JPH051201U - Printed circuit board resistance - Google Patents

Abstract

(57) [Abstract] [Purpose] To increase the printing accuracy when a printed resistor is printed on a substrate on which electronic components such as LEDs are mounted by screen printing using a printing ink such as carbon paste. Try to improve the accuracy of the printed resistance value without. [Structure] An LED 13 is mounted on a circuit pattern 12 formed of a printing ink such as silver paste on a membrane 11, and is formed between the LED 13 and the circuit pattern 12 by silk printing or the like with a printing ink such as carbon paste. Printed resistors 14 and 15 are provided, and the printed resistors 14 and 15 are connected via electrodes 16 and 17 to the circuit pattern 12 and the LED 13.
And the electrodes 16 and 17 are branched by the electrodes 18 and 19 and the electrodes 20 and 21, and the printed resistors 14 and 1 are connected.
Connect 5 in parallel.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a printed resistance of a board, and more particularly to a printed resistance in a circuit board on which electronic parts such as LEDs are mounted.

[0002]

[Prior Art]

 When a circuit pattern is printed on a substrate, a resistor paste is mainly formed between electrodes made of silver or the like by printing with a resistance paste mainly composed of carbon. The resistance value of the resistor is set to a desired resistance value by adjusting the specific resistance of the resistance paste or by changing the distance between electrodes, the width of the printing resistance, the thickness of printing, or the like.

Therefore, when the LED 1 is mounted on the circuit pattern 3 of the substrate 2 and the antibody 4 is connected as shown in FIG. 2, the distance d between the electrodes connecting the resistor 4 becomes extremely small. There is. That is, because the LED 1 operates with a relatively large current, a resistor 4 having a low resistance value is used. Since the resistor 4 is a printed resistor, the distance d becomes smaller as the resistance value becomes lower.

Here, the tolerance of the resistance value R of the resistor 4 is determined by the ratio. However, since the distance d is formed by printing, the allowable tolerance is determined by the size of the shape. Therefore, even if the tolerance of the resistance value R is constant, if the value of the resistance value R is low, the distance d becomes small and the width of the printing tolerance becomes narrow. Therefore, the resistance value of the resistor 4 having a low resistance value is much higher than that of the high resistance one, which is a defective product due to defective printing.

[0005]

[Problems to be solved by the device]

 Especially for low resistance printed resistors, the accuracy of the resistance value is greatly affected by the precision of the printing shape, so substrates using low resistance printed resistors have a high defect rate, low yield and low cost. It was a factor of improvement. Therefore, even in the case of a low resistance printing resistor, there is a technical problem to be solved in order to improve the yield of the substrate without widening the tolerance of the resistance value and narrowing the tolerance of the printing shape and dimension. The present invention aims to solve this problem.

[0006]

[Means for Solving the Problems]

 The present invention has been proposed to achieve the above object, and is a resistor provided on a substrate on which electronic components such as LEDs are mounted, the resistor being screen-printed using a printing ink such as carbon. In the printing resistor formed by the above, the printing resistor provides a substrate printing resistor characterized in that two or more electrodes are provided in parallel for both electrodes.

[0007]

[Action]

 In this invention, an LED or other electronic component is mounted, and a printing resistor is formed between predetermined electrodes by means of printing on a circuit board on which connection terminals, electrodes, switch parts, etc. are printed. The print resistance between the predetermined electrodes is divided into two or more pieces, and the divided print resistances are connected in parallel between the predetermined electrodes. Therefore, the dimensional error of the external shape that occurs when the printing resistor or the predetermined electrode is printed is not the error of the combined resistance value of the printing resistors whose values are immediately divided, but the divided printing resistors. It will be reduced according to the number of. Therefore, the accuracy of the resistance value of the printing resistor can be increased without changing the printing accuracy.

[0008]

【Example】

 An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a rear view of a circuit pattern 12 printed on a transparent membrane sheet 11. In the figure, the circuit pattern 12 is screen-printed with a printing ink such as silver paste. An LED 13 is connected to the circuit pattern 12 via printed resistors 14 and 15. The printed resistors 14 and 15 connect the LED 13 and the circuit pattern 12 by electrodes 16 and 17. The electrodes 16 and 17 are branched by the electrodes 18 and 19 and the electrodes 20 and 21, and the print resistors 14 and 15 are connected in parallel to the LED 13.

The distance d between the electrodes 18 and 19 and the electrodes 20 and 21 is increased when the resistance value of the printed resistors 14 and 15 is increased, and is decreased when the resistance value is reduced. Further, the width of the printing resistors 14 and 15, that is, the size in the direction orthogonal to the distance d is small when the resistance value of the printing resistors 14 and 15 is high, and is large when the low resistance value is obtained.

Printing when the widths of the printed resistors 14 and 15 are summed up and the required resistance value is obtained only by one printed resistor without arranging the printed resistors 14 and 15 in parallel. The width of the resistance is substantially the same when the distance d is equal. The printing resistors 14 and 15 are formed, for example, by printing a resistance paste containing carbon or the like as a printing ink on a silk screen or the like, and connecting the printing resistors 14 and 15 in parallel as described above. However, the amount of printing ink is almost equal.

The resistance value R of the printing resistors 14 and 15 for controlling the current flowing through the LED 13 is 1 / R = (1 / R 1 with respect to the resistance value R 1 of the printing resistor 14 and the resistance value R 2 of the printing resistor 15. ) + (1 / R2), the tolerance of the resistance R is ± n, and the tolerances of the resistances R1 and R2 of the printing resistors 14 and 15 are ± 2n. Therefore, if the tolerance of the distance d is ± dn corresponding to the resistance value R ± n, the tolerance of the resistance values R1 and R2 is ± 2dn.

The allowable tolerance of the distance d varies depending on the value when the number of the printing resistors 14 and 15 is two or more, as described above, and therefore depends on the embodiment and the required accuracy of the resistance value. Therefore, the number of printing resistors may be set appropriately. It should be noted that the present invention can be modified in various ways without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified version.

[0013]

[Effect of the device]

 As described in detail above, according to the present invention, a printed resistor is formed between predetermined electrodes by printing on a circuit board on which LEDs and other electronic components are mounted and on which connection terminals, electrodes, switch parts, etc. are printed. In this case, the printing resistance between the predetermined electrodes is divided into two or more plural resistances, and the divided printing resistances are connected in parallel between the predetermined electrodes. However, the dimensional error of the external shape that occurs when printing the above-mentioned printing resistors and specified electrodes does not immediately become the combined resistance value of the printing resistors that are connected in parallel, but reduces according to the number of divided printing resistors. It could be Therefore, if the precision of the printed resistor shape is not changed, the precision of the resistance value of the printed resistor can be significantly improved, the processing cost is hardly increased, and the yield is reduced due to defective printing. Since it does not exist, there is an effect that the total cost can be reduced.

[Brief description of drawings]

FIG. 1 is a rear view showing an embodiment of the present invention.

FIG. 2 is a rear view showing a conventional example.

[Explanation of symbols]

 12 circuit pattern 13 LED 14 and 15 printing resistance 16, 17, 18, 19, 20, 21 electrode d distance

Claims (1)

Claims for utility model registration 1. A resistor provided on a substrate on which an electronic component such as an LED is mounted, the resistor being formed by screen printing or the like using a printing ink such as carbon. The printing resistor according to claim 1, wherein two or more printing resistors are provided in parallel for both electrodes.