JPH0573181B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for investigating the connection relationship of an electrical circuit network, which investigates the connection relationship of a circuit network such as a printed circuit board in order to obtain information on the connection relationship of the circuit network. [Prior Art] A device in which a large number of terminal points are provided on an insulating substrate, required terminal points are connected to each other by printed wiring, and a predetermined function is achieved by connecting electrical parts to the terminal points. is known as a printed circuit board. In such a device,
Many identical circuit boards (hereinafter referred to as bare boards) before electrical components are mounted are manufactured, but some of these manufactured bare boards have defects in their circuits. There is a risk of If such a defective bare board is used, the device will not be able to perform its initial functions. For this reason, each manufactured bare board is checked for circuit defects. By the way, in general, when manufacturing a bare board, it is often impossible to use information about circuit connection relationships that exists when designing a circuit network. Therefore, in this case, the circuit connections of the manufactured bare board are unknown. Therefore, we measured the capacitance value (proportional to the area of the conductor connected to that terminal point) at each terminal point of multiple bare boards, and found that the capacitance value at the same terminal point on each bare board was significantly different from the others ( (If a disconnection or short circuit occurs in the conductor, the above area will be different and the capacitance value will be different.) Excluding bare boards,
Select one of the remaining bare boards, check the circuit connections on this bare board,
A method is used in which this connection relationship is stored as information, and this bare board is used as a reference to check other bare boards by comparing this information with the bare board. Hereinafter, an apparatus for finding connection relationship information of a reference bare board and inspecting other bare boards will be explained with reference to FIG. FIG. 4 is a block diagram of an apparatus used in the bare board inspection method. In the figure, 1 is a bare board to be inspected, 2 is a conductive plate, and 3 is a dielectric layer inserted between the bare board 1 and the conductive plate 2. 4 is a terminal hole (terminal point) of the bare board 1, into which a predetermined electrical component is inserted. A large number of terminal points 4 are formed. A conductor 5 forms a circuit of the bare board 1 and electrically connects predetermined terminal points. Reference numerals 6 and 7 are probes of this inspection device, which are inserted into each terminal point 4 arbitrarily. 10 is a positioning device that moves the probe 6 to a predetermined position and inserts it into the terminal point 4 at that position; 11 is a positioning device that similarly moves and inserts the probe 7. 12 is a resistance measuring device that measures the resistance value between the probe 6 and the probe 7; when the terminal points where the respective probes 6 and 7 are in contact are connected by the conductor 5, the resistance value is low; High if not connected. 13 is a capacitance measuring device that measures the capacitance value between the conductive plate 2 and the conductor connected to the probe 6 or the probe 7, and the measured value is the extension of the conductor 5 connected to the terminal point. Approximately proportional to distance. Terminal points whose measured capacitance values are similar may be connected to each other. 14 is a positioning device 10,1
1. A control computer that controls the resistance measuring device 12 and the capacitance measuring device 13. A conventional connection relationship investigation method using this device is as follows. That is, first, measure the capacitance values of all terminal points with probe 6 or probe 7, pick out the terminal points showing the maximum capacitance value and its approximate value, and measure all the combinations of two terminal points for those terminal points. Measure the resistance, check which terminal points are connected, and repeat this procedure. This makes it possible to obtain information on the connection relationship of bare boards that serve as a reference. [Problems to be Solved by the Invention] By the way, in the conventional method described above, it is clear that it takes a lot of time to investigate a bare board in which there are many circuits with a small number of connected terminal points. This will be explained using a diagram. FIG. 5 is a plan view of the bare board. In the figure, 16 is a bare board, 17 is a conductor, and P ₁ to P ₁₂ are terminal points, respectively. An actual bare board has hundreds to tens of thousands of terminal points, but the diagram is shown for ease of explanation.
Twelve terminal points are shown. In the illustrated example, 1
There are six circuits in which two terminal points are connected to one conductor (one circuit to which a plurality of terminal points are connected is called a net). In this case, each terminal point
The capacitance values measured at P ₁ to _{P 12} are approximately equal,
All of these terminal points P ₁ to P ₁₂ need to be investigated. This investigation will be conducted as follows. That is, first,
Measure the resistance between terminal point P ₁ and each of the other terminal points P ₂ to P ₁₂ . As a result, it can be seen that terminal points P ₁ and P ₄ are connected. The number of measurements was 11. Next, similar measurements are made for terminal point _P2 . In this case, the number of measurements is already measured between terminal point _P1 ,
It can be seen that there is no connection between terminal point _P4 , so
9 times. In this way all terminal points P ₁
