JP2004266037A - Resistance substrate and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resistance substrate which can prevent deterioration of performance resulting from displacement in printing of an adhesive layer. <P>SOLUTION: After a first conductive paste 16 including a large amount of silver particles in a binder resin which is mainly formed of a thermosetting resin is printed to an isolation film 15, a resistance paste 17 is printed in the manner that it overlaps on the end of the first conductive paste 16. Next, a second conductive paste 18 including silver particles in the binder resin which is mainly formed of the thermosetting resin is also printed over the resistance paste 17. A narrow protruded part 18a formed at the end of the second conductive paste 18 is extended up to the area over the first conductive paste 16. Next, an adhesive paste 19 is printed over the second conductive paste 18 and a fused resin 21 is ejected and molded into a cavity 20c by supplying such paste to a metal die 20. Thereafter, the isolation film 15 is separated to produce a transfer type resistance substrate where a resistance layer 11 and a terminal layer 12 are exposed within the same plane of a resin molded body 10. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a resistive substrate having a resistor layer and a terminal layer exposed on the same plane of a resin molded product and a method of manufacturing the same, and more particularly, to a resistive substrate using a solderable terminal layer and a method of manufacturing the same.
[0002]
[Prior art]
Conventionally, a resistor layer is formed on a flat surface of a spare substrate by using a thick film printing technique, and a metal terminal is soldered to an end of the resistor layer. After injection molding of the resin molded body so as to cover the whole, by peeling the preliminary substrate from this resin molded body, a resistive substrate called a transfer type in which the resistor layer is exposed on the smooth surface of the resin molded body is known. (For example, see Patent Document 1).
[0003]
In such a transfer-type resistance substrate, the surface of the resin molded body and the surface of the resistance layer are smooth surfaces without any level difference. This has the advantage that the sliding life of the layer is greatly extended. However, since a step of soldering metal terminals to the resistor layer is required before injection molding of the resin molded body, there is a disadvantage that the entire manufacturing process including the injection molding step of the resin molded body becomes complicated. there were.
[0004]
Therefore, in recent years, a transfer-type resistance substrate has been proposed in which a solderable terminal layer is printed on the end of the resistor layer during a series of manufacturing steps, and metal terminals are soldered to the terminal layer after the manufacture. Have been. FIG. 5 is a plan view of a conventional resistor substrate using such a terminal layer, and FIG. 6 is a cross-sectional view of the resistor substrate. As shown in these drawings, a resistor layer is provided on the same plane of the resin molded body 1. 2 and the terminal layer 3 are exposed in a state where their ends overlap each other. A lead electrode layer 4 is formed on the lower surface of the resistor layer 2 so as to reach an overlapping portion with the terminal layer 3, and the lead electrode layer 4 is bonded and fixed to the inner surface of the resin molded body 1 by an adhesive layer 5. Have been.
[0005]
In order to manufacture the resistance substrate configured as described above, first, the terminal layer 3 is printed and baked on the spare substrate 6 indicated by a two-dot chain line in FIG. The resistor layer 2 is printed and fired so as to wrap. Here, the terminal layer 3 is a conductive paste containing a large amount of conductive powder such as silver in a binder resin containing a thermoplastic resin such as polyester as a main component. Poor degree of bonding between powders and no solderability. Further, the resistor layer 2 is a resistor paste containing carbon in a thermosetting resin such as a phenol resin. Next, the lead electrode layer 4 is printed and fired from above the resistor layer 2, and the lead electrode layer 4 covers the overlapping portion between the resistor layer 2 and the terminal layer 3. The lead electrode layer 4 is a conductive paste containing a conductive powder such as silver in a binder resin containing a thermosetting resin such as a phenol resin as a main component, but the content of the conductive powder is smaller than that of the terminal layer 3. Is running low. Next, after printing and baking an adhesive layer 5 made of a thermosetting resin such as an epoxy resin from above the lead electrode layer 4, the spare substrate 6 is supplied to a mold (not shown) to form a thermoplastic molten resin in the cavity. Is injected and cooled and solidified to form the resin molded body 1. At this time, the thermoplastic resin in the conductive paste forming the terminal layer 3 is melted and the porous portion is crushed by the resin pressure, so that the degree of coupling between the conductive powders is increased, and the soldering becomes possible. Thereafter, the preliminary substrate 6 is peeled off from the resin molded body 1 so that the resistor layer 2 and the terminal layer 3 are exposed in the same plane of the resin molded body 1 as shown in FIGS. A resistive substrate is obtained. After the resistance board is manufactured in this manner, an external terminal (not shown) is soldered to an end (right end in FIG. 5) of the terminal layer 3 exposed on the surface of the resin molded body 1. When the resistance substrate is assembled together with other components to complete, for example, a slide type variable resistor, a predetermined output from the external terminal is caused by sliding a slider piece (not shown) on the resistor layer 2. Is obtained.
