JPH05302955A - Pattern inspection method of printed wiring board - Google Patents

Abstract

PURPOSE:To increase the reliability of the distinction of whether a carbon printing operation is good or not in a printed wiring board wherein prescribed circuit patterns are connected by using a carbon conductor. CONSTITUTION:Through holes 13, 13 are made in two places in a board 1a; lands 11a, 11b, 12a, 12b which are set to a continuity state by means of conductive metal pins 14 inside said through holes are formed on both the surface and the rear. A carbon conductor 15 is printed across the lands 11a, 12a on one face side of the board; probes 7a, 7b are brought into contact with the lands 11b, 12b on the other face side of the board; the resistance value of the carbon conductor 15 is detected via the lands. Even when contact parts of the probes 7a, 7b are different, its measured value is not changed sharply, and a carbon printing operation can be inspected with high reliability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern inspection method for a printed wiring board, and more specifically, it forms a circuit pattern by etching, prints a solder resist on the circuit pattern, and then prints a carbon conductor between predetermined lands. The present invention relates to a pattern inspection method for inspecting the wiring state of the carbon conductor when printing.

[0002]

2. Description of the Related Art First, an outline of a carbon conductor will be described with reference to FIG. To obtain a printed wiring board, for example, a copper-clad laminated substrate 1 is covered with a dry film having a predetermined wiring pattern, exposed to form an etching resist, developed, and then etched to form a circuit pattern 2 made of a copper foil. To form.

Here, for convenience of explanation, of the four formed circuit patterns, the reference numeral is 2 from the left in FIG.
a, 2b, 2c and 2d.

Thereafter, the solder resist 3 is provided on the circuit pattern 2. In this case, the portion where the solder resist 3 is formed is the hatched portion in FIG. 3, and the predetermined land is left exposed on the surface. In this example, the land of the circuit pattern 2a on the left side and the land of the circuit pattern 2d on the right side are exposed, and the circuit patterns 2b and 2d located between them are entirely masked by the solder resist 3. It is assumed that

By the way, in order to connect the circuit patterns 2a and 2d to each other, it suffices to form the connection patterns at the same time during the etching process. However, there is no wiring space on the substrate 1, and there is another space between them. The carbon conductor 4 is used when there are the circuit patterns 2b and 2c.

That is, the connecting carbon conductor 4 is printed on the solder resist 3 so as to jump the circuit patterns 2b and 2c between the land of the circuit pattern 2a and the land of the circuit pattern 2d.

At this time, the inspection pattern 5 for inspecting the pattern shift made of carbon is simultaneously formed on the blank portion 1a of the substrate 1. FIG. 4 shows a cross-sectional view thereof, according to which the inspection pattern 5 is printed between the lands 6a formed in the margin portion 1a in advance.

[0008]

The inspection of the pattern deviation is performed by bringing a pair of probes 7a and 7b into contact with the inspection pattern 5 and measuring the resistance value therebetween.

However, the resistance value of carbon is extremely higher than that of copper, etc., and even if the contact portions of the probes 7a and 7b are slightly changed, the detected resistance values are greatly different, which causes a problem in reliability.

Since carbon printing is difficult due to its peculiarity and often looks defective even if it looks good, inspection of all products is required.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above conventional circumstances, and is characterized in that a predetermined circuit pattern is formed on a copper clad laminated board and the land of the circuit pattern is removed. In a pattern inspection method for a printed wiring board, in which a carbon conductor is printed between predetermined lands after forming a solder resist to conduct those circuit patterns, in the predetermined area of the board, two through holes are formed, and Provided on both front and back sides are inspection lands that are inserted into the same through holes with conductive metal pins whose electrical resistance value is lower than that of carbon, and between the inspection lands at the same time when the carbon conductor is printed. Form a carbon conductor for electrical resistance inspection, measure the resistance value of the inspection carbon conductor from the inspection land on the back side, and check the wiring condition of the carbon conductor. Lies in the fact that so as to 査.

In this case, it is preferable that the through hole and the inspection land are formed in the blank portion of the substrate.

