JPH0230845Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a flexible printed wiring board provided with a test pattern for testing the conductivity of ink used for printing circuit patterns.

(Prior Art) A flexible printed wiring board (hereinafter abbreviated as FPC) is based on an extremely flexible insulating film such as polyester, on which a desired circuit pattern is printed. This circuit pattern was first formed by printing a pattern using silver ink, and then printing a pattern of the same shape using carbon ink so as to cover the silver ink pattern. Therefore, the conductor resistance of the circuit pattern is largely influenced by the conductivity of the silver ink and carbon ink used for printing.

Furthermore, it is unavoidable that the conductivity of both of these inks varies to some extent each time they are formulated. Therefore, it is inevitable that the conductor resistance of the circuit pattern of the FPC will vary to some extent between production lots. Here, since this circuit pattern connects electronic components to each other, it is necessary to keep the value of the conductor resistance lower than a predetermined value in order to maintain the performance of the electronic device.

Conventionally, the conductor resistance of this circuit pattern was tested by
The contact of a low resistance measuring device was applied to a suitable circuit pattern on the FPC at a predetermined interval, and the resistance was measured between the two points. Therefore, the circuit pattern to be measured must be selected from a part that does not wrap around, and any variation in the spacing between the contacts will directly affect the measured value, and measurement requires skill. . In addition, if the contactor is carelessly applied to the circuit pattern during measurement, it may be damaged, and there is a risk that a good FPC may be turned into a defective product by inspection. It was hot.

(Purpose of the invention) The present invention was made with attention to these points, and it is possible to easily measure conductor resistance even if you are not an expert without having to select the pattern to be measured one by one. The object of the present invention is to provide an FPC with a test pattern that does not cause damage to the pattern.

(Structure of the invention) Therefore, the FPC with inspection pattern according to the invention
In this case, a pattern of a predetermined shape made of silver ink is covered with a pattern of a predetermined shape made of carbon ink as an inspection pattern in an empty space on an insulating film, and a first pattern is formed in which a part of the silver pattern is exposed near the edge. , a second coat of silver ink in a predetermined shape.
The above object is achieved by having a configuration in which a pattern and a third pattern made of carbon ink are printed and arranged, and testing the conductor resistance of the circuit pattern by measuring the conductor resistance of the test pattern. It is.

(Example) Next, an example of implementation of the present invention will be described in detail with reference to the drawings.

The drawing is a plan view of an embodiment of an FPC with a test pattern according to the present invention. In the figure, reference numeral 1 denotes a highly flexible insulating film, such as a plastic film such as polyester, which is often used with a thickness of about 0.2 mm. Reference numeral 2 is a circuit pattern printed on the plastic film 1 by silk printing or the like, in which a predetermined pattern is first printed with silver ink and then printed with carbon ink.

Also, 3 is the first pattern, 4 is the second pattern,
5 is a third pattern, which constitutes a test pattern. The first pattern 3 has lands 32 at both ends of a straight portion 31 having a predetermined length and width.
Similar to the circuit pattern, this pattern is first printed with silver ink, and then printed on top of that with carbon ink. Here, in the land 32, a portion of the pattern formed by the lower layer of silver ink is exposed.

The second pattern 4 consists of a straight line part 41 of a predetermined length and width and lands 42 at both ends thereof, is printed with silver ink, and is equivalent to the lower layer part of the first pattern 3. Further, the third pattern 5 is composed of a linear portion 51 of a predetermined length and width and lands 52 at both ends, and is printed with carbon ink, and is equivalent to the upper layer portion of the first pattern 3. These test patterns are printed all at once using the same ink when printing the circuit pattern 2.

Next, testing of the conductor resistance of a circuit pattern using this test pattern will be described.

First, a contact of a low resistance measuring device is applied to each of the lands 32 of the first pattern 3.
Measure the conductor resistance of Here, if the measured values are within the specifications, the FPC is considered a good product and is transferred to the assembly process. In addition, if it does not meet the specifications, we will identify it as a defective product and measure the conductor resistance of the second and third patterns in the same way as in the previous case to determine if the cause of the defect is in the silver ink. Determine whether the carbon ink is present. Here, this FPC inspection is performed for each
It is effective not only for a 100% check in which all FPCs are inspected, but also for a sampling inspection in which an appropriate number of FPCs are selected from the manufacturing lot and inspected.

Although the illustrated embodiments have been described in detail above, it goes without saying that the present invention is not limited thereto. For example, the linear portions of the first to third patterns may be replaced with curved portions of the same shape, and the shape of the land may include various variations, and the lower layer of the first pattern and the land of the second pattern may be replaced. The shapes do not necessarily have to be the same either. Moreover, the shapes of the first to third patterns do not necessarily have to be the same as long as the standard values of each pattern are properly set.

(Effects of the invention) The present invention is constructed as described above, and the test is simply by applying the contact of the low resistance measuring device to the test pattern, so it is necessary to select the pattern to be used for measurement while taking into account wraparound etc. Therefore, it is easy to keep the distance between the contacts constant. In addition, a part of the silver ink pattern underneath the first pattern is exposed so that it can be clearly distinguished from the third carbon ink pattern, making it easy for even unskilled personnel to inspect the FPC. can be done. In addition, even if the pattern is damaged by contact with the contact during inspection, it will not affect the circuit operation at all because the pattern is only used for inspection. There is no danger of this happening. Furthermore, when a defect is detected, it is easy to know whether the cause of the defect is in the silver ink or the carbon ink, and if this information is fed back to the ink adjustment process when a defect is detected, it is extremely effective for quality control. Become something.

[Brief explanation of the drawing]

The drawing is a plan view of an embodiment of an FPC with a test pattern according to the present invention. 1...Insulating film, 2...Circuit pattern, 3
...First pattern, 4...Second pattern, 5...
3rd pattern, 31, 41, 51...straight line part, 3
2, 42, 52...land.

Claims (1)

[Scope of utility model registration request] In a flexible printed wiring board in which a desired circuit pattern is printed on a highly flexible insulating film using silver ink and carbon ink, a predetermined test pattern is printed using silver ink in the empty space on the insulating film. A first pattern is covered with a pattern of a predetermined shape made of carbon ink, and a part of the silver pattern is exposed near the end, and a second pattern is made of silver ink of a predetermined shape.
A flexible printed wiring board with an inspection pattern, characterized in that the pattern and a third pattern made of carbon ink are printed and arranged.