JP4231305B2 - Resistive substrate and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resistance substrate in which a resistor layer and a terminal layer are exposed in the same plane of a resin molded body and a manufacturing method thereof, and more particularly to a resistance substrate using a solderable terminal layer and a manufacturing method thereof.
[0002]
[Prior art]
Conventionally, a resistor layer is formed on a flat surface of a spare substrate by using a thick film printing technique, a metal terminal is soldered to an end portion of the resistor layer, and a part of the metal terminal and the resistor layer are further soldered. After the resin molded body is injection-molded so as to cover the whole, a resistance substrate called a transfer mold is known in which a resistor layer is exposed on the smooth surface of the resin molded body by peeling the spare substrate from the resin molded body. (For example, refer to Patent Document 1).
[0003]
In such a transfer type resistance substrate, the surface of the resin molded body and the surface of the resistor layer have a smooth surface without a step, so that the resistance body is compared with a resistance substrate in which a resistor layer is printed on an insulating substrate. It has the advantage that the sliding life of the layer is greatly extended. However, since the process of soldering the metal terminal to the resistor layer is required before injection molding of the resin molded body, the entire manufacturing process including the injection molding process of the resin molded body becomes complicated. there were.
[0004]
Therefore, in recent years, a transfer-type resistor board has been proposed in which a terminal layer that can be soldered in a series of manufacturing processes is printed on the end of the resistor layer, and metal terminals are soldered to the terminal layer after manufacture. Has 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. 2 and the terminal layer 3 are exposed in a state where the end portions of the two are overlapped with each other. A lead electrode layer 4 is formed on the lower surface of the resistor layer 2 so as to reach an overlap portion with the terminal layer 3. The lead electrode layer 4 is adhered and fixed to the inner surface of the resin molded body 1 by an adhesive layer 5. Has been.
[0005]
In order to manufacture the resistance substrate configured as described above, first, the terminal layer 3 is printed and fired on the spare substrate 6 indicated by a two-dot chain line in FIG. 6, and then partially over the end of the terminal layer 3. 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 whose main component is a thermoplastic resin such as polyester. However, since the conductive paste has a porous portion, The degree of bonding between the powders is poor and solderability is not achieved. 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 of the resistor layer 2 and the terminal layer 3. The lead electrode layer 4 is a conductive paste in which a conductive resin such as silver is contained in a binder resin whose main component is a thermosetting resin such as a phenol resin, but the content of the conductive powder is compared to the conductive paste of the terminal layer 3. It is running low. Next, an adhesive layer 5 made of a thermosetting resin such as an epoxy resin is printed and baked from above the lead electrode layer 4, and then a spare substrate 6 is supplied to a mold (not shown) to fill the cavity with a thermoplastic molten resin. The resin molded body 1 is molded by cooling and solidifying this. At that time, since the thermoplastic resin in the conductive paste forming the terminal layer 3 is melted and the porous portion is crushed by the resin pressure, the degree of bonding between the conductive powders is increased and soldering is possible. Thereafter, the preliminary substrate 6 is peeled off from the resin molded body 1 to transfer the resistor layer 2 and the terminal layer 3 in the same plane of the resin molded body 1 as shown in FIGS. A resistive substrate is obtained. In addition, after manufacturing the resistance substrate in this way, an external terminal (not shown) is soldered to the end portion (right end portion in FIG. 5) of the terminal layer 3 exposed on the surface of the resin molded body 1. When this resistance substrate is incorporated together with other components to complete, for example, a slide type variable resistor, a predetermined output is output from the external terminal by sliding a slider piece (not shown) on the resistor layer 2. Is obtained.
[0006]
[Patent Document 1]
Japanese Patent No. 2583778 (2nd page, Fig. 1-6)
[0007]
[Problems to be solved by the invention]
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, but each mask is positioned with high accuracy. It is difficult to eliminate printing misalignment in terms of manufacturing technology, and in particular, when the distance between the end portions of the lead electrode layer 4 and the adhesive layer 5 (A dimension in FIG. 6) greatly deviates in the plus direction due to misprinting of the adhesive layer 5 There arises a problem that the end portion of the lead electrode layer 4 is easily peeled off from the resin molded body 1. On the other hand, if the dimension A is greatly shifted in the minus 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, and the portion where the adhesive layer 5 enters during subsequent injection molding of the resin molded body 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 to the terminal layer 3 exists 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 increase in specific resistance even in the film thickness direction. Therefore, there arises a problem that the resistance value (residual resistance) between the terminal position S of the slider piece and the external terminal soldered to the end portion of the terminal layer 3 is remarkably increased.
[0008]
In the above-described conventional example, the problem of residual resistance does not occur with the formation of the resistor layer 2 or the lead electrode layer 4 as compared with the binder resin of the resistor layer 2 and the lead electrode layer 4 mainly. 5 is expected to be due to the high fluidity. By the way, the residual resistance value when the adhesive layer 5 protrudes from the terminal layer 3 and when it does not protrude from the terminal layer 3 are evaluated under the same conditions. The average is 6Ω when protruding and the average when not protruding. A result of 0.05Ω was obtained.
