JP2002286786A - Impedance measuring circuit pattern and impedance measuring circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impedance measuring circuit pattern capable of executing accurately inspection of a signal circuit pattern. SOLUTION: This impedance measuring circuit pattern A has a measuring region 1 where impedance is to be measured. The circuit widths of regions 2, 3 other than the measuring region 1 are formed larger than the circuit width of measuring region 1. A direct current resistance component in the regions other than the measuring region 1 can be reduced by widening the circuit widths of the regions 2, 3 other than the measuring region 1, and impedance in the measuring region 1 can be measured accurately by suppressing floating of a measuring waveform acquired by a TDR method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impedance measuring circuit pattern for inspecting the impedance of a signal circuit pattern and an impedance measuring circuit board provided with the circuit pattern.

[0002]

2. Description of the Related Art In a circuit board used for electronic equipment, etc.,
Impedance matching between a signal circuit pattern (circuit) provided on a circuit board and a signal transmitting the signal circuit pattern is performed. In particular, a signal circuit pattern for transmitting a high-frequency signal (high-speed signal) is used. In some cases, this impedance matching is important. Therefore, the signal circuit pattern of the circuit board is designed so that impedance matching with the signal transmitted therethrough can be obtained, and the circuit board is designed so that the impedance of the signal circuit pattern falls within a certain allowable range from its design value. It has been inspected and commercialized. If the impedance of the signal circuit pattern is out of a certain allowable range, the signal circuit pattern is discarded as a defective product.

Conventionally, when inspecting whether or not the impedance of a signal circuit pattern is within a predetermined allowable range from a design value, mainly, a TDR (Time Domain Ref) is used.
rectometry) method is used. In this method, an input signal such as a pulse signal is input to a transmission circuit pattern including a signal circuit pattern and a reference ground circuit pattern, a reflection signal in the transmission circuit pattern is detected, and a reflection coefficient obtained from the reflection signal is calculated. By measuring the impedance of the transmission circuit pattern and comparing the actual measurement value with the design value, it is checked whether the impedance of the signal circuit pattern is within a certain allowable range from the design value. Because In the TDR method, the impedance distribution in the transmission circuit pattern can be known by continuously observing the state of reflection over the repetition time interval of the input signal.

In the above-described TDR method, it is necessary to use an impedance measuring device for inputting an input signal to a transmission circuit pattern or detecting a reflected signal, and electrically connect the impedance measurement device to the transmission circuit pattern. There is. Normally, the reference ground circuit pattern exists as a solid surface on the surface of the circuit board, and a probe or the like connected to the impedance measurement device is brought into contact with the reference ground circuit pattern, thereby connecting the impedance measurement device and the reference ground circuit pattern. It can be easily electrically connected. However, the signal circuit pattern is often present as an inner layer of a multilayer circuit board. In this case, in order to electrically connect the signal circuit pattern to the impedance measuring device, the signal circuit pattern is required to contact a probe or the like. Must be exposed outside the circuit board. In exposing the signal circuit pattern to the outer surface of the circuit board, a through hole or the like which reaches the signal circuit pattern by opening the surface (upper surface or lower surface) of the circuit board or is formed on the end surface (peripheral surface) of the circuit board. A method of exposing the signal circuit pattern is conceivable, but in any case, the signal circuit pattern is exposed outside the circuit board as a product, which is not preferable because a short circuit or the like may occur.

Therefore, apart from the signal circuit pattern of the circuit board, a circuit pattern (inspection pattern) for impedance measurement is used.
Has been proposed. The impedance measurement circuit pattern is a circuit pattern formed having a measurement region and an introduction region. By measuring the impedance of the measurement region by the TDR method instead of the signal circuit pattern to be inspected, Inspection of the signal circuit pattern is performed indirectly.
That is, when inspecting whether or not the impedance of the signal circuit pattern is within the allowable range from the design value using the impedance measurement circuit pattern, the transmission circuit pattern including the impedance measurement circuit pattern and the reference ground circuit is used. Input signal such as a pulse signal, and detects a reflected signal in the transmission circuit pattern.
The impedance of the transmission circuit pattern is obtained using the reflection coefficient obtained from the reflection signal, and the impedance of the measurement area is compared with its design value. If the impedance of the measurement area falls within the allowable range, it is considered that the impedance of the signal circuit pattern also falls within the allowable range. The impedance of the circuit pattern is also considered to be out of the allowable range. In this case, the circuit board for impedance measurement is discarded as a defective product.

The use of such an impedance measuring circuit pattern prevents the signal circuit pattern from being exposed to the outside and prevents a short circuit or the like from occurring on a circuit board as a product. .

