JP2008235679A - Manufacturing method of encoder substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encoder substrate where especially a plurality of conduction parts can highly precisely be formed at narrow pitches and surfaces of the conduction parts and a surface of an insulating substrate can be formed to be smooth. <P>SOLUTION: Conductive paste comprising carbon powder and binder resin is printed and a first conduction layer 21 is formed on a transfer plate 30. Conductive paste comprising silver powder and binder resin is printed and a second conduction layer 22 is formed on the first conduction layer 21. An outer shape of a conduction layer 23 formed of the first conduction layer 21 and the second conduction layer 22 is patterned by a laser. First conduction parts 24 are formed on an outer peripheral side of the conduction layer 23 by leaving intervals and second conduction parts 25 on an inner peripheral side by leaving the intervals. They are put in a metal mold and the insulating substrate formed of resin is injection-molded. The intervals between the conduction parts are buried with resin. The transfer plate 30 is peeled and the conduction layer 23 is transferred to an insulating substrate-side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of manufacturing an encoder substrate that can form a plurality of conductive portions with high precision and a narrow pitch, and that can smoothly form the surface of the conductive portions and the surface of an insulating substrate.

Patent Document 1 listed below discloses a method for manufacturing an encoder board.
In the invention described in Patent Document 1, as described in [0014] column to [0022] column of Patent Document 1, first, a film of carbon paste is printed on the carrier film 1 and heated to form a carbon layer. After forming 2, the carrier film 1 is placed in the primary mold 3 and the conductive plastic block 4 is injection molded.

  Subsequently, the conductive plastic block 4 is taken out from the primary mold 3 and the carrier film 1 is peeled off. At this time, the carbon layer 2 is transferred to the conductive plastic block 4 in a pattern, and a conductive block 5 is formed.

Next, when the conductive block 5 is put into a secondary mold 6 and an insulating plastic is injection-molded, and then taken out from the secondary mold 6, the encoder substrate shown in FIG. Complete.
Japanese Patent No. 2882549

  However, in the above encoder substrate manufacturing method, due to the presence of the conductive plastic block having a large film thickness, the flow of insulating resin in the mold is poor. Cannot be properly filled with the insulating resin. Moreover, in the manufacturing method of patent document 1, the pattern interval of the conductive pattern 8 must be controlled by the inner surface shape of the primary mold 3.

  Furthermore, in the invention described in Patent Document 1, after the conductive plastic block 4 is injection-formed, the insulating plastic is injection-molded using another mold.

  As a result, in the manufacturing method described in Patent Document 1, it is difficult to reduce the pitch of the conductive pattern 8, and a step is easily generated between the surface of the conductive pattern 8 and the surface of the insulating plastic. There was a problem that the sliding surface could not be formed. Furthermore, since the conductive plastic block 4 and the insulating plastic are injection-molded using different molds and the mold shape is complicated, there is a problem that the manufacturing method is complicated and the cost is increased.

  Therefore, the present invention is for solving the above-described conventional problems, and in particular, a plurality of conductive portions can be formed with high precision and a narrow pitch, and the surface of the conductive portion and the surface of the insulating substrate can be formed smoothly. An object is to provide an encoder board.

The present invention provides a method for manufacturing an encoder board having a surface region in which conductive portions and insulating substrates are alternately exposed.
(A) a step of printing a conductive paste having conductive particles and a binder resin on the transfer plate to form a conductive layer;
(B) a step of patterning the outer shape of the conductive layer as viewed from above so that a plurality of the conductive portions are formed at intervals in the conductive layer;
(C) placing the conductive layer formed on the transfer plate in a mold, pouring molten resin into the mold, and filling the space between the conductive portions with the resin at this time;
(D) peeling the transfer plate and transferring the conductive layer to the insulating substrate made of the resin;
It is characterized by having.