[0009]
The present invention has been made in view of the actual situation of the prior art, and an object of the present invention is to provide a resistance substrate capable of preventing deterioration in performance due to printing misalignment of an adhesive layer.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, in the resistance substrate of the present invention, at least a resin molded body, a resistor layer and a terminal layer that are exposed in the same plane of the resin molded body and overlap end portions, and at least 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 the 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 whose main component is a thermosetting resin. The narrow projecting portion formed on 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, the narrow protrusion formed at the end of the lead electrode layer extends to a position where it comes into contact with the lower surface of the terminal layer. As much as possible, it is possible to secure the peel strength by minimizing the amount of decrease in the thickness, and even if the adhesive layer reaches the protruding portion due to printing misalignment, the adhesive layer can be prevented from entering the terminal layer overlapping the protruding portion. It is possible to suppress an increase in residual resistance.
[0012]
In the above configuration, the protruding portion may extend from any position of the end portion of the lead electrode layer, but it is preferable to form the protruding portion at a substantially central position in the width direction of the lead electrode layer.
[0013]
In order to achieve the above object, in the resistance substrate manufacturing method according to the present invention, a first conductive paste containing conductive powder in a binder resin mainly composed of a thermoplastic resin is placed on a flat surface of a spare substrate. Printing on the flat surface of the preliminary substrate, printing the resistor paste so as to overlap a part of the first conductive paste, and conductive powder on a binder resin mainly composed of a thermosetting resin. A step of printing a second conductive paste containing N on the resistor paste, a step of printing an adhesive on the second conductive paste, and supplying the spare substrate to a mold in the cavity. Including a step of injecting a molten resin, and a step of peeling off the preliminary substrate from a resin molded body obtained by cooling and solidifying the molten resin, and a protrusion formed at an end of the second conductive paste First conductivity It is extended until the paste was set this protrusion narrower than the width of the second conductive paste.
[0014]
In the resistance substrate manufactured by such a method, a narrow protrusion extending to the first conductive paste is formed at the end of the second conductive paste printed on the resistor paste. When the adhesive layer on the second conductive paste is printed on the second conductive paste, the decrease in the contact area between the solderable terminal layer formed of the first conductive paste and the resin molding can be reduced as much as possible to ensure the peel strength. In addition, even if the adhesive layer reaches the protruding portion due to printing misalignment, the adhesive layer can be prevented from entering the first conductive paste overlapping the protruding portion, so that an increase in residual resistance can be suppressed. .
[0015]
DETAILED DESCRIPTION OF THE INVENTION
1 is a plan view of a resistance substrate according to an embodiment of the present invention, FIG. 2 is a sectional view of the resistance substrate, and FIG. 3 is a manufacturing process of the resistance substrate. It is explanatory drawing which shows.
[0016]
As shown in FIGS. 1 and 2, the resistance substrate according to this embodiment includes a resin molded body 10 having a smooth upper surface, and 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 10 a 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 10 a is soldered to the terminal layer 12.
[0017]
The resin molded body 10 is, for example, one obtained by injection molding of PCT (polycyclohexanedimethylene terephthalate), but other thermoplastic resins such as 6T nylon, PET, polyetherimide, polyethersulfone, etc. can be used. . The resistor layer 11 is a thermosetting resin such as phenol containing carbon, and the end portion of the resistor layer 11 is overlapped with the lower surface of the end portion of the terminal layer 12. The terminal layer 12 contains about 60 to 80 vol% of conductive powder such as silver in a binder resin mainly composed of a thermoplastic saturated polyester resin. As will be described later, the resin when the resin molded body 10 is injection-molded. Good solderability can be obtained by the pressure. The lead electrode layer 13 contains about 50 vol% of conductive powder such as silver in a thermosetting resin such as phenol, and the protruding portion 13 a formed at the center of the end extends to the lower surface of the terminal layer 12. . The width dimension w of the protruding portion 13a is set to be sufficiently narrower than the width dimension W of the lead electrode layer 13. In this embodiment, W = 1 mm and w = 0.3 mm. Yes. 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, a release film (for example, PPS film) 15 is prepared as a spare substrate as shown in FIG. The first conductive paste 16 is printed and baked using a mask (not shown). The first conductive paste 16 is a binder resin containing, for example, a thermoplastic saturated polyester resin as a main component and contains about 70 vol% of silver particles. The first conductive paste 16 after printing and baking has a porous portion. Therefore, the degree of bonding between silver particles is poor and solderability is not achieved.
[0019]
Next, as shown in FIG. 3B, the resistor paste 17 is printed on the release film 15 using another mask (not shown), and this resistor paste 17 is applied to the end of the first conductive paste 16. Overlapping the part. The resistor paste 17 is, for example, a phenol resin containing carbon and is baked after printing.