[0006]
[Patent Document 1]
Japanese Patent No. 2583778 (page 2, FIG. 1-6)
[0007]
[Problems to be solved by the invention]
In the conventional resistance substrate shown in FIGS. 5 and 6, the resistor layer 2, the terminal layer 3, the lead electrode layer 4 and the adhesive layer 5 are all printed using individual masks. It is difficult in terms of manufacturing technology to eliminate printing misalignment. In particular, if the printing misalignment of the adhesive layer 5 causes the distance between the lead electrode layer 4 and the end portion of the adhesive layer 5 (dimension A in FIG. 6) to be largely shifted in the plus direction, There is a problem that the end of the lead electrode layer 4 is easily peeled off from the resin molded body 1. On the other hand, when the dimension A greatly shifts in the negative direction and the adhesive layer 5 protrudes from the end of the lead electrode layer 4 and reaches the lower surface of the terminal layer 3, the terminal layer 3 corresponding to the protruding portion is formed. A large amount of the adhesive layer 5 penetrates into the porous portion of the conductive paste to be formed, and the portion where the adhesive layer 5 has entered during the subsequent injection molding of the resin molded article 1 cannot be crushed by the resin pressure. The degree of coupling between them decreases, and the specific resistance of the terminal layer 3 increases. The adhesive layer 5 protruding up to the terminal layer 3 is present in the width direction of the terminal layer 3, and the terminal layer 3 in contact with the protruding adhesive layer 5 has an overall specific resistance increasing even in the film thickness direction. Therefore, there arises a problem that the resistance value (residual resistance) between the end position S of the slider piece and the external terminal soldered to the end of the terminal layer 3 significantly increases.
[0008]
In the above-described conventional example, the problem of the residual resistance not being caused by the formation of the resistor layer 2 or the lead electrode layer 4 is mainly due to the fact that the adhesive layer is not compared with the binder resin of the resistor layer 2 or the lead electrode layer 4 5 is expected to be due to the high liquidity. Incidentally, the value of the residual resistance when the adhesive layer 5 protruded into the terminal layer 3 and when the adhesive layer 5 did not protrude was evaluated under the same conditions as the other conditions. A result of 0.05Ω was obtained.
[0009]
The present invention has been made in view of such a situation of the related art, and an object of the present invention is to provide a resistance substrate that can prevent performance deterioration due to printing displacement of an adhesive layer.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, in the resistor substrate of the present invention, a resin molded body, a resistor layer and a terminal layer, which are exposed in the same plane of the resin molded body and whose ends overlap each other, A lead electrode layer formed at a position overlapping the lower surface of the resistor layer; and an adhesive layer for fixing the lead electrode layer to an inner surface of the resin molded body, wherein the terminal layer is mainly made of a thermoplastic resin. The lead electrode layer is made of a conductive paste containing conductive powder in a binder resin containing a thermosetting resin as a main component, and the lead electrode layer is made of a conductive paste containing conductive powder in a binder resin as a component. The narrow protruding portion formed in the portion was extended to a position overlapping the lower surface of the terminal layer.
[0011]
According to the resistance substrate configured as described above, since the narrow protrusion formed at the end of the lead electrode layer extends to the position where it contacts the lower surface of the terminal layer, the contact area between the terminal layer and the resin molded body is increased. And the peel strength can be secured by minimizing the decrease of the adhesive layer, and even if the adhesive layer reaches the protruding portion due to printing misalignment, it is possible to prevent the adhesive layer from entering the terminal layer overlapping the protruding portion. In addition, an increase in the residual resistance can be suppressed.
[0012]
In the above configuration, the protruding portion may extend from any position of the end of the lead electrode layer, but it is preferable that the protruding portion is formed at a substantially central position in the width direction of the lead electrode layer.
