JP4810756B2 - Printed wiring board - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a printed wiring board, and more particularly to measurement of characteristic impedance.
[0002]
[Prior art]
In order to maintain the quality of the printed wiring board, it is necessary to measure the characteristic impedance of the conductor circuit. Conventionally, as shown in FIG. 6, the characteristic impedance of a conductor circuit is measured by transmitting and receiving an electrical signal by bringing a probe 92 connected to an impedance measuring machine 91 into contact with an impedance measurement region 94 of a printed wiring board 93. It had been. In the impedance measurement region 94, a measurement circuit 95 and a ground circuit 96 are provided. The measurement circuit 95 is connected to the measurement terminal 951, and the ground circuit 96 is connected to the ground terminal 961.
The probe 92 has a measurement pin 925 and a ground pin 926, and is brought into contact with the measurement terminal 951 and the ground terminal 961 of the printed wiring board 93, respectively. Then, a signal current composed of a pulse current of a predetermined voltage is transmitted from the impedance measuring device 91 to the measuring circuit 95. Then, a reflected current flows from the measurement circuit 95 toward the impedance measuring device 91. The characteristic impedance of the conductor circuit of the printed wiring board is calculated and displayed based on the incident voltage and the reflected voltage. Reference numeral 97 denotes a cable.
[0003]
In recent years, with the increase in processing speed of computers and the like, demands on the performance of printed wiring boards through which signals flow have become stricter. Therefore, there is a demand for accurately grasping the characteristic impedance that can occur in the printed wiring board.
[0004]
[Problems to be solved]
However, in the conventional impedance measurement region 94, since the measurement circuit 95 is a single line, it is only possible to measure the maximum value of the characteristic impedance that can occur in the conductor circuit in the printed wiring board.
Actually, there are variations in characteristic impedance that can occur in a conductor circuit. For this reason, if only the upper limit of the characteristic impedance is measured, the characteristics of the conductor circuit cannot be accurately grasped.
[0005]
In view of the conventional problems, the present invention intends to provide a printed wiring board having an impedance measurement region capable of accurately grasping the characteristics of a conductor circuit.
[0006]
[Means for solving problems]
The present invention is a printed wiring board having a product area having a conductor circuit to be a product and an impedance measurement area for measuring characteristic impedance,
The impedance measurement region includes an upper limit value measuring circuit for measuring an upper limit value of the characteristic impedance that can be generated in the conductor circuit, and a lower limit value measuring circuit for measuring the lower limit value of the characteristic impedance that can be generated in the conductor circuit. Do Ri,
The upper limit measurement circuit is a single wire,
On the other hand, auxiliary circuits are arranged along the longitudinal direction on both sides of the lower limit measurement circuit.
The line widths of the upper limit value measuring circuit, the lower limit value measuring circuit and the auxiliary circuit are the same as or different from the line width of the conductor circuit within ± 10%.
The printed circuit board is characterized in that the wiring pitch between the lower limit value measuring circuit and the auxiliary circuit is the same as or different from the wiring pitch of the conductor circuit within ± 2%. ).
[0007]
In the printed wiring board of the present invention, not only the maximum value of characteristic impedance that can be generated in the conductor circuit in the product area but also the minimum value can be measured. For this reason, it is possible to accurately grasp the characteristics of the conductor circuit.
As described above, according to the present invention, it is possible to provide a printed wiring board having an impedance measurement region capable of accurately grasping the characteristics of a conductor circuit.
[0008]
In the present invention, a power supply circuit or a ground circuit may be disposed above or / and below the upper limit value measuring circuit and the lower limit value measuring circuit via an insulating layer. The upper limit value measurement circuit and the lower limit value measurement circuit may be formed on the surface of the printed wiring board, or may be formed inside.
[0009]
In the present invention, the upper limit value measuring circuit is a single wire, and auxiliary circuits are arranged along the longitudinal direction on both sides of the lower limit value measuring circuit, and the upper limit value measuring circuit is provided. The line widths of the circuit, the lower limit measurement circuit, and the auxiliary circuit are the same as or different from the line width of the conductor circuit, and the lower limit measurement circuit and the auxiliary circuit wiring pitch is the same or the difference between the wiring pitch of the conductive circuits Ru der within 2% ±.