The above-described impedance measuring circuit pattern is provided on the same layer as the signal circuit pattern whose impedance is to be inspected. Therefore, when the signal circuit pattern whose impedance is to be inspected is in the inner layer, the impedance is measured. The measurement circuit pattern is also formed in the inner layer. The measurement area is formed near the signal circuit pattern whose impedance is to be inspected in order to inspect the signal circuit pattern with high accuracy.

In order to electrically connect the impedance measuring circuit pattern to the impedance measuring device,
Terminal part (contact surface) for contacting probe etc.
Is formed in the introduction area, and the surface (upper surface or lower surface) of the impedance measuring circuit board at a position corresponding to the terminal portion
The terminal section is exposed outside the impedance measurement circuit board by forming a through hole or the like that reaches the terminal section by opening the terminal section, or by exposing the terminal section to the end face of the impedance measurement circuit board. ing. And
In this case, by appropriately setting the length of the introduction area,
Regardless of the position of the measurement area, the terminal portion can be formed at almost any place on the impedance measurement circuit board.

FIG. 7 shows an example of a conventional circuit board B for impedance measurement. In the impedance measurement circuit board B, an impedance measurement circuit pattern A is provided in an inner layer, and two reference ground circuit patterns 10 are formed on an upper layer and a lower layer with an insulating layer 6 interposed therebetween.
The impedance measurement circuit pattern A is composed of a measurement area 1 and an introduction area 2.
Is connected to one end of the introduction region 2. One end of the introduction region 2 (the end that is not connected to the measurement region 1) is formed as a terminal portion 4 for contacting a contact pin or the like of a probe connected to the impedance measuring device. The measurement region 1 and the introduction region 2 have the same circuit width w, and the circuit pattern A for impedance measurement is formed in a straight line.

When measuring the impedance of the measurement area 1 of the impedance measurement circuit pattern A in such an impedance measurement circuit board B, the impedance measurement circuit board B must be positioned at a position corresponding to the terminal portion 4. The contact hole of the probe connected to the impedance measuring device is inserted into the through hole to contact the terminal portion 4 and the other contact pin of the probe is connected to the reference ground circuit pattern. 10 and then the above TDR
The impedance of the measurement area 1 is measured by the method.
When the terminal portion 4 reaches the end face of the impedance measuring circuit board B, it is not necessary to provide a through hole.

[0011]

However, in the TDR method, as the length of the circuit pattern to be measured becomes longer, the influence of the DC resistance component contained in the circuit pattern increases, and the measured waveform becomes closer to the end of the circuit pattern. It has the property that it rises and rises, and the apparent measured value increases. For this reason, in the conventional impedance measurement circuit pattern A, when the distance from the terminal portion 4 to the measurement region 1 is long, that is, when the introduction region 2 is long, the impedance of the measurement region 1 can be accurately measured. There is a problem in that a value cannot be obtained and a signal circuit pattern cannot be inspected with high accuracy. In particular, when the terminal portion 4 is exposed on the end face of the circuit board B for impedance measurement, the length of the introduction region 2 becomes very long, so that the accuracy of the inspection of the signal circuit pattern is extremely reduced. .

When one impedance measurement circuit board B is formed of a plurality of circuit boards, a plurality of measurement areas 1 are often provided corresponding to the signal circuit patterns of each circuit board. If a plurality of measurement areas 1 are electrically connected by a conductor to form one impedance measurement circuit pattern A, and the impedance of the plurality of measurement areas 1 is measured in one measurement operation, the signal circuit pattern inspection can be performed at high speed. And efficiency can be improved. However, also in this case, since the impedance measurement circuit pattern A is necessarily long, sufficient inspection accuracy cannot be obtained for the same reason as described above.

The present invention has been made in view of the above points, and has as its object to provide an impedance measuring circuit pattern and an impedance measuring circuit board capable of accurately inspecting a signal circuit pattern. It is.

It is another object of the present invention to provide an impedance measuring circuit pattern and an impedance measuring circuit board capable of simultaneously and accurately inspecting a plurality of signal circuit patterns.

[0015]

An impedance measuring circuit pattern according to a first aspect of the present invention is an impedance measuring circuit pattern having a measuring area in which impedance is measured, and the impedance measuring circuit pattern other than the measuring area. Region 2,
3 is formed to have a larger circuit width than the circuit width of the measurement area 1.

The circuit pattern A for impedance measurement according to a second aspect of the present invention is the same as that of the first aspect, except that the terminal portion 4 formed in the area 2 other than the measurement area 1 is connected to the measurement area 1. The circuit width of the regions 2 and 3 between them is formed larger than the circuit width of the measurement region 1.