  In the present invention, since the conductive layer is printed on the transfer plate in the step (a), the thickness of the conductive layer can be reduced, and in the step (c), the resin is spaced between the conductive portions. It can be poured into the inside properly. In addition, after the conductive portion is printed and formed, in the step (b), the outer shape of the conductive layer is patterned to form a plurality of the conductive portions at intervals in the conductive layer. Further, in the present invention, the conductive layer is transferred to the insulating substrate in the step (d).

  By using each of the above steps, according to the present invention, a plurality of the conductive portions can be formed with a high precision and a narrow pitch, and the surface of the conductive portions and the surface of the insulating substrate can be formed smoothly. I can do it. In addition, it is possible to manufacture an encoder board having a surface area in which conductive portions and insulating substrates are alternately exposed at low cost by a simple manufacturing method without requiring a complicated mold as in the prior art. is there.

  In the present invention, it is preferable that the outer shape of the conductive layer is patterned by laser irradiation in the step (b). Thereby, the said electroconductive part can be formed with a narrow pitch with higher precision.

In the present invention,
Between the step (b) and the step (c),
(E) heating the conductive layer to cure the binder resin;
It is preferable to have. Thereby, when patterning the outer shape of the conductive layer, because the conductive layer is not cured, the pattern processing can avoid the problem that the conductive layer is peeled off or damaged from the transfer plate, A highly reliable encoder board with excellent durability can be manufactured.

In the present invention, in the step (a), a first conductive paste having carbon powder and a first binder resin is printed on the transfer plate to form a first conductive layer,
Next, it is preferable to print a second conductive paste having silver powder and a second binder resin on the first conductive layer to form a second conductive layer. As a result, the first conductive layer is exposed from the surface of the encoder substrate, but the structure of the present invention is excellent in environmental resistance, and the second conductive layer containing silver powder is formed to overlap the first conductive layer. The conduction resistance can be reduced.

  In the present invention, using the same kind of thermosetting resin for the first binder resin and the second binder resin improves the adhesion between the first conductive layer and the second conductive layer. This is preferable.

  In the present invention, the second conductive paste preferably contains, as conductive particles (silver powder), silver as a main component and bismuth oxide, carbon, or a composite powder comprising bismuth oxide and carbon. .

  The silver powder composed of the composite powder is less likely to melt (or insoluble) at a heating temperature (baking temperature) for curing the binder resin, compared to silver powder having a high purity. Accordingly, heat generation due to melting can be appropriately suppressed, and as a result, decomposition of the binder resin and the like can be suppressed, adhesion between the first conductive layer and the second conductive layer can be improved, and the conductive property can be improved. The film strength of the layer can be improved.

  According to the encoder substrate manufacturing method of the present invention, it is possible to form a plurality of conductive portions at a narrow pitch with high accuracy and a smooth surface between the conductive portion and the surface of the insulating substrate. .

  1 to 6 show a method for manufacturing an encoder board according to the present embodiment. 1 (a), 2 (a), 3 (a), and 4 to 6 all show the encoder substrate in the manufacturing process as shown in FIGS. 1 (b), 2 (b), and 3. The cross-sectional shape is cut in the film thickness direction from the line AA shown in (b) and viewed from the arrow direction. FIGS. 1B, 2B, and 3B are plan views of FIGS. 1A, 2A, and 3A, respectively.

  In the process shown in FIG. 1, a first conductive layer 21 is formed by screen printing a first conductive paste on a transfer plate 30 formed of, for example, a brass plate. The surface of the transfer plate 30 is mirror-finished in advance. The transfer plate 30 is preferably made of metal. By forming the transfer plate 30 with a metal, the thermal contraction rate can be reduced as compared with the first conductive layer 21 (the transfer plate 30 formed with a metal tends to expand due to heat). The transfer plate 30 is easy to peel off.

  In the present embodiment, the first binder resin is dissolved in the first solvent, and, for example, carbon black and carbon fiber (a pulverized powder of carbon fiber having an average particle diameter of 3 to 30 μm) mixed with the first binder resin. The first conductive paste is used. For example, the first binder resin is 30 to 95% by volume, and the total of carbon black and carbon fiber is 5 to 70% by volume (the total of the first binder resin, carbon black, and carbon fiber excluding the solvent is 100% by volume).

