JPH05102622A - Printed wiring board and inspection apparatus therefor - Google Patents

Abstract

PURPOSE:To provide a printed wiring board which can easily undergo the measurement of characteristic impedance and an inspection apparatus for easily deciding pass/fail of the printed wiring board. CONSTITUTION:A printed wiring board provides independent patterns 2, 6 in the same width as a signal pattern on a signal layer, signal layer connecting through holes 3, 7 at the end point of the independent patterns and also provides therein through holes 4, 5 connected to GND layer and power supply layer. An inspection apparatus comprises probe pins 8 corresponding to through holes of this printed wiring board, a characteristic impedance measuring means 10, a characteristic impedance setting means 11 for setting a target value, a comparison means 12 for deciding pass/fail by comparing measured data of the characteristic impedance measuring means with the target value and a display means 13 for displaying the decision results. Therefore, impedance measurement can be realized easily to decide pass/fail without complicated waveform measurement and computation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board and an inspection device for determining the quality of the printed wiring board by measuring its characteristic impedance.

[0002]

2. Description of the Related Art In recent years, due to the progress of device technology, the switching speed has been increased, and the mismatch between the input / output impedance of the device and the characteristic impedance of the printed wiring board on which it is mounted leads to an increase in the delay time. It is becoming an obstacle to device performance. Therefore, conventionally, the signal pattern width of the printed wiring board and the power supply GND and the signal interlayer thickness are adjusted to match the characteristic impedance of the device and the printed wiring board. As a result, a printed wiring board having poor performance may be mixed.

[0003]

In order to prevent the above-described defective printed wiring board from being mixed in, it is sufficient to measure the characteristic impedance of each sheet to determine whether the printed wiring board is good or bad. To determine the electrical characteristics of the board, select a pattern with a long wiring length from the signal pattern used for logical connection, and calculate the characteristic impedance of the signal pattern by measuring the reflected wave using a cable or the like with a known characteristic impedance. Since it was decided based on this, there was a problem that the inspection took a long time and could not withstand actual operation. For this reason, the characteristic impedance of the printed wiring board is often not measured, and there is a problem in that the performance and reliability of the device are deteriorated due to mixing of a defective printed wiring board.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a printed wiring board whose characteristic impedance can be easily measured, and an inspection apparatus which can easily determine the quality of the printed wiring board.

[0005]

In order to achieve the above object, a printed wiring board of the present invention is a printed wiring board in which a signal layer having a signal pattern, a GND layer and a power supply layer are laminated. An independent pattern having the same width as the signal pattern is formed, a signal layer connecting through hole is provided at an end point of the independent pattern, and through holes connected to the GND layer and the power supply layer are provided near the signal layer connecting through hole, respectively. It has a different configuration. In order to achieve the above-mentioned object, the inspection device of the present invention forms an independent pattern having the same width as the signal pattern on the signal layer, provides signal layer connection through holes at the end points of the independent pattern, and connects the signal layer. A plurality of probe pins corresponding to the through holes of the printed wiring board, each having a through hole connected to the GND layer and a power supply layer in the vicinity of the through hole, and a characteristic impedance measuring unit for calculating a characteristic impedance,
A characteristic impedance setting unit that sets the upper and lower limits of the target value of the characteristic impedance, a comparison unit that compares the measurement data of the characteristic impedance measurement unit with the target value of the characteristic impedance setting unit, and determines whether the quality is good or bad, and the comparison unit. And a display unit that displays the determination result of.

[0006]

When the impedance of the printed wiring board is measured, it is not necessary to select a pattern having a long wiring length from the signal pattern used for the logical connection, and the signal layer connection through hole and the GND or power supply connection through hole of the independent pattern are formed. It should be selected as the measurement point. In the inspection device, the comparison unit compares the measurement data from the characteristic impedance measurement unit with a target value set in the characteristic impedance measurement unit to determine the quality of the printed wiring board, and displays the result on the display unit.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a printed wiring board according to an embodiment of the present invention. On the surface signal layer of the present printed wiring board 1, the surface signal layer independent pattern 2 is wired, and the surface signal layer connection through hole 3 is provided at the end point thereof. In the vicinity of the surface signal layer connecting through hole 3, a GND connecting through hole 4a to which GND is supplied and a power connecting through hole 5a to which power is supplied are provided. Similarly, the back signal layer of the printed wiring board 1 is provided with the back signal layer independent pattern 6, the back signal layer connection through hole 7, the GND connection through hole 4b, and the power supply connection through hole 5b.