[0013]
In order to achieve the above object, in the method of manufacturing a resistance substrate according to the present invention, a first conductive paste containing a conductive powder in a binder resin containing a thermoplastic resin as a main component is formed on the flat surface of the preliminary substrate. And a step of printing a resistor paste on the flat surface of the preliminary substrate so as to overlap a part of the first conductive paste. The conductive powder is applied to a binder resin containing a thermoplastic resin as a main component. A step of printing the contained second conductive paste on the resistor paste, a step of printing an adhesive on the second conductive paste, and supplying the spare substrate to a mold and melting the cavity into a cavity A step of injecting a resin, and a step of peeling the preliminary substrate from a resin molded body obtained by cooling and solidifying the molten resin, wherein the projecting portion formed at an end of the second conductive paste is 1 conductivity It is extended until the paste was set this protrusion narrower than the width of the second conductive paste.
[0014]
In a resistor substrate manufactured by such a method, a narrow projection extending to above the first conductive paste is formed at an end of the second conductive paste printed on the resistor paste. When the adhesive strength is printed on the second conductive paste, the peel strength can be secured by minimizing the decrease in the contact area between the solderable terminal layer formed by the first conductive paste and the resin molded body. Even if the adhesive layer reaches the protruding portion due to printing misalignment, it is possible to suppress the adhesive layer from entering the first conductive paste overlapping with the protruding portion, thereby suppressing an increase in residual resistance. .
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a plan view of a resistor substrate according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the resistor substrate, and FIG. 3 is a manufacturing process of the resistor substrate. FIG.
[0016]
As shown in FIGS. 1 and 2, a resistance substrate according to the present embodiment includes a resin molded body 10 having a smooth upper surface, a resistor layer 11 and a terminal layer 12 exposed in the same plane of the resin molded body 10. And a lead electrode layer 13 formed on the lower surface of the resistor layer 11, and an adhesive layer 14 for fixing the lead electrode layer 13 to the inner surface of the resin molded body 10. A terminal insertion hole 10a reaching the terminal layer 12 is formed in the resin molded body 10, and an external terminal (not shown) inserted into the terminal insertion hole 10a is soldered to the terminal layer 12.
[0017]
The resin molded body 10 is formed by injection molding, for example, PCT (polycyclohexane dimethylene terephthalate), but other thermoplastic resins such as 6T nylon, PET, polyether imide, and polyether sulfone can be used. . The resistor layer 11 is made of a thermosetting resin such as phenol containing carbon, and the end of the resistor layer 11 is overlapped on the lower surface of the end of the terminal layer 12. The terminal layer 12 is made of a binder resin containing a thermoplastic saturated polyester resin as a main component and containing conductive powder such as silver at about 60 to 80 vol%. Good solderability is obtained by the pressure. The lead electrode layer 13 is made of a thermosetting resin such as phenol containing conductive powder such as silver at about 50 vol%, and a protruding portion 13 a formed at the center of the end extends to the lower surface of the terminal layer 12. . The width w of the protrusion 13a is set sufficiently narrower than the width W of the lead electrode layer 13. In the case of the present embodiment, W = 1 mm and w = 0.3 mm. I have. The adhesive layer 14 is a thermosetting adhesive such as an epoxy resin, and the adhesive layer 14 is set at a position that does not protrude from the end of the lead electrode layer 13.
[0018]
In order to manufacture the resistance substrate configured as described above, first, as shown in FIG. 3A, a release film (for example, a PPS film) 15 is prepared as a spare substrate, and The first conductive paste 16 is printed using a mask (not shown) and fired. The first conductive paste 16 is, for example, a binder resin containing a thermoplastic saturated polyester resin as a main component and containing about 70 vol% of silver particles. The first conductive paste 16 after printing and baking has a porous portion. , The degree of bonding between silver particles is poor and the silver particles do not have solderability.
[0019]
Next, as shown in FIG. 3B, a resistor paste 17 is printed on the release film 15 using another mask (not shown), and the resistor paste 17 is applied to an end of the first conductive paste 16. Overlap the part. The resistor paste 17 includes, for example, phenol resin containing carbon, and is fired after printing.