[0020]
Next, as shown in FIG. 3C, the second conductive paste 18 is printed and fired on the resistor paste 17 using another mask (not shown), and the end of the second conductive paste 18 is baked. The overlapping portion (overlap portion) of the first conductive paste 16 and the resistor paste 17 is covered by the portion, and the narrow protrusion 18 a formed at the end of the second conductive paste 18 is formed in the first conductive paste 16. Extend to the middle of the lower surface. The second conductive paste 18 includes, for example, about 50 vol% silver particles in phenol resin, and the protrusion 18 a is set to be sufficiently narrow compared to the width dimension 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 protrusion 18a. And fired. 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 even if there is a slight mask shift It is set so that the adhesive paste 19 does not 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 formed on a mold 20. The molten resin 21 made of, for example, PCT is injected from the gate 20 b into the cavity of the mold 20 in a state where the tip of the pin 20 a provided in the mold 20 is abutted against 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 is increased, A solderable terminal layer 12 is formed. 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 formed by cooling and solidifying the molten resin 21, and then the release film 15 is peeled off from the resin molded body 10 after the mold is opened as shown in FIG. 3 (f). Thus, 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 manufacturing the resistance substrate in this way, external terminals (not shown) are inserted into the terminal insertion holes 10 a of the resin molded body 10 as described above, and the external terminals are soldered to the surface of the terminal layer 12. Then, if this resistance substrate is incorporated 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 value from the external terminal. An output can be obtained (reference S in FIG. 1 represents the end position of this slider piece).
[0024]
According to the resistance substrate according to the above-described embodiment, the protruding portion 13a extending to the position in contact with the lower surface of the terminal layer 12 is formed at the end of the lead electrode layer 13, and the portion corresponding to the protruding portion 13a is formed. However, the contact area between the terminal layer 12 and the resin molded body 10 is reduced, but the width dimension w of the protruding portion 13a is set sufficiently narrower than the width dimension W of the lead electrode layer 13, so that the terminal layer The peel strength with respect to 12 resin molded bodies 10 can be ensured. Further, 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 brought close to the end of the second conductive paste 18 and the distance A between both ends is set as small as possible, the dimension A varies in the positive direction due to printing misalignment, and the end of the adhesive paste 19 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 do. 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) However, since it is possible to prevent the adhesive paste 19 from entering the portion of the first conductive paste 16 that forms the terminal layer 12 that overlaps the protruding portion 18a, the resin pressure is applied during the subsequent injection molding of the molten resin 21. 1 is reliably crushed, and a conductive path having a low specific resistance is ensured between the terminal position S of the slider piece and the external terminal soldered to the end of the terminal layer 12. Therefore, the deterioration of the solderability of the terminal layer 12 and the increase of 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 where the adhesive did not protrude in the conventional example described above. This is ensured by the terminal layer 12 where the conductive path between the terminal position S of the slider piece and the external terminal overlaps the narrow protrusion 13a, but the specific resistance value of the terminal layer 12 is originally extremely high. It is presumed that the ratio to the residual resistance hardly changes even when the width is narrow.
[0026]
In the embodiment described above, 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. However, the external terminal is soldered directly to the surface of the terminal layer 12. The present invention is also applicable to the type of resistor substrate to be attached.
[0027]
In the above-described embodiment, the case where the lead electrode layer 13 and the protruding portion 13a are formed in the same process using the same mask has been described. However, the lead electrode layer 13 and the protruding portion 13a are differently formed using different masks. It can also be formed by a process.
[0028]
【The invention's effect】
The present invention is implemented in the form as 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 amount of decrease in the contact area can be reduced as much as possible to ensure the peel strength, 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 It is possible to suppress the deterioration of the solderability and increase of 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 misalignment of an adhesive layer.
FIG. 5 is a plan view of a resistance substrate according to a conventional example.
FIG. 6 is a sectional view of the resistance substrate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Resin molding 10a Terminal insertion hole 11 Resistor layer 12 Terminal layer 13 Lead electrode layer 13a Protrusion part 14 Adhesion layer 15 Release film (preliminary board)
16 First conductive paste 17 Resistor paste 18 Second conductive paste 18a Protrusion 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 that are exposed in the same plane of the resin molded body and have ends overlapped, and a lead formed at a position that overlaps at least the 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 conductive powder in a binder resin whose main component is a thermoplastic resin, and the conductive paste containing conductive powder in a binder resin whose main component is a thermosetting resin. A resistance board comprising: a narrow projecting portion formed at an end of the lead electrode layer extending to a position overlapping the lower surface of the terminal layer.   2. The resistance substrate according to claim 1, wherein the protruding portion is formed at a substantially central position in the width direction of the lead electrode layer. Printing a first conductive paste containing conductive powder in a binder resin mainly composed of a thermoplastic resin on a flat surface of a spare substrate; and forming the first conductive paste on the flat surface of the spare substrate. A step of printing a resistor paste so as to overlap a part, a step of printing a second conductive paste containing conductive powder in a binder resin mainly composed of a thermosetting resin on the resistor paste, A step of printing an adhesive on the second conductive paste, a step of supplying the spare substrate to a mold and injecting a molten resin into the cavity, and a resin molding obtained by cooling and solidifying the molten resin Peeling the spare substrate from the body,
The protrusion formed at the end of the second conductive paste is extended onto the first conductive paste, and the protrusion is set to be narrower than the width of the second conductive paste. A method for manufacturing a resistance substrate.

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