  A stainless steel mask for making the pattern shape of the first conductive layer 21 is used on the surface of the transfer plate 30, and the paste-like first conductive layer 21 is formed on the surface of the transfer plate 30 as shown in FIG. ) Screen print in a ring shape.

  After printing, the first conductive layer 21 is dried, for example, at 100 to 250 ° C. for 10 to 60 minutes using a drying furnace, and the first solvent is evaporated and removed.

  Next, in the step shown in FIG. 2, a paste-like second conductive layer 22 is formed on the first conductive layer 21 in a ring shape as shown in FIG. 2B by screen printing.

  The second conductive paste is mainly composed of a second binder resin, silver as a main component, and bismuth oxide, carbon, or a composite powder containing carbon, bismuth oxide and carbon, or the like in a second solvent. It is preferable that the conductive particles (silver content) are mixed. For example, the second binder resin is 50 to 95% by volume, and the conductive particles are 5 to 50% by volume (the second binder resin excluding the solvent and the total of the conductive particles is 100% by volume). . In the present embodiment, silver powder made of composite powder containing silver, bismuth oxide, and carbon as main components is used as the conductive particles (silver powder).

After printing, using a drying furnace, the screen-printed paste-like second conductive layer 22 is dried, for example, at 100 to 260 ° C. for 10 to 60 minutes, and the second solvent is evaporated and removed.
You may dry the 1st conductive layer 21 and the 2nd conductive layer 22 simultaneously.

  As shown in FIG. 2B, the outer diameter of the second conductive layer 22 is smaller than the outer diameter of the first conductive layer 21, and the inner diameter of the second conductive layer 22 is set to the first conductive layer 22. The ring-shaped second conductive layer 22 is completely formed on the ring-shaped first conductive layer 21 so as to be larger than the inner diameter of the conductive layer 21.

  Next, in the process of FIG. 3, the outer shapes of the first conductive layer 21 and the second conductive layer 22 as viewed from above are patterned by laser irradiation (trimming) as shown in FIG. The first conductive layer 21 and the second conductive layer 22 are fused by laser irradiation. As the laser, a solid-state laser such as a semiconductor laser or a YAG laser can be used.

  As shown in FIG. 3B, a plurality of first conductive portions 24 are spaced apart in the circumferential direction on the outer peripheral side of the conductive layer 23 composed of the first conductive layer 21 and the second conductive layer 22. A plurality of second conductive portions 25 are formed on the inner peripheral side of the conductive layer 23 at intervals in the circumferential direction. In FIG. 3 (b), the first conductive portion 24 and the second conductive portion 25 are formed on the substantially half circumference of the conductive layer 23. In practice, however, the entire circumference of the conductive layer 23 is The first conductive portion 24 and the second conductive portion 25 are formed with a space therebetween.

  Next, the first binder resin contained in the first conductive layer 21 and the second binder contained in the second conductive layer 22 are heated in a heating furnace at a temperature of about 400 ° C. for 1 to 2 hours. The resin is thermoset simultaneously. Accordingly, the first conductive layer 21 has a film structure in which carbon powder is dispersed in a thermoset binder resin, and the second conductive layer 22 has a film structure in which composite powder is dispersed in a thermoset binder resin. Become.

  Here, carbitol acetate, methyl carbitol, ethyl carbitol, butyl carbitol, monoglyme, diglyme, methyltriglyme and the like can be used as the first solvent and the second solvent.

  The first binder resin and the second binder resin may be selected from thermosetting resins such as polyimide resin, bismaleimide resin, epoxy resin, phenol resin, and acrylic resin. The binder resin preferably contains an acetylene-terminated polyisoimide oligomer from the viewpoint of increasing the glass transition temperature (Tg) and improving the heat resistance.