Hereinafter, this point will be described in more detail.
[0010]
Upper limit measuring circuit described above, is substantially a single line of the same line width as that of the conductors circuit, it is possible to measure the maximum value of the characteristic impedance which may occur in the conductor circuit.
The lower limit measurement circuit has a plurality of auxiliary circuits arranged in parallel. This structure is a model of the structure of a part that is considered to exhibit the minimum value of characteristic impedance that can be generated in a conductor circuit in the product area. Therefore, according to this lower limit value measuring circuit, it is possible to measure the minimum value of characteristic impedance that can occur in the conductor circuit.
[0011]
For example, there is at least one conductor circuit next to the part to be measured in the conductor circuit, and the gap between the two circuits may be considered to be the minimum characteristic impedance that can occur in the conductor circuit in the product area. It is a narrow part.
Here, the auxiliary circuit is a model of a circuit arranged next to the conductor circuit. At least one auxiliary circuit is arranged on both sides of the lower limit value measuring circuit.
The wiring pitch between the lower limit value measuring circuit and the auxiliary circuit is the distance between the central portions of both circuits.
[0012]
On the other hand, when the difference between the line width of the upper limit measurement circuit, the lower limit measurement circuit and the auxiliary circuit and the line width of the conductor circuit exceeds ± 10%, or the wiring pitch between the lower limit measurement circuit and the auxiliary circuit If the difference between the wiring pitch of the conductor circuit exceeds ± 2%, the upper limit value and lower limit value of the characteristic impedance of the conductor circuit may not be measured.
[0013]
In the present invention, the upper limit value measuring circuit, the lower limit line width of the measuring circuit and the auxiliary circuit, Ru same or der is within 10% the difference between the line width of the stbm want to know the characteristic impedance at the conductor circuit .
Thereby, the upper limit value and lower limit value of the characteristic impedance of the measurement target part can be measured.
If there are two parts to be measured in the product area where you want to know the characteristic impedance, for example, the upper limit value measurement circuit, lower limit value measurement circuit, and auxiliary circuit are added to the line width of the measurement target part with a narrow line width. The line width is often matched as described above. This is because the characteristic impedance of the measurement target part having a large line width is considered to fall within the range of the upper limit value and the lower limit value of the characteristic impedance of the measurement target part having a narrow line width.
[0014]
Further, in the present invention, the wiring pitch of the lower limit value measuring circuit and auxiliary circuit are identical or the difference between the wiring pitch of stbm want to know the characteristic impedance in conductive circuits Ru der within 2% ±.
Thereby, the upper limit value and the lower limit value of the characteristic impedance of the measurement target part can be measured.
When there are conductor circuits with different wiring pitches in the product area, for example, the wiring pitch between the lower limit value measuring circuit and the auxiliary circuit is often adjusted to the narrower wiring pitch as described above. This is because the lower limit value of the characteristic impedance of the part to be measured with the wider wiring pitch is considered to be larger than the lower limit value of the characteristic impedance of the part to be measured with the narrower wiring pitch.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The ratio (L1 / L2) between the length L1 of the upper limit value measuring circuit and / or the lower limit value measuring circuit and the length L2 of the product region is preferably 0.5 to 1 ( Claim 2 ). This stabilizes the measured value of the characteristic impedance. If L1 / L2 is less than 0.5, the measured value may be inaccurate. In addition, the measurement of characteristic impedance is often performed after the product area is separated into a certain amount. For this reason, even if the L1 / L2 is longer than 1, it becomes meaningless because it is cut by the amount exceeding 1 at the time of singulation.
[0016]
The impedance measurement region is preferably arranged outside the product region (claim 3 ). If the impedance measurement area is formed outside the product area, it is cut off during the outer shape processing of the product area and does not remain in the product. Therefore, miniaturization of the product can be prevented.