[0020]
Next, as shown in FIG. 3C, a second conductive paste 18 is printed on the resistor paste 17 by using another mask (not shown) and baked, and an end of the second conductive paste 18 is formed. The first conductive paste 16 covers the overlapping portion (overlap portion) of the first conductive paste 16 and the resistor paste 17, and the narrow protruding portion 18 a formed at the end of the second conductive paste 18 is connected to the first conductive paste 16. To the middle of the lower surface. The second conductive paste 18 contains, for example, about 50 vol% of silver particles in a phenol resin, and the protrusion 18 a is set sufficiently narrower than the width of the second conductive paste 18.
[0021]
Next, as shown in FIG. 3D, an adhesive paste 19 is printed on the release film 15 using another mask (not shown) so as to cover the second conductive paste 18 except for the protrusions 18a. And bake. The adhesive paste 19 is made of, for example, an epoxy resin, and its end is set so as to be located at the overlapping portion of the first conductive paste 16 and the resistor paste 17, so that even if there is a slight mask shift. The adhesive paste 19 is set so as not to protrude from the protruding portion 18a.
[0022]
Thereafter, as shown in FIG. 3 (e), the release film 15 on which the first conductive paste 16, the resistor paste 17, the second conductive paste 18 and the adhesive paste 19 are formed is placed in a mold 20. The molten resin 21 made of, for example, PCT is injected into the cavity of the mold 20 from the gate 20b in a state where the supply and the tip of the pin 20a provided in the mold 20 abut the first conductive paste 16. At this time, since the thermoplastic saturated polyester resin of the first conductive paste 16 is melted and the porous portion is crushed by the resin pressure, the degree of bonding between the silver particles contained in the first conductive paste 16 increases, A solderable terminal layer 12 is formed. Further, the resistor layer 11 is formed by the resistor paste 17, the lead electrode layer 13 is formed by the second conductive paste 18, and the adhesive layer 14 is formed by the adhesive paste 19. Further, the resin molded body 10 is molded by cooling and solidifying the molten resin 21. Thereafter, as shown in FIG. 3 (f), the release film 15 is peeled from the resin molded body 10 after the mold is opened. Thereby, as shown in FIGS. 1 and 2, a transfer-type resistance substrate in which the resistor layer 11 and the terminal layer 12 are exposed in the same plane of the resin molded body 10 is obtained.
[0023]
After the resistance board is manufactured in this manner, an external terminal (not shown) is inserted into the terminal insertion hole 10a of the resin molded body 10 as described above, and the external terminal is soldered to the surface of the terminal layer 12. Then, if this resistance substrate is assembled together with other components to complete a slide type variable resistor, for example, a slider piece (not shown) is slid on the resistor layer 11 to allow a predetermined amount of the external terminal to move. An output can be obtained (the symbol S in FIG. 1 indicates the end position of this slider piece).
[0024]
According to the resistor substrate according to the embodiment, the protruding portion 13a is formed at the end of the lead electrode layer 13 so as to extend to a position in contact with the lower surface of the terminal layer 12, and a portion corresponding to the protruding portion 13a is formed. Only the contact area between the terminal layer 12 and the resin molded body 10 decreases, but the width w of the protruding portion 13a is set sufficiently smaller than the width W of the lead electrode layer 13. The peel strength of the resin molded body 10 can be secured. In the step of printing the adhesive paste 19 for forming the adhesive layer 14 on the second conductive paste 18 for forming the lead electrode layer 13, as shown in FIG. If the position P ₀ is set close to the end of the second conductive paste 18 and the distance A between the two ends is set as small as possible, the dimension A fluctuates in the plus direction due to printing misalignment and the end of the adhesive paste 19 ends. even part becomes position P _1, be reliably fixed to the second conductive paste 18 inner surface of the (lead electrode layer 13) the resin molded body 10 ends with adhesive paste 19 (adhesive layer 14) of the Can be. On the contrary, as if dimension A by a printing deviation greatly varies in the minus direction, the ends of the adhesive paste 19 becomes a position P ₂ overlapping with the protruding portion 18a of the second conductive paste 18 (protrusion 13a) Also, since the adhesive paste 19 can be prevented from entering the portion overlapping with the protrusion 18a of the first conductive paste 16 forming the terminal layer 12, the resin pressure is applied during the subsequent injection molding of the molten resin 21. The porous portion of the first conductive paste 16 is reliably crushed, and a conductive path with low specific resistance is secured between the terminal position S of the slider piece and the external terminal soldered to the end of the terminal layer 12. Therefore, deterioration of the solderability of the terminal layer 12 and an increase in the specific resistance (residual resistance) can be suppressed.