  Next, in the step shown in FIG. 4, the conductive layer 23 formed on the transfer plate 30 is placed in the mold 40. Then, molten epoxy resin, for example, is injected into the cavity 43 of the mold 40. At this time, the epoxy resin appropriately flows in the interval 26 between the first conductive portions 24 and also in the interval between the second conductive portions 25 to fill the interval.

  The temperature of the mold 40 is, for example, 160 to 200 ° C., and the epoxy resin is cured to form the insulating substrate 41. Then, the insulating substrate 41 with the transfer plate 30 is taken out from the mold 40, and the transfer plate 30 is peeled off from the insulating substrate 41 and the conductive layer 23 is transferred to the insulating substrate 41 as shown in FIG. The encoder board 42 is completed.

  FIG. 7 is a plan view of the completed encoder board 42. The plane of the encoder substrate 42 here refers to the peeling surface of the transfer plate 30 as shown in FIG.

  As shown in FIG. 7, the surface of the conductive layer 23 and the surface of the insulating substrate 41 appear on the surface of the encoder substrate 42. In the conductive layer 23, the first conductive layer 21 appears on the surface, and the second conductive layer 22 does not appear on the surface. As shown in FIG. 7, on the surface of the conductive layer 23, a ring-shaped common region 23a and a plurality of A-phase regions 24a projecting outward at a predetermined interval along the outer periphery of the common region 23a. And a plurality of B-phase regions 25a projecting inward at predetermined intervals along the inner periphery of the common region 23a.

  Each A-phase region 24 a is the surface of each first conductive portion 24, and the surface of each B-phase region 25 a is the surface of each second conductive portion 25. The surface of the insulating substrate 41 appears between the A-phase regions 24a and between the B-phase regions 25a.

  FIG. 8 is an enlarged view of a part of the surface of the conductive layer 23 shown in FIG. As shown in FIG. 8, the center line B of the width dimension (dimension in the circumferential direction) of the A-phase area 24a that is closest to each other across the common area 23a and the width dimension (dimension in the circumferential direction) of the B-phase area 25a. The center line C is shifted. In the embodiment of FIG. 8, the half region partitioned by the center line B of the A phase region 24a and the half region partitioned by the center line C of the B phase region 25a define the common region 23a. The remaining region of the A phase region 24a is located at a position facing the space between the B phase regions 25a (insulating substrate 41) and the common region 23a, and the remaining of the B phase region 25a. Is located at a position opposite to the space between the A-phase regions 24a (insulating substrate 41) across the common region 23a.

  A common slider (not shown) relatively slides on the ring-shaped common region 23a. Further, the first slider (not shown) is a first surface in which the A-phase region 24a and the surface of the insulating substrate 41 between the A-phase regions 24a are alternately exposed along the circumferential direction (sliding direction). Relative sliding on the region (first sliding region). Further, the second slider (not shown) is a second surface in which the B-phase region 25a and the surface of the insulating substrate 41 between the B-phase regions 25a alternately appear along the circumferential direction (sliding direction). Relative sliding on the region (second sliding region).

When the first slider slides relatively on the A-phase region 24a, the first slider and the common slider are electrically connected, and an ON (ON) signal is output. On the other hand, when the first slider slides relatively on the insulating substrate 41, the first slider and the common slider are electrically disconnected, and an OFF signal is output. . Then, the ON signal and the OFF signal are alternately repeated, and an A-phase pulse signal (V _A ) is output.

When the second slider slides relatively on the B-phase region 25a, the second slider and the common slider are electrically connected, and an ON (ON) signal is generated. On the other hand, when the second slider slides relatively on the insulating substrate 41, the second slider and the common slider are electrically disconnected, and an OFF signal is generated. Is output. Then, the ON signal and the OFF signal are alternately repeated, and a B-phase pulse signal (V _B ) is output.

  Since the A-phase region 24a and the B-phase region 25a are shifted as shown in FIG. 8, the timing (phase) of the A-phase pulse and the B-phase pulse is 90 degrees (1/4 of one pulse). ) Output is shifted. By measuring the output of each pulse, the rotation state (rotation direction and rotation amount) can be detected.