Further, the circuit pattern A for impedance measurement according to claim 3 of the present invention, in addition to the structure of claim 1 or 2, has the following features:
The circuit width is formed to be larger than the circuit width of the measurement area 1.

According to a fourth aspect of the present invention, there is provided a circuit pattern A for impedance measurement according to any one of the first to third aspects, wherein the impedance of the regions 2 and 3 other than the measurement region 1 is defined as a reference impedance. It is characterized by being matched.

According to a fifth aspect of the present invention, in addition to the configuration of the fourth aspect, the impedance measuring circuit pattern A is characterized in that the impedance of the terminal portion 4 is used as a reference impedance.

Further, the circuit pattern A for impedance measurement according to claim 6 of the present invention is characterized in that, in addition to the configuration of claim 4, the impedance of the measurement area is used as a reference impedance.

A circuit board B for impedance measurement according to a seventh aspect of the present invention is a circuit board B for impedance measurement provided with the circuit pattern A for impedance measurement according to any one of the first to sixth aspects. The present invention is characterized in that at least one of the upper and lower conductors 5 in the regions 2 and 3 other than the region 1 is partially or entirely removed.

An impedance measuring circuit board B according to an eighth aspect of the present invention is an impedance measuring circuit board B provided with the impedance measuring circuit pattern A according to any one of the first to sixth aspects. The insulating layer 6 adjacent to the regions 2 and 3 other than the region 1 is formed of a resin having a lower dielectric constant than the insulating layer 6 adjacent to the measuring region 1.

[0023]

Embodiments of the present invention will be described below.

FIGS. 1A and 1B show an example of an impedance measuring circuit board B of the present invention. The impedance measuring circuit board B is provided with a planar impedance measuring circuit pattern A as an inner layer as shown in FIG. The circuit pattern A for impedance measurement includes a measurement area 1 and an introduction area 2, and one end of the measurement area 1 is connected to one end of the introduction area 2. One end of the introduction region 2 (the end that is not connected to the measurement region 1) is formed as a terminal portion 4 for contacting a contact pin or the like of a probe connected to the impedance measuring device. Then, the measurement area 1 and the introduction area 2
Are formed in a linear shape having a constant circuit width, respectively, but the circuit width W of the introduction region 2 is formed larger than the circuit width w of the measurement region 1.

It is known that the DC resistance component of a circuit pattern formed of a conductor such as copper depends on the circuit width.
If the circuit patterns have the same length, the DC resistance component decreases as the circuit width increases (widens). Therefore, in the present invention, the circuit width W of the introduction region 2 is formed to be larger than the circuit width w of the measurement region 1.
The DC resistance component of the introduction region 2 can be reduced. Therefore, even if the impedance of the measurement area 1 of the impedance measurement circuit pattern A is measured by the TDR method, the influence of the DC resistance component of the introduction area 2 can be reduced, and the rise of the measurement waveform in the measurement area 1 can be suppressed. Can be done. Therefore, measurement area 1
Thus, it is possible to obtain an accurate measurement value of the impedance of the signal circuit and accurately inspect the signal circuit pattern.

It is sufficient that the circuit width W of the introduction region 2 is so large that its DC resistance component can be neglected, and the length of the circuit pattern A for impedance measurement, the length of the introduction region 2,
The length and the circuit width of the measurement area 1 and the size of the circuit board B for impedance measurement may be appropriately set, but the circuit width W of the introduction area 2 is at least three times or more the circuit width w of the measurement area 1. Is preferably formed, and if less than this,
There is a possibility that the influence of the DC resistance component of the introduction region 2 cannot be reduced. Further, since the smaller the DC resistance component of the introduction region 2 is, the more preferable, the upper limit of the circuit width W of the introduction region 2 is not particularly set.
May be set in consideration of the size and the like. As a result of the experiment, the length of the circuit pattern A for impedance measurement was 40
In the case of 0 mm, the circuit width W of the introduction region 2 is about 300 to 40
It has been found that the thickness is preferably about 0 μm.
It is not limited to this.