[0017]
The impedance measuring region is preferably arranged in the product area (claim 4). As a result, the characteristic impedance can be measured for each product area, so that a more accurate measurement value can be obtained.
[0018]
【Example】
Embodiments of the present invention will be described in more detail using examples.
(Example 1)
As shown in FIG. 1, the printed wiring board 8 of this example includes a product region 7 having a conductor circuit 71 and an impedance measurement region 6.
The impedance measurement area 6 includes an upper limit measurement circuit 1 that measures the upper limit value of the characteristic impedance that can be generated in the conductor circuit 71 in the product area 7, and a lower limit that measures the lower limit value of the characteristic impedance that can be generated in the conductor circuit 71. And a value measuring circuit 2.
[0019]
The line widths B ₂ and B ₃ , the wiring pitches P ₂₃ and P ₃₃ , and the gap widths B ₂₃ and B ₃₃ of the lower limit measurement circuit 2 and the auxiliary circuit 3 are the line width B ₇₁₁ and the wiring pitch P in the conductor circuit 71. ₇₁ and the gap width B ₇₀ are matched with the narrow wiring portion 711, for example, in the vicinity of the bonding pad. Specifically, the line width B ₂ of the lower limit value measuring circuit 2 is 100 μm, which is the same as the line width B ₇₁₁ of the wiring portion 711 of the conductor circuit 71. Two auxiliary circuits 3 are arranged on both sides of the lower limit value measuring circuit 2 along the longitudinal direction with a gap width B ₂₃ equal to the gap width B ₇₀ of the wiring portion 711 of the conductor circuit 71. . The gap width B ₃₃ between the auxiliary circuits 3 is also 100 μm, which is the same as the gap width B ₇₀ of the wiring part 711 of the conductor circuit 71. Line width _{B 3} of the auxiliary circuit 3 is 100 [mu] m, the same as the line width _{B 711} of the wiring portion 711 of the conductor circuit 71.
The wiring pitch P ₂₃ between the lower limit measurement circuit 2 and the auxiliary circuit 3 and the wiring pitch P ₃₃ between the auxiliary circuits 3 are the same as the wiring pitch P ₇₀ of the wiring portion 711 of the conductor circuit 71.
Upper limit measuring circuit 1 is a single line having the same line width _{B 1} and the line width _{B 711} of the wiring portion 711 of the conductor circuit 71. Its line width B ₁ is 100 μm.
[0020]
An upper limit measurement terminal 11 and a lower limit measurement terminal 21 are connected to one end of the upper limit measurement circuit 1 and the lower limit measurement circuit 2.
As shown in FIGS. 2 and 3, a solid power supply circuit 4 is arranged inside the impedance measurement region 6. The power supply circuit 4 has a shape approximately approximate to the same position as the power supply circuit in the product area. The internal power supply circuit 4 is connected to an external power supply terminal 43 through a via hole 42 having a diameter of 0.3 mm formed in the impedance measurement region 6. As shown in FIG. 3, an insulating layer 85 made of glass epoxy resin and having a thickness of 75 μm is interposed between the power supply circuit 4 and the upper limit value measuring circuit 1 and the lower limit value measuring circuit 2. The upper limit value measuring circuit 1, the lower limit value measuring circuit 2, the auxiliary circuit 3 and the power supply circuit 4 are each plate-shaped and have a microstrip line structure with their plate surfaces facing each other in parallel.
[0021]
As shown in FIG. 1, the length L1 of the upper limit value measuring circuit 1 and the lower limit value measuring circuit 2 is 40 mm, the length L2 of the product region 7 is 42.5 mm, and the ratio between them (L1 / L2 ) Is 0.94.
The conductor circuit 71 provided in the product region 7 has a wiring portion 711, a bonding pad 712, and a via hole 710. In the center of the product area 7, a mounting portion 72 for mounting electronic components is provided.