When measuring the characteristic impedance of each signal layer in the printed wiring board 1 configured as described above, the front and back signal layer connection through holes 3, the back signal layer connection through holes 7, and the GND connection are used. Through hole 4
It suffices to select a, 4b and the power supply connection through holes 5a, 5b as the measurement points, which saves the trouble of selecting a pattern having a long wiring length from the signal pattern used for logical connection, and can be easily selected.

FIG. 2 is a block diagram showing the arrangement of an inspection apparatus according to an embodiment of the present invention. The inspection apparatus includes a characteristic impedance measuring unit 10, a characteristic impedance setting unit 11,
It is composed of a comparison unit 12 and a display unit 13. The characteristic impedance measuring unit 10 has six probe pins 8 corresponding to each through hole of the printed wiring board 1 shown in FIG.
Are respectively connected by cables 9. The probe pin 8 is connected to the front signal layer connecting through hole 3 of the printed wiring board 1, the back signal layer connecting through hole 7, the GND connecting through holes 4a and 4b, and the power connecting through hole 5a,
The test is performed by plugging in 5b.

The characteristic impedance can be calculated by measuring and calculating the capacitance and the inductance with respect to the GND or the power supply layer facing the signal layer to be measured of the printed wiring board 1. However, the characteristic impedance of the signal layer, the GND, and the power supply layer can be calculated. The smaller the interlayer distance, the lower the characteristic impedance. Therefore, the characteristic impedance measuring unit 10 measures the capacitance and inductance between the signal layer under measurement and the GND layer and between the signal layer under measurement and the power supply layer and calculates the impedance, and selects the lower value as the characteristic impedance of the signal layer under measurement. In addition to the function, it has a measurement signal layer number addition function. Therefore, it is possible to perform measurement even on a printed wiring board that does not know whether the measured signal layer faces the GND layer or the power supply layer.

Further, the target value of the characteristic impedance is set in the characteristic impedance setting section 11 for each signal layer such that the upper and lower limits are in a good range. The comparison unit 12 compares and determines each signal layer data of the characteristic impedance measuring unit 10 and the target value of the characteristic impedance setting unit 11, and the display unit 1
At 3, the results for each signal layer are displayed. As a result, it is possible to easily determine the quality without performing troublesome waveform measurement and calculation. The present invention has been described above with reference to the preferred embodiments, but the present invention is not limited to the above embodiments.

[0012]

As described above, in the printed wiring board of the present invention, the signal layer connection through hole, the GND connection through hole and the power supply connection through hole may be selected as the measurement points, and they are used for the logical connection. This eliminates the need to select a pattern having a long wiring length from the signal pattern, and makes impedance measurement easy. Further, the printed wiring board inspection apparatus of the present invention determines the quality of the printed wiring board by comparing the measurement data from the characteristic impedance measurement unit with the target value set in the characteristic impedance measurement unit by the comparison unit, Since the result is displayed on the display,
It becomes possible to easily judge pass / fail without performing troublesome waveform measurement and calculation.

[Brief description of drawings]

FIG. 1 is a plan view of a printed wiring board according to an exemplary embodiment of the present invention.

FIG. 2 is a configuration block diagram of an inspection apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 1 ... Printed wiring board 2 ... Front signal layer independent pattern 3 ... Front signal layer connection through hole 4a, 4b ... GND connection through hole 5a, 5b ... Power connection through hole 6 ... Back signal layer independent pattern 7 ... Back signal layer connection through Hall 8 ... Probe pin 9 ... Cable 10 ... Characteristic impedance measurement unit 11 ... Characteristic impedance setting unit 12 ... Comparison unit 13 ... Display unit

Claims (2)

[Claims] 1. A signal layer on which a signal pattern is formed and GND.
In a printed wiring board formed by stacking layers and power supply layers, an independent pattern having the same width as a signal pattern is formed on the signal layer, a signal layer connection through hole is provided at an end point of the independent pattern, and the signal layer connection through is formed. GND near the hall
A printed wiring board having through holes connected to the power supply layer and the power supply layer, respectively. 2. A through hole in which an independent pattern having the same width as a signal pattern is formed on a signal layer, a connection through hole is provided at an end point of the independent pattern, and the GND layer and a power supply layer are connected in the vicinity of the connection through hole. A plurality of probe pins corresponding to the respective through holes of the printed wiring board, the characteristic impedance measuring section for calculating the characteristic impedance, the characteristic impedance setting section for setting the upper and lower limits of the target value of the characteristic impedance, and the characteristic impedance A printed wiring comprising: a comparison unit that compares the measurement data of the measurement unit with a target value of the characteristic impedance setting unit to determine pass / fail; and a display unit that displays the determination result of the comparison unit. Board inspection device.