TW202220503A - Wiring board - Google Patents

Abstract

A wiring board 1 comprises a base film 10, a wiring pattern 20 disposed on the base film 10, and first and second coverlays 30, 40 disposed adjacent to each other on the base film 10 so as to cover the wiring pattern 20, wherein the first coverlay 30 has an overlapped portion 301 on which a portion 401 of the second coverlay 40 is overlapped.

Description

patch panel

The present invention relates to wiring boards.

A flexible printed wiring board (FPC) includes a base film, a circuit, and a cover film. As the base film and the cover film, a plastic film having excellent flexibility such as polyimide is used. The circuit is formed by etching the copper foil attached to the base film. The coverlay film is attached to the circuit by an adhesive (see, for example, Patent Document 1 (paragraphs [0002] to [0004] and FIG. 1 )). [prior art]

[Patent Document 1] Japanese Patent Laid-Open No. 2003-218488.

[The problem to be solved by the invention]

Lamination of the coverlay film on the substrate on which the wiring is formed is performed by using a pressing apparatus. In order to manufacture a large or long flexible printed wiring board, when a coverlay film is laminated on a base material at a time, there is a possibility of increasing the cost due to an increase in the size of the above-mentioned pressing apparatus, a decrease in yield, and the like. problem of the situation.

The problem to be solved by the present invention is to provide a wiring board capable of suppressing cost increase even in the case of manufacturing a large or long wiring board. [means to solve the problem]

[1] The wiring board in the present invention includes: a base material; wirings arranged on the base material; and first and second cover films arranged side by side on the base material to cover the wirings, wherein the first cover film has A repeating portion that is overlapped by a portion of the second cover film.

[2] In the invention described above, the first cover film includes: a first layer that is laminated on the base material and has a first end portion in the overlapping portion; and a second layer that is laminated on the first layer and has a first end portion The repeating portion has a second end portion, wherein the leading end of the first end portion may be located more on the leading end side of the first cover film than the leading end of the second end portion.

[3] In the above-mentioned invention, the following formula (1) can be satisfied, E ₁ <E ₂・・・ (1), wherein in the above-mentioned formula (1), E ₁ is the Young’s modulus of the first layer, E ₂ is the Young's modulus of the second layer.

[4] In the invention described above, the thickness of at least one of the first and second end portions may become thinner toward the distal end side of the first coverlay film.

[5] In the invention described above, the second end portion may be brought closer to the base material toward the front end side of the first coverlay film. [Inventive effect]

In the present invention, by dividing the coverlay film placed on the base material into two, even when a large or long wiring board is to be produced, the coverlay film can be placed on the base material using an existing apparatus, and the Suppression of high cost of wiring boards.

Furthermore, in the present invention, by overlapping a part of the second coverlay on the first coverlay, even when the coverlay is divided into two, it is possible to prevent the wiring from being exposed between the coverlays.

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 is a plan view showing a printed wiring board according to an embodiment of the present invention, Fig. 2 is an enlarged view of part II in Fig. 1, and Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2 .

The printed wiring board 1 of the present embodiment is a flexible printed wiring board (FPC) having a long strip shape. Although not particularly limited, specifically, the length L ₀ of the printed wiring board 1 (length along the X direction in the figure) is 500 mm to 5000 mm (500 mm≦L ₀ ≦5000 mm), and the width W of the printed wiring board 1 ₀ (width along the Y direction in the drawing) is 1 mm to 250 mm (1 mm≦W ₀ ≦250 mm).

In addition, the planar shape of the printed wiring board 1 is not limited to the linear strip shape mentioned above. For example, the printed wiring board 1 may have a shape in which one strip is branched into a plurality of strips at the branch portion. In addition, the width of the printed wiring board 1 does not have to be constant over the entire longitudinal direction, and the width of the printed wiring board 1 may be widened in a part of the longitudinal direction.

Alternatively, the printed wiring board 1 may have a large rectangular planar shape by having a width W ₀ wider than 250 mm (250 mm<W ₀ ≦1000 mm). In addition, the planar shape of the large-scale printed wiring board is not particularly limited to the above, and may be any shape. In this case, a hypothetical rectangle circumscribing the planar shape of the large-scale printed wiring board may have the above-mentioned length L ₀ and width W ₀ .

Such a printed wiring board 1 having a long or large flat shape can be used for applications such as automobiles, industrial machinery, medical equipment, and the like. In addition, the usage of the printed wiring board 1 of the present embodiment is not particularly limited.

As shown in FIGS. 1 to 3 , the printed wiring board 1 includes a base film 10 , a wiring pattern 20 , a first cover film 30 and a second cover film 40 . In addition, for convenience, in FIG. 2, the second cover film 40 is indicated by a dotted chain line. The base film 10 in the present embodiment corresponds to an example of the "substrate" in the present invention, and the wiring pattern 20 in the present embodiment corresponds to an example of the "wiring" in the present invention.

The base film 10 is a flexible and elongated film. The base film 10 is made of a material having electrical insulating properties such as a resin material. Although not particularly limited, the material constituting this base film 10 can be exemplified by, for example, polyimide (PI), liquid crystal polymer (LCP), polyethylene terephthalate (PET), polyethylene naphthalate Ester (PEN), polyetherimide (PEI), polyetheretherketone (PEEK) and polyaramide, etc.

A plurality of wiring patterns 20 are formed on the base film 10 . The wiring pattern 20 is made of a conductive material such as metal or carbon. The metal constituting this wiring pattern 20 can be exemplified by, for example, copper, silver, and gold. In the present embodiment, copper is used as the material constituting the wiring pattern 20 . Although not particularly limited, the wiring pattern 20 is formed by a method such as a subtractive process or a semi-additive process, and the copper foil laminated on the base film 10 is etched into a predetermined shape to form.

In the present embodiment, as shown in FIG. 1 , each wiring pattern 20