Incidentally, the impedance of the circuit pattern is affected by the cross-sectional shape of the circuit pattern.
If other conditions are the same, the impedance value decreases when the circuit width of the circuit pattern is increased. Therefore,
As described above, when the circuit width W of the introduction region 2 is increased, the impedance of the introduction region 2 is reduced. However, if the decrease is significant (large), the reduced region (introduction region 2) and the other regions The measurement area 1 is reflected by reflection, for example, reflection at the boundary between the terminal portion 4 and the probe.
, There is a possibility that sufficient measurement accuracy cannot be obtained due to the principle of the TDR method. Therefore, in order to avoid such a problem, it is preferable that an impedance serving as a reference is determined and a region other than the measurement region 1, that is, the introduction region 2 is matched with the reference impedance, thereby generating an unnecessary reflected signal. Can be suppressed, and the measurement accuracy can be increased.

In setting the reference impedance, there are a method of using the impedance of the terminal section 4 as the reference impedance and a method of using the impedance of the measurement area 1 itself as the reference impedance. The former is particularly effective when the region other than the measurement region 1 is adjacent to the terminal portion 4, while the latter is generally effective when the region other than the measurement region 1 is not adjacent to the terminal portion 4. It is. The impedance of the terminal section 4 is generally of a 50Ω type.

As described above, there are several methods for matching the impedance of the region other than the measurement region 1 with the reference impedance. However, as a simple method, the impedance is adjacent to the region other than the measurement region 1 (the introduction region 2). A method of making the insulating layer 6 larger than the insulating layer 6 adjacent to the measurement region 1 can be exemplified. That is, as shown in FIG. 1 (b), the reference ground circuit pattern 10 which is the conductor 5 is provided in the upper layer and the lower layer of the measurement area 1 with the insulating layer 6 interposed between the inner layer and the outer layer. As shown in FIG. 1C, a reference ground circuit pattern 10 which is a conductor 5 is provided one layer at a time on an outer layer via an insulating layer 6 in an upper layer and a lower layer of the introduction region 2. By removing the inner reference ground circuit pattern 10 at the position corresponding to the introduction region 2, the insulation layer 6 adjacent to the introduction region 2 is formed larger (thicker) than the insulation layer 6 adjacent to the measurement region 1. Is what is being done.

The thickness of the insulating layer 6 adjacent to the introduction region 2 can be formed to be two to four times the thickness of the insulating layer 6 adjacent to the measurement region 1, but is not limited to this range. Is appropriately set depending on the value of the reference impedance to be matched.

As another method for matching the impedance of the region other than the measurement region 1 with the reference impedance, the insulating layer 6 adjacent to the region other than the measurement region 1 (introduction region 2) may be insulated. A method of forming with a resin having a lower dielectric constant than the layer 6 can be exemplified. That is, a hole is formed by removing the insulating layer 6 adjacent to the introduction region 2 by countersinking or the like, and a resin having a lower dielectric constant than the insulating layer 6 adjacent to the measurement region 1 is embedded in the hole. For example, when the circuit board B for impedance measurement is formed of a glass-based epoxy resin material, the insulating layer 6 adjacent to the measurement region 1 is formed of epoxy resin, so that a material having a lower dielectric constant than this is used. It is preferable to form the insulating layer 6 adjacent to the introduction region 2 using a certain fluorine resin such as PTFE (polytetrafluoroethylene).

The dielectric constant of the insulating layer 6 adjacent to the introduction region 2 is 0.5 to 0.5 of the dielectric constant of the insulating layer 6 adjacent to the measuring region 1.
Although it can be formed to be 0.8 times, it is not limited to this range and is appropriately set according to the value of the reference impedance to be matched.

FIG. 2 shows another embodiment. As shown in FIG. 2A, an impedance measuring circuit board B according to this embodiment is configured such that an impedance measuring circuit pattern A is composed of two measurement areas 1, an introduction area 2, and a connection area 3. One end of the first measurement region 1a, which is one of the measurement regions 1, is connected to one end of the introduction region 2 and the other end of the first measurement region 1a is connected to one end of the connection region 3. The other end of the connection region 3 (the end not connected to the first measurement region 1a) is connected to the other measurement region 1
Is connected to one end of the second measurement region 1b, and one end of the introduction region 2 (the end not connected to the first measurement region 1a) is connected to a contact pin of a probe connected to the impedance measurement device. It is formed as a terminal portion 4 for contacting the like. In the impedance measurement circuit pattern A, since the two measurement regions 1 are connected by the connection region 3 to form a single circuit pattern, a plurality of measurement regions 1 can be formed in one measurement operation by the TDR method.
Can be measured, and the speed and efficiency of inspection of a plurality of signal circuit patterns can be improved.