[0013]

[Function] Since the probe is brought into contact with the inspection land and the resistance value of the inspection carbon conductor is detected through the land, the measured value does not change significantly even if the contact portion of the probe is different, and reliability is improved. High-quality inspection can be performed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In these figures,
The same reference numerals are used for the same parts as the conventional example described above.

First, for example, a dry film having a predetermined circuit pattern is attached to the copper clad laminate 1, exposed to form an etching resist, and then etched to form predetermined circuit patterns 2a to 2d.

At the time of forming this circuit pattern, the inspection lands 11a and 11b are provided at two positions on both sides of the blank portion 1a of the substrate 1.
12a and 12b are formed coaxially. And
Through holes 13, 13 are formed in the center of each inspection land.
And a conductive metal pin having a lower electric resistance than carbon, for example, a metal pin 14, 14 made of copper, iron, aluminum, or the like is inserted through the through holes 13, 13.
With these pins, the inspection lands 11a, 11b, 12a
And 12b are made conductive.

Next, a solder resist 3 is formed except for the lands of the circuit pattern 2a and the lands of the circuit pattern 2d, and a carbon conductor 4 for connection is printed between these lands to form the circuit patterns 2a and 2d. Although electrically connected, at the same time, the inspection carbon conductor 15 is also printed between the inspection lands 11a and 12a.

Thereafter, the resistance value of the inspection carbon conductor 15 is measured to inspect whether or not the carbon printing including the wiring state of the connecting carbon conductor 4 is good or bad, that is, the presence or absence of print misalignment. In this case, , Probes 7a, 7b
Is an inspection land 11 on the back side where carbon printing is not performed.
b, 12b.

Since the electric resistance of the lands 11b and 12b is extremely smaller than that of carbon, the probes 7a and 7b
Carbon conductor 15 for inspection even if the contact position of b is displaced
The resistance of the carbon conductor is hardly affected, and the quality of the carbon conductor can be accurately determined.

In the above-mentioned embodiment, the inspection pattern for carbon printing is formed on the blank portion 1a of the substrate 1, but the land in the circuit on which the carbon conductor is printed can be conducted to the back side by the through hole. For example, the resistance value of the carbon conductor may be measured using the land on the back surface side.

[0021]

As described above, according to the present invention,
Through holes are formed at two positions on the board, and lands that are brought into conduction by conductive metal pins in the through holes are formed on both front and back surfaces of the board, and carbon conductors are provided between lands on one surface side of the board. Is printed, the probe is brought into contact with the land on the other surface side of the substrate, and the resistance value of the carbon conductor is detected through the land. It is possible to perform a highly reliable inspection of carbon printing without any change.

[Brief description of drawings]

FIG. 1 is a schematic plan view of the same printed circuit board illustrating an example of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an explanatory view showing a substrate to be inspected by a conventional inspection method.

FIG. 4 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

 1 board 1a board margin 2 circuit pattern 3 solder resist 4 connection carbon conductor 11, 12 inspection land 13 through hole 14 conductive metal pin 15 inspection carbon conductor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05K 3/00 T 6921-4E

Claims (2)

[Claims] 1. A predetermined circuit pattern is formed on a copper-clad laminated substrate, a solder resist is formed except for the land of the circuit pattern, and then a carbon conductor is printed between the predetermined lands to make those circuit patterns conductive. In the method for inspecting a pattern of a printed wiring board, a conductive metal pin having two through holes formed in a predetermined portion of the substrate and having electric resistance values lower than that of carbon inserted through the through holes on both front and back surfaces thereof. To provide a conductive land for inspection, and at the same time when printing the carbon conductor, form a carbon conductor for electrical resistance inspection between the above-mentioned inspection lands, and from the inspection land on the back side of A method for inspecting a pattern of a printed wiring board, which comprises measuring a resistance value and inspecting a wiring state of a carbon conductor. 2. The pattern inspection method for a printed wiring board according to claim 1, wherein the through hole and the inspection land are formed in a blank portion of the substrate.