[0022]
As shown in FIG. 4, the impedance measurement region 6 is formed outside the product region 7. The impedance measurement region 6 is formed at a gripping margin 81 at the peripheral edge of the printed wiring board 8 and is located 20 mm inside from the edge of the substrate. The impedance measurement region 6 is arranged so as to be the same as the extension line of the outer shape of the product region 7.
[0023]
As shown in FIG. 1, when measuring the characteristic impedance in the impedance measurement region 6, the measurement pin 525 and the power supply pin 526 connected to the impedance measuring machine 51 are connected to the upper limit value measurement terminal 11 and the impedance measurement region 6, respectively. Contact the power supply terminal 43. The characteristic impedance at this time was 53Ω.
Next, the measurement pin 525 and the power supply pin 526 are brought into contact with the lower limit value measurement terminal 12 and the power supply terminal 43, respectively. The characteristic impedance at this time was 48Ω.
The impedance measurement region 6 is cut and removed as a part of the gripping margin 81 by external processing after characteristic impedance measurement.
[0024]
In the printed wiring board 8 of this example, not only the maximum value of the characteristic impedance that can be generated in the conductor circuit but also the minimum value can be measured. For this reason, it is possible to accurately grasp the characteristics of the conductor circuit.
[0025]
(Example 2)
In this example, as shown in FIG. 5, the impedance measurement region 6 is arranged inside the product region 7. The product region 6 is separated into individual products by the outer shape processing of the printed wiring board 8, and the impedance measurement region 6 remains in the product.
The impedance measurement region 6 is formed for each product region 7. Therefore, it is possible to measure an accurate characteristic impedance for each product area.
Others are the same as in the first embodiment. In this example, the same effect as in the first embodiment can be exhibited.
[Brief description of the drawings]
FIG. 1 is a plan view of a printed wiring board according to Embodiment 1. FIG.
2 is a plan view of a power supply circuit formed inside a printed wiring board in Embodiment 1. FIG.
3 is a cross-sectional view of a printed wiring board in Embodiment 1. FIG.
FIG. 4 is an explanatory diagram of an arrangement of impedance measurement regions in the first embodiment.
FIG. 5 is an explanatory diagram of an arrangement of impedance measurement regions in the second embodiment.
FIG. 6 is an explanatory diagram of a conventional impedance measurement method.
[Explanation of symbols]
1. . . Upper limit measurement circuit,
11. . . Terminal for measuring the upper limit value,
2. . . Lower limit measurement circuit,
21. . . Lower limit measurement terminal,
3. . . Auxiliary circuit,
4). . . Power supply circuit,
42. . . Beer hall,
43. . . Power terminal,
51. . . Impedance measuring machine,
6). . . Impedance measurement area,
7). . . Product areas,
71. . . Conductor circuit,
711. . . Wiring section,
8). . . Printed wiring board,

Claims (4)

A printed wiring board having a product area to be a product having a conductor circuit and an impedance measurement area for measuring characteristic impedance,
The impedance measurement region includes an upper limit value measuring circuit for measuring an upper limit value of the characteristic impedance that can be generated in the conductor circuit, and a lower limit value measuring circuit for measuring the lower limit value of the characteristic impedance that can be generated in the conductor circuit. Do Ri,
The upper limit measurement circuit is a single wire,
On the other hand, auxiliary circuits are arranged along the longitudinal direction on both sides of the lower limit measurement circuit.
The line widths of the upper limit value measuring circuit, the lower limit value measuring circuit and the auxiliary circuit are the same as or different from the line width of the conductor circuit within ± 10%.
The printed wiring board is characterized in that a wiring pitch between the lower limit measuring circuit and the auxiliary circuit is the same as or different from a wiring pitch of the conductor circuit within ± 2% . The ratio (L1 / L2) between the length L1 of the upper limit value measuring circuit and / or the lower limit value measuring circuit and the length L2 of the product area is 0.5 to 1. printed circuit board, characterized in that. 3. The printed wiring board according to claim 1, wherein the impedance measurement area is disposed outside the product area . The printed wiring board according to claim 1, wherein the impedance measurement area is disposed in the product area .

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