In the above-described circuit pattern A for impedance measurement, both the measurement region 1, the introduction region 2 and the connection region 3 are formed in a linear shape having a constant circuit width. Is formed to be larger than the circuit width w of the measurement area 1 as in the embodiment shown in FIG. Also, the circuit width H of the connection region 3 is formed to be larger than the circuit width w of the measurement region 1. The reason why the circuit width W of the introduction region 2 is formed larger than the circuit width w of the measurement region 1 has been described above. However, the reason why the circuit width H of the connection region 3 is formed larger than the circuit width w of the measurement region 1 is also described. This is similar to the case of 2. That is, by forming the circuit width H of the connection region 3 larger than the circuit width w of the measurement region 1, the DC resistance component of the connection region 3 can be reduced, and the TDR
Even if the impedance of both measurement areas 1 is measured by the method, the influence of the DC resistance component of the connection area 3 can be reduced, and the rise of the measurement waveform in the measurement area 1 can be suppressed. Therefore, by connecting the plurality of measurement regions 1 at the connection region 3, the inspection of the plurality of signal circuit patterns can be performed at high speed and efficiency, but the impedance of the measurement region 1 can be accurately measured. The value can be obtained, and the inspection of the signal circuit pattern can be performed with high accuracy. Note that the connection region 3 is also preferably formed at least three times the circuit width w of the measurement region 1 for the same reason as the introduction region 2, and the DC resistance component of the connection region 3 is preferably as small as possible. Is not particularly set.

Further, the introduction region 2 in this embodiment
It is preferable to determine the reference impedance in the same manner as in FIG. 1 and match the reference impedance with the reference impedance. Thus, it is possible to suppress the occurrence of an unnecessary reflected signal and to increase the measurement accuracy. Although it is possible, it is preferable that the connection region 3 also determines a reference impedance in the same manner as the introduction region 2 and matches it with the reference impedance, thereby suppressing the generation of an unnecessary reflected signal and measuring accuracy. Can be increased. It is preferable that the connection region 3 is matched with the impedance of the measurement region 1 having the larger circuit width among the measurement regions 1 on both sides as a reference impedance. Note that the impedance of the measurement area 1 cannot be understood unless it is actually measured. However, the impedance is measured in advance on another substrate having a similar configuration, and a rough estimate is given.
The connection region 3 does not need to exactly match the reference impedance, and a deviation of about 10% is within an allowable range.

In order to match the impedance of the introduction region 2 and the connection region 3 with the reference impedance, the insulating layer 6 adjacent to the introduction region 2 and the connection region 3 is separated from the insulation layer 6 adjacent to the measurement region 1 in the same manner as described above. Can also be exemplified. That is, FIG.
As shown in FIG. 2B, a reference ground circuit pattern 10 as a conductor 5 is provided in two layers, an inner layer and an outer layer, via an insulating layer 6 in the upper layer and the lower layer of the measurement area 1.
As shown in (c), the upper and lower layers of the introduction region 2 and the connection region 3 are provided with a reference ground circuit pattern 10 as a conductor 5 on an outer layer with an insulating layer 6 interposed therebetween. As described above, the reference ground circuit pattern 1 of the inner layer is provided at positions corresponding to the introduction region 2 and the connection region 3.
0, the introduction region 2 and the connection region 3
Is formed larger (thicker) than the insulating layer 6 adjacent to the measurement region 1.

As another method for matching the impedances of the introduction region 2 and the connection region 3 to the reference impedance, an insulating layer 6 adjacent to the introduction region 2 and the connection region 3 may be used.
Can be exemplified by a resin having a lower dielectric constant than the insulating layer 6 adjacent to the measurement region 1. That is,
The insulating layer 6 adjacent to the introduction region 2 and the connection region 3 is removed by counterboring or the like to form a hole, and a resin having a lower dielectric constant than the insulating layer 6 adjacent to the measurement region 1 is embedded in the hole.

FIG. 3 shows another embodiment. The circuit board B for impedance measurement of this embodiment is such that four circuit boards serving as products are arranged on one substrate in a state where they are surface-mounted, and the product parts 15a to 15d serving as circuit boards are provided. It is composed of the surrounding substrate part 16. The product sections 15a to 15d include a plurality of signal circuit patterns 17a to 17d.
17d are formed, and the discard substrate portion 1
6 includes impedance measuring circuit patterns A1 to A3 for inspecting the signal circuit patterns 17a to 17d.
Is provided. The circuit pattern A1 for impedance measurement is formed in the same manner as that shown in FIG. 2, and includes two measurement areas 1, an introduction area 2, and a connection area 3. The first measurement region 1a is for inspecting the signal circuit pattern 17a of the product section 15a, and the first measurement region 1a and the signal circuit pattern 17a are provided in the same layer and substantially in parallel. The second measurement area 1b is for inspecting the signal circuit pattern 17b of the product section 15b,
b and the signal circuit pattern 17b are provided substantially in parallel in the same layer.