It takes 36 measurements to investigate the connection relationship of ~ _P12 . By the way, if each net has 10 terminal points, 9 terminal points can be excluded from the measurement target when measuring resistance based on the next terminal point, and the number of measurements in the next measurement will be reduced accordingly. However, if there are many nets with two terminal points as described above, there are few terminal points that can be excluded from the measurement target each time resistance is measured using one terminal point as a reference. No reduction in the number of measurements can be expected, and the measurement time will be extremely long. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for investigating connections in an electric circuit network, which can solve the problems of the prior art described above, reduce the number of resistance measurements, and thereby shorten the time required to investigate connections. It is in. [Means for Solving the Problems] In order to achieve the above object, the present invention measures the capacitance values of all terminal points on the board, and measures the capacitance values of each terminal point showing an approximate capacitance value. Select a terminal point that exists within a predetermined distance from a certain terminal point among those terminal points, measure the resistance between the certain terminal point and the selected terminal point, and measure the resistance for each terminal point in turn. It is characterized by doing. [Operation] First, measure the capacitance value of each terminal point on the bare board, then create a set of terminal points with similar capacitance values, pick one terminal point from this set, and Select terminal points within a certain distance from one terminal point. Next, resistance measurement is performed between the one terminal point and each selected terminal point. This method is performed for each terminal point in the set in turn. However, resistance measurements are not performed between terminal points whose connection relationship is known from previous resistance measurements. Such a method significantly reduces the number of resistance measurements. [Example] The present invention will be described below based on the illustrated example. FIG. 1 is a plan view of a bare board for explaining a connection relationship investigation method according to an embodiment of the present invention. In the figure, the same bare board as shown in FIG. 5 is shown. C ₁ indicates a virtual area surrounded by a circle having a radius l and having the terminal point P ₁ as its center. Similarly, C ₂ , C ₃ ,
...C ₁₁ and C ₁₂ are also terminal points P ₂ , P ₃ , ... respectively.
A virtual area surrounded by a circle with radius l centered on P ₁₁ and P ₁₂ is shown. In this embodiment, first, each terminal point P ₁ to P ₁₂
The capacitance value of is measured using the apparatus shown in FIG. These resistances should exhibit almost the same value, and therefore, it is determined that there is a possibility that these terminal points P ₁ to _{P 12} are on the same net. Therefore,
In the next step, the connection relationship between the terminal points _P1 to _P12 is investigated by measuring the resistance using the apparatus shown in FIG. This investigation method will be explained below. First, the terminal point P ₁ is specified and the area C ₁ is defined.
Then, terminal points existing within this area _C1 are selected. The selected terminal points are terminal points P ₂ and P ₄ . Since the position of each terminal point is stored as a coordinate value, the terminal points P ₂ and P ₄ in the area C ₁ are immediately calculated by the control computer 14 shown in FIG. 4.
Next, resistance measurements are performed between terminal points P ₁ and _{P 2} and between terminal points P ₁ and _{P 4} . When the above-described resistance measurement for terminal point P ₁ is completed, terminal point P ₂ is specified, its area C ₂ is determined, and terminal points P ₁ , P ₃ , and P ₅ within that range are selected. Then, resistance measurement is performed between the terminal point _P2 and the selected terminal point. In this case, terminal point P ₂
Since the resistance measurement between −P ₁ has already been performed,
Only resistance measurements are made between terminal points P ₂ - P ₃ and between terminal points P ₂ - _{P 5} . In this way, if the terminal points P ₁ to _{P 12} are sequentially identified and the resistances of the identified terminal points and the terminal points within the area of the identified terminal points are measured, the result will be as shown in the table on the next page.

【table】

〔Effect of the invention〕

As described above, in the present invention, for each terminal point whose capacitance values are similar, each terminal point is designated as a specific terminal point in order, and the terminal points that exist within a predetermined distance from the specific terminal point are Since the resistance is measured between the terminal point and the terminal point, the number of resistance measurements can be significantly reduced, and the time required to investigate connection relationships can be significantly shortened.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a bare board for explaining the connection relationship investigation method according to the embodiment of the present invention, FIGS. 2 and 3 are flowcharts for explaining the procedure of the connection relationship investigation method of the present invention, and FIG. 4 is a FIG. 5 is a block diagram of a device used to investigate connection relationships of bare boards, and FIG. 5 is a plan view of the bare board. 16...Bare board, P ₁ to P ₁₂ ...Terminal point, C ₁
~ _{C 12} ... area.

Claims (1)

[Claims] 1. In an electrical circuit network that has a large number of terminal points connecting electrical elements on a board and circuits that connect required ones of these terminal points, the electrostatic charge between all the terminal points and the conductive plate Electricity characterized by measuring a capacitance value, and sequentially measuring the resistance between each terminal point whose capacitance value is similar to a terminal point existing within a predetermined distance from that terminal point. A method for investigating connections in circuit networks.