  In this embodiment, the encoder substrate 42 may be on the rotation side and the slider may be fixed, or the slider may be on the rotation side and the encoder substrate 42 may be fixed. But you can.

The characteristic part of the manufacturing method of the encoder substrate 42 of the present embodiment will be described.
In the present embodiment, the first conductive layer 21 and the second conductive layer 22 are formed on the transfer plate 30 by screen printing in the steps of FIGS. As a result, the conductive layer 23 composed of the first conductive layer 21 and the second conductive layer 22 can be formed thin.

  In this embodiment, in the step of FIG. 3, the outer shape of the conductive layer 23 is patterned to form a plurality of first conductive portions 24 and second conductive portions 25, but the thickness of the conductive layer 23 is thin. Therefore, trimming can be performed appropriately, and the first conductive portion 24 and the second conductive portion 25 can be formed with high accuracy at a narrow pitch.

  In the present embodiment, the outer shape of the conductive layer 23 can be patterned by a laser, electron beam, etching, or the like in the step of FIG. 3, but the outer shape of the conductive layer 23 is particularly patterned by a laser. However, it is preferable that the first conductive portion 24 and the second conductive portion 25 can be formed with high accuracy at a narrow pitch. In the present embodiment, the encoder substrate 42 capable of forming a gap between the first conductive portions 24 and the second conductive portions 25 at about 50 μm and outputting a signal of about 200 to 400 pulses per rotation. Can be manufactured.

  Further, since the thickness of the conductive layer 23 is thin, even when the pitch is narrowed, the insulating substrate 41 shown in FIG. 4 can be formed in the interval 26 of the first conductive portion 24 and the second conductive portion 25 in the molding process. Each of the intervals can be appropriately filled with resin. In addition, in this embodiment, since the conductive layer 23 is transferred to the insulating substrate 41 side by the transfer plate 30, there is a step between the surface of the conductive layer 23 and the surface of the insulating substrate 41 shown in FIG. It is possible to manufacture an encoder substrate that is less likely to occur and has excellent smoothness.

  In this embodiment, a mold 40 for injection molding the insulating substrate 41 is used. However, the shape of the mold 40 is not particularly complicated, and only one injection molding is required, so that the manufacturing cost can be reduced as compared with the conventional one. .

  In the present embodiment, it is preferable to heat-treat the conductive layer 23 after the step of processing the outer shape pattern of the conductive layer 23 shown in FIG. 3 to cure the binder resin contained in the conductive layer 23. Thus, when patterning the outer shape of the conductive layer 23, the conductive layer 23 is not cured, so that the problem that the conductive layer 23 is peeled off or damaged by the outer shape pattern processing is avoided. Thus, the encoder substrate 42 having excellent durability and high reliability can be manufactured.

  In this embodiment, for example, the conductive layer 23 may be formed in a single layer structure, but it is preferable to form the conductive layer 23 in a stacked structure of the first conductive layer 21 and the second conductive layer 22. At this time, carbon powder is added to the first conductive layer 21, and silver powder is added to the second conductive layer 22. Only the first conductive layer 21 containing carbon powder increases the conduction resistance, but the conduction resistance can be lowered by providing the second conductive layer 22 containing silver powder in an overlapping manner. Moreover, the second conductive layer 22 containing silver powder is not exposed on the surface of the encoder substrate 42, and the first conductive layer 21 containing carbon powder is exposed, so that the environment resistance is excellent.

  The first binder resin contained in the first conductive layer 21 and the second binder resin contained in the second conductive layer 22 are preferably the same type of thermosetting resin. The curing temperature of the first binder resin and the second binder resin can be the same or close to each other, and the first binder resin and the second binder resin can be thermally cured in the same heating step. Moreover, the adhesiveness between the said 1st conductive layer 21 and the 2nd conductive layer 22 can be improved by making 1st binder resin and 2nd binder resin the same kind. Here, the “same kind” includes not only the same resin but also a derivative of the resin.