The circuit patterns A2 and A3 for impedance measurement are formed in the same manner as shown in FIG.
It comprises a measurement area 1 and an introduction area 2. The measurement region 1c of the impedance measurement circuit pattern A2 is for inspecting the signal circuit pattern 17c of the product part 15c, and the measurement region 1c and the signal circuit pattern 17c are provided in the same layer and substantially in parallel. The measurement area 1d of the impedance measurement circuit pattern A3 is for inspecting the signal circuit pattern 17d of the product section 15d.
d and the signal circuit pattern 17d are provided substantially in parallel in the same layer.

Further, the terminal portion 4 in the introduction region 2 of the impedance measurement circuit patterns A1 to A3 is exposed at the end face of the impedance measurement circuit board B by extending the introduction region 2.

In FIGS. 1 to 3, the signal circuit pattern is inspected by the TDR method in the same manner as in the conventional example. In the case of FIG. 3, after the inspection of the signal circuit pattern is performed, the impedance measuring circuit board B is used.
Then, the discarded substrate portion 16 is removed, and four circuit boards are commercialized.

[0042]

The present invention will be described below in detail with reference to examples.

Example 1 A circuit board B for impedance measurement shown in FIG. 1 was formed. The circuit pattern A for impedance measurement has a length of the introduction region 2 (length between a and b in FIG. 1) of 300 mm and a circuit width W of the introduction region 2 of 400 mm.
μm, the length of the measurement region 1 (the length between bc in FIG. 1) is 100 mm, and the circuit width w of the measurement region 1 is 100 μm.
And The thickness of the impedance measurement circuit pattern A and the thickness of the reference ground circuit pattern 10 are 18 μm.
m. The (characteristic) impedance of the introduction region 2 was about 46Ω.

Example 2 A circuit board B for impedance measurement shown in FIG. 2 was formed. The circuit pattern A for impedance measurement has a length of the introduction region 2 (length between a and b in FIG. 2) of 100 mm and a circuit width W of the introduction region 2 of 400 mm.
μm, the length of the first measurement region 1a (length between bc in FIG. 2) is 100 mm, the circuit width w of the first measurement region 1a is 100 μm, and the length of the connection region 3 (cd in FIG. 2). 100 mm), and the circuit width H of the connection region 3 is 300 mm.
μm, the length of the second measurement region 1b (the length between d and e in FIG. 2) was 100 mm, and the circuit width w of the second measurement region 1b was 100 μm. The thickness of the impedance measurement circuit pattern A and the thickness of the reference ground circuit pattern 10 were 18 μm. The (characteristic) impedance of the introduction region 2 was about 46Ω, and the (characteristic) impedance of the connection region 3 was about 55Ω.

Comparative Example A circuit board B for impedance measurement shown in FIG. 7 was formed. The circuit pattern A for impedance measurement has a length of the introduction region 2 (length between a and b in FIG. 7) of 300 mm, a length of the measurement region 1 (length between bc in FIG. 1) of 100 mm, The circuit width w of the measurement region 1 and the introduction region 2 was set to 100 μm. The thickness of the impedance measurement circuit pattern A and the thickness of the reference ground circuit pattern 10 were 18 μm.

The impedance measurement circuit patterns A of Examples 1 and 2 and Comparative Example were subjected to impedance measurement by the TDR method to obtain measured waveforms. FIG. 4 shows the measured waveform of the first embodiment, and FIG. 5 shows the measured waveform of the second embodiment.
FIG. 6 shows measured waveforms of the comparative example. FIG.
(A), FIG. 5 (a), and FIG. 6 (a) show measurement waveforms obtained by a normal measurement method. That is, a probe connected to an impedance measuring device is brought into contact with the terminal portion 4 of the introduction region 2, an input signal is input to the measurement region 1 through the introduction region 2, and a reflected signal thereof is obtained as a measurement waveform. That is, the input direction of the input signal is as shown in FIG.
7A, the direction shown by the arrow A in FIG.

On the other hand, FIGS. 4 (b), 5 (b), 6
(B) is a measurement waveform obtained by inputting an input signal, contrary to a normal measurement method. That is, the probe connected to the impedance measuring device is brought into contact with the end of the measurement area 1 (the end of the second measurement area 1b in the second embodiment), and the input signal is directly input to the measurement area 1 and the reflected signal is input. Is obtained as a measurement waveform. That is, the input direction of the input signal is the direction indicated by the arrow B in FIGS. 1 (a), 2 (a) and 7 (a).