[0025]
Then, keep resistor substrate according to this embodiment, even if the end portion of the adhesive paste 19 becomes a position P ₂ overlapping with the protruding portion 18a of the second conductive paste 18, the product using the resistance board The residual resistance was about 0.06Ω, which was almost the same value as in the case of the above-mentioned conventional example in which the adhesive did not protrude. This is because the conductive path between the end position S of the slider piece and the external terminal is secured by the terminal layer 12 overlapping the narrow protrusion 13a, but the specific resistance of the terminal layer 12 is extremely high. It is presumed that the ratio to the residual resistance hardly changes even if the width is small.
[0026]
In the above embodiment, the resistance board of the type in which the external terminal inserted into the terminal insertion hole 10a of the resin molded body 10 is soldered to the terminal layer 12 has been described, but the external terminal is directly soldered to the surface of the terminal layer 12. The present invention is also applicable to a resistive substrate of a type to be attached.
[0027]
Further, in the above embodiment, the case where the lead electrode layer 13 and the protruding portion 13a are formed in the same step using the same mask has been described. It can also be formed in a process.
[0028]
【The invention's effect】
The present invention is implemented in the form described above, and has the following effects.
[0029]
Since the narrow protrusion formed at the end of the lead electrode layer (second conductive paste) extends to a position in contact with the lower surface of the terminal layer (first conductive paste), the terminal layer and the resin molded body The peel strength can be ensured by minimizing the decrease in the contact area, and even if the adhesive layer reaches the protruding portion due to printing misalignment, the amount of the adhesive layer entering the terminal layer is reduced, so the terminal layer Can be suppressed from deteriorating the solderability and increasing the specific resistance (residual resistance).
[Brief description of the drawings]
FIG. 1 is a plan view of a resistance substrate according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the resistance substrate.
FIG. 3 is an explanatory view showing a manufacturing process of the resistance substrate.
FIG. 4 is an explanatory diagram showing printing displacement of an adhesive layer.
FIG. 5 is a plan view of a conventional resistive substrate.
FIG. 6 is a sectional view of the resistance substrate.
[Explanation of symbols]
Reference Signs List 10 resin molded body 10a terminal insertion hole 11 resistor layer 12 terminal layer 13 lead electrode layer 13a protrusion 14 adhesive layer 15 release film (preliminary substrate)
16 First conductive paste 17 Resistor paste 18 Second conductive paste 18a Projecting portion 19 Adhesive paste 20 Mold 20a Pin 20b Gate 21 Molten resin

Claims (3)

A resin molded body, a resistor layer and a terminal layer which are exposed in the same plane of the resin molded body and whose ends are overlapped with each other, and a lead formed at a position overlapping at least a lower surface of the resistor layer An electrode layer and an adhesive layer for fixing the lead electrode layer to the inner surface of the resin molded body,
The terminal layer is made of a conductive paste containing a conductive powder in a binder resin containing a thermoplastic resin as a main component, and the lead paste is a conductive paste containing a conductive powder in a binder resin containing a thermosetting resin as a main component. And a narrow protruding portion formed at an end of the lead electrode layer is extended to a position overlapping with a lower surface of the terminal layer. 2. The resistance substrate according to claim 1, wherein said projecting portion is formed at a substantially central position in a width direction of said lead electrode layer. A step of printing a first conductive paste containing conductive powder in a binder resin containing a thermoplastic resin as a main component on a flat surface of the preliminary substrate; and a step of printing the first conductive paste on the flat surface of the preliminary substrate. A step of printing a resistor paste so as to overlap a part thereof; and a step of printing a second conductive paste containing conductive powder on a binder resin containing a thermoplastic resin as a main component on the resistor paste, A step of printing an adhesive on the second conductive paste, a step of supplying the preliminary substrate to a mold and injecting a molten resin into a cavity, and a resin molded body obtained by cooling and solidifying the molten resin Peeling off the preliminary substrate from
A protrusion formed at an end of the second conductive paste extends to above the first conductive paste, and the protrusion is set to be narrower than a width dimension of the second conductive paste. Manufacturing method of the resistance substrate.

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