This makes it difficult for the contact to come into contact with the reference circuit, thereby preventing a short circuit. Even when the test pattern and the reference circuit are close to each other, the impedance of the test pattern can be easily measured.

According to the invention of claim 6 of the present invention, since it is confirmed that the impedance value of the test pattern is within a certain allowable range from the design value, the impedance value of the inner layer circuit is also determined from the design value. An outer layer circuit is formed for a metal foil-clad laminate with an inner layer circuit in which the impedance value of the inner layer circuit is out of a certain allowable range from the design value, which can be regarded as falling within a certain allowable range. This eliminates waste of materials and processes, reduces the manufacturing cost of the printed wiring board, and shortens the manufacturing period of the printed wiring board.

According to a seventh aspect of the present invention, since the outer layer circuit is formed from the metal foil of the metal foil-clad laminate containing the inner layer circuit according to any one of the first to sixth aspects, the impedance of the inner layer circuit is improved. It is possible to reduce that the value deviates from a design value within a certain allowable range, and it is possible to form a device having impedance characteristics close to the design value.

According to the invention of claim 8 of the present invention, the probe is brought into contact with the exposed end of the test pattern of the metal foil-clad laminate with the inner layer circuit according to any one of claims 1 to 6 by: Since the impedance value of the test pattern is measured and the outer layer circuit is formed from the metal foil of the metal foil clad laminate with the inner layer circuit where the impedance value of the test pattern is within a certain allowable range from the design value,
By measuring the impedance value of the test pattern before forming the outer layer circuit, it is possible to inspect whether or not the impedance value of the inner layer circuit is within a certain allowable range from the design value. The circuit of the outer layer is not formed for the metal foil-clad laminate with the inner layer circuit where the impedance value of the circuit is out of the allowable range from the design value. And the manufacturing period can be shortened.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of an embodiment of a metal foil-clad laminate with an inner layer circuit of the present invention.

FIG. 2 is a front view showing an example of an embodiment of a metal foil-clad laminate with an inner layer circuit of the present invention.

FIG. 3 is a plan view showing an example of a core material of a metal foil-clad laminate having an inner layer circuit according to the present invention.

FIG. 4 is a schematic diagram illustrating an example of an impedance measuring device.

FIG. 5 is a front view showing an example of an embodiment of the printed wiring board of the present invention.

6A and 6B show another example of the embodiment of the metal foil-clad laminate with an inner layer circuit of the present invention, wherein FIG. 6A is a front view and FIG. 6B is a plan view of a reference circuit.

FIG. 7 is a schematic view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner layer circuit 2 Core part 3 Test pattern 5 Notch part 8 Outer layer circuit 16 End face 20 Insulating layer 21 Metal foil 31 Probe

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tokio Yoshimitsu 1048 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Inventor Koji Kurata 1048 Kadoma Kadoma Kadoma City, Osaka Matsushita Electric Works Co., Ltd. F term (for reference) 5E317 AA02 BB01 BB11 CC53 CD29 GG17 5E338 AA03 BB75 CC01 CC10 CD14 CD33 EE11 EE32 EE33 5E346 AA05 AA06 AA12 AA14 AA15 BB01 BB11 CC02 CC08 CC31 DD02 DD32 EE01 GG28GG33 H33

Claims (8)

[Claims] 1. A metal foil-clad laminate with an inner layer circuit in which a metal foil is laminated on one or both sides of a core portion having an inner layer circuit via an insulating layer, a test pattern for impedance measurement is formed on the same layer as the inner layer circuit. A metal foil-clad laminate with an inner layer circuit, wherein the laminate is formed and at least one end of a test pattern is exposed to an end face of a core portion. 2. The metal foil-clad laminate with an inner layer circuit according to claim 1, wherein the test pattern is formed along the outer periphery of the inner layer circuit. 3. The metal foil-clad laminate with an inner layer circuit according to claim 1, wherein the test pattern is formed with a predetermined circuit resistance value. 4. The inner layer circuit according to claim 1, wherein a reference circuit serving as a voltage reference when measuring the impedance value of the test pattern is exposed at an end face of the core portion. Metal foil clad laminate. 5. The metal foil-clad laminate with an inner layer circuit according to claim 4, wherein a cutout is formed in the reference circuit near the end of the test pattern exposed on the end face of the core. . 6. The metal foil with an inner layer circuit according to claim 1, wherein it is confirmed whether the impedance value of the test pattern is within a certain allowable range from the design value. Upholstered laminate. 7. A printed wiring board comprising an outer layer circuit formed from the metal foil of the metal foil-clad laminate with the inner layer circuit according to claim 1. 8. An impedance value of the test pattern is measured by bringing a probe into contact with an exposed end of the test pattern of the metal foil-clad laminate with an inner layer circuit according to claim 1. A method for manufacturing a printed wiring board, wherein an outer layer circuit is formed from a metal foil of a metal foil-clad laminate with an inner layer circuit in which the impedance value of a pattern falls within a predetermined allowable range from a design value.