As can be seen by comparing FIGS. 4A and 4B, the impedance at the 50% position S of the measurement area 1 (the center of the measurement area 1) is 56.times. In FIG. 5
Ω and 57.0 Ω in FIG. 4B, and the difference between the two is 0.9.
%. As can be seen by comparing FIGS. 5A and 5B, the impedance at the 50% position S1 of the first measurement region 1a (the center of the first measurement region 1a) is as shown in FIG.
(A) is 56.0Ω, and FIG. 5 (b) is 56.5Ω,
The difference between the two is 0.9%, which is 50% of the second measurement area 1b.
The impedance at the position S2 (the center of the second measurement area 1b) is 55.0Ω in FIG. 5A and 5 in FIG. 5B.
4.6Ω, and the difference between the two is 0.7%.

As described above, in the first and second embodiments, between the case where the input signal is directly input to the measurement area 1 and the case where the input signal is input to the measurement area 1 through the introduction area 2 and the connection area 3, There is almost no difference in the impedance measured in the measurement region 1, and the impedance can be measured while suppressing the difference between them within a practically sufficient error of 1% or less. Therefore, the impedance in the measurement region 1 can be measured with little influence of the DC resistance component of the introduction region 2 and the connection region 3, and the impedance measurement in the measurement region 1 can be performed with high accuracy. It is.

On the other hand, as can be seen by comparing FIG. 7A and FIG. 7B, the impedance at the 50% position S of the measurement region 1 (the center of the measurement region 1) is shown in FIG. 6
0.9Ω and 56.7Ω in FIG. 7B, and the difference between the two is 7.5%. As described above, in the conventional device shown in the comparative example, the impedance in the measurement region 1 is measured by being greatly influenced by the DC resistance component in the introduction region 2.
The impedance measurement of the measurement area 1 cannot be performed with high accuracy.

[0051]

As described above, according to the first aspect of the present invention, there is provided an impedance measuring circuit pattern having a measuring region where the impedance is measured, wherein the circuit width of the region other than the measuring region is set to the circuit width of the measuring region. Since it is formed larger than the width, the circuit width in the region other than the measurement region can be increased to reduce the DC resistance component in the region other than the measurement region.
This makes it possible to accurately measure the impedance of the measurement region while suppressing the rise of the measurement waveform obtained by the DR method, and as a result, it is possible to accurately perform the inspection of the signal circuit pattern. Further, even when a plurality of measurement regions are electrically connected, it is possible to suppress the floating of the measurement waveform obtained by the TDR method and accurately measure the impedance of the measurement region. Inspection of the signal circuit pattern can be performed accurately and simultaneously.

According to the invention of claim 2 of the present invention, the circuit width of the region between the terminal portion formed in the region other than the measurement region and the measurement region is formed larger than the circuit width of the measurement region. The circuit resistance of the region other than the measurement region can be reduced by increasing the circuit width of the region other than the region, and T
This makes it possible to accurately measure the impedance of the measurement region while suppressing the rise of the measurement waveform obtained by the DR method, and as a result, it is possible to accurately perform the inspection of the signal circuit pattern. Further, even when a plurality of measurement regions are electrically connected, it is possible to suppress the floating of the measurement waveform obtained by the TDR method and accurately measure the impedance of the measurement region. Inspection of the signal circuit pattern can be performed accurately and simultaneously.

According to the invention of claim 3 of the present invention, the circuit width of all regions other than the measurement region is formed to be larger than the circuit width of the measurement region. The DC resistance component in the region other than the measurement region can be reduced, and the measurement waveform obtained by the TDR method can be prevented from rising, so that the impedance measurement in the measurement region can be performed with high accuracy. Can be performed with high accuracy. Further, even when a plurality of measurement regions are electrically connected, it is possible to suppress the floating of the measurement waveform obtained by the TDR method and accurately measure the impedance of the measurement region. Inspection of the signal circuit pattern can be performed accurately and simultaneously.

According to the invention of claim 4 of the present invention, the impedance of the region other than the measurement region is matched with the reference impedance, so that the reflection of the measurement voltage due to a significant decrease in the impedance value in the region other than the measurement region can be suppressed. This makes it possible to more accurately measure the impedance of the measurement area, and as a result, it is possible to accurately inspect the signal circuit pattern.

According to the invention of claim 5 of the present invention, since the impedance of the terminal portion is used as the reference impedance, reflection of the measurement voltage due to a remarkable decrease in the impedance value in the region other than the measurement region can be suppressed, and the terminal portion can be prevented from being reflected. The reflection of the measurement voltage can be suppressed, and the impedance of the measurement region can be measured more accurately. As a result, the inspection of the signal circuit pattern can be performed more accurately.