  In the present embodiment, the silver powder as the conductive particles in the second conductive paste is not limited to pure silver powder. That is, a mixed powder or a composite powder may be used as long as the main component is silver.

  In this case, silver powder composed of silver as a main component and bismuth oxide, carbon, or composite powder containing bismuth oxide and carbon as conductive particles (silver powder) in the second conductive paste. It is preferable to use it. Here, “composite powder” is different from “mixed powder” in which silver powder and bismuth oxide powder are simply mixed or “alloy” in which a plurality of metals are melted together. In addition, silver and bismuth oxide, silver and carbon, or silver, bismuth oxide and carbon are included.

  The silver powder composed of the composite powder is less likely to melt (or insoluble) at a heating temperature (baking temperature) for curing the binder resin, compared to silver powder having a high purity. Accordingly, heat generation due to melting can be appropriately suppressed, and as a result, decomposition of the binder resin and the like can be suppressed, adhesion between the first conductive layer and the second conductive layer can be improved, and the conductive property can be improved. The film strength of the layer can be improved.

It is process drawing which shows the manufacturing method of the encoder board | substrate of this embodiment, (a) is sectional drawing which cut | disconnected the said encoder board | substrate in the film thickness direction from the AA line shown in FIG.1 (b), and was seen from the arrow direction. , (B) is a plan view of FIG. It is process drawing performed after FIG. 1, (a) is sectional drawing which cut | disconnected the said encoder board | substrate in the film thickness direction from the AA line shown in FIG.2 (b), and was seen from the arrow direction, (b). Is a plan view of FIG. FIG. 3 is a process diagram performed next to FIG. 2, in which (a) is a cross-sectional view of the encoder substrate taken along the line AA shown in FIG. Is a plan view of FIG. FIG. 4 is a process diagram performed subsequent to FIG. 3, and is a cross-sectional view showing a state in which a conductive layer on a transfer plate is arranged in a mold; FIG. 5 is a process diagram performed next to FIG. Cross section of the completed encoder board, Plan view of the completed encoder board, The elements on larger scale which expanded the surface of the one part conductive layer of FIG.

Explanation of symbols

21 first conductive layer 22 second conductive layer 23 conductive layer 23a common region 24 first conductive portion 24a A phase region 25 second conductive portion 25a B phase region 26 (between first conductive portions) interval 30 Transfer plate 40 Mold 41 Insulating substrate 42 Encoder substrate 43 Cavity

Claims (6)

In a method for manufacturing an encoder board having a surface region in which conductive portions and insulating substrates are alternately exposed,
(A) a step of printing a conductive paste having conductive particles and a binder resin on the transfer plate to form a conductive layer;
(B) a step of patterning the outer shape of the conductive layer as viewed from above so that a plurality of the conductive portions are formed at intervals in the conductive layer;
(C) placing the conductive layer formed on the transfer plate in a mold, pouring molten resin into the mold, and filling the space between the conductive portions with the resin at this time;
(D) peeling the transfer plate and transferring the conductive layer to the insulating substrate made of the resin;
A method of manufacturing an encoder board, comprising:   The method for manufacturing an encoder substrate according to claim 1, wherein in the step (b), the outer shape of the conductive layer is patterned by laser irradiation. Between the step (b) and the step (c),
(E) heating the conductive layer to cure the binder resin;
The manufacturing method of the encoder board | substrate of Claim 1 or 2 which has these. In the step (a), a first conductive paste having carbon powder and a first binder resin is printed on the transfer plate to form a first conductive layer,
The encoder according to any one of claims 1 to 3, wherein a second conductive layer is formed by printing a second conductive paste having silver powder and a second binder resin on the first conductive layer. A method for manufacturing a substrate.   The encoder substrate manufacturing method according to claim 4, wherein the same kind of thermosetting resin is used for the first binder resin and the second binder resin.   The encoder substrate according to claim 4 or 5, wherein the second conductive paste includes, as conductive particles, silver as a main component and bismuth oxide, carbon, or a composite powder comprising bismuth oxide and carbon. Production method.

Images