According to the invention of claim 6 of the present invention, since the impedance of the measurement area is used as the reference impedance, reflection of the measurement voltage due to a remarkable decrease in the impedance value in the area other than the measurement area can be suppressed, and more accurate. The impedance measurement of the measurement area can be performed, and as a result, the inspection of the signal circuit pattern can be accurately performed.

Further, the invention of claim 7 of the present invention is directed to claim 1
A circuit board for impedance measurement provided with the circuit pattern for impedance measurement according to any one of claims 1 to 6,
Since at least one of the upper and lower conductors in the region other than the measurement region is entirely or partially removed, impedance matching can be relatively easily performed in the region other than the measurement region, and the measurement region with high accuracy can be obtained. The impedance can be easily measured, and as a result, the inspection of the signal circuit pattern can be easily and accurately performed.

The invention of claim 8 of the present invention provides the method of claim 1
A circuit board for impedance measurement provided with the circuit pattern for impedance measurement according to any one of claims 1 to 6,
Since the insulating layer adjacent to the region other than the measurement region is formed of a resin having a lower dielectric constant than the insulating layer adjacent to the measurement region, impedance matching can be relatively easily achieved in the region other than the measurement region, and accuracy can be improved. It is possible to easily perform impedance measurement in a good measurement area, and as a result, it is possible to easily and accurately inspect a signal circuit pattern.

[Brief description of the drawings]

1A and 1B show an example of an embodiment of the present invention, in which FIG. 1A is a plan view, FIG. 1B is a cross-sectional view in an introduction region, and FIG. 1C is a cross-sectional view in a measurement region.

FIGS. 2A and 2B show an example of another embodiment of the present invention, in which FIG. 2A is a plan view, FIG. 2B is a sectional view in an introduction region and a connection region, and FIG.

FIG. 3 is a plan view showing an example of another embodiment of the present invention.

FIGS. 4 (a) and 4 (b) are photographs showing measurement waveforms obtained by impedance measurement by the TDR method of Example 1 of the above.

5 (a) and 5 (b) are photographs showing measurement waveforms obtained by impedance measurement by the TDR method of Example 2 of the above.

FIGS. 6 (a) and 6 (b) are photographs showing measurement waveforms obtained by impedance measurement by the TDR method of the comparative example.

7A and 7B show a conventional example, wherein FIG. 7A is a plan view and FIG. 7B is a cross-sectional view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measurement area 2 Introduction area 3 Connection area 4 Terminal part 5 Conductor 6 Insulating layer A Circuit pattern for impedance measurement B Circuit board for impedance measurement

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yukio Matsushita 1048 Kadoma, Kazuma, Osaka Prefecture F-term in Matsushita Electric Works Co., Ltd. 2G014 AA03 AB01 AB59 AC10 2G028 AA01 BB10 BC01 BE10 CG08 HN09 2G132 AC03 AD03 AD15 AF01 AL11 AL12

Claims (8)

[Claims] 1. An impedance measurement circuit pattern having a measurement area where impedance is measured, wherein the circuit width of an area other than the measurement area is formed to be larger than the circuit width of the measurement area. Circuit pattern for measurement. 2. The circuit according to claim 1, wherein the circuit width of the region between the terminal portion formed in the region other than the measurement region and the measurement region is larger than the circuit width of the measurement region. Circuit pattern for impedance measurement. 3. The impedance measurement circuit pattern according to claim 1, wherein the circuit width of all regions other than the measurement region is formed larger than the circuit width of the measurement region. 4. The circuit pattern for impedance measurement according to claim 1, wherein the impedance in a region other than the measurement region is matched with a reference impedance. 5. The impedance measuring circuit pattern according to claim 4, wherein the impedance of the terminal portion is used as a reference impedance. 6. The circuit pattern for impedance measurement according to claim 4, wherein the impedance of the measurement area is used as a reference impedance. 7. An impedance measurement circuit board provided with the impedance measurement circuit pattern according to claim 1, wherein at least one of an upper layer and a lower layer of a region other than a measurement region is provided. A circuit board for impedance measurement, wherein the circuit board is entirely or partially removed. 8. An impedance measuring circuit board provided with the impedance measuring circuit pattern according to claim 1, wherein an insulating layer adjacent to a region other than the measuring region is an insulating layer adjacent to the measuring region. A circuit board for impedance measurement, comprising a resin having a lower dielectric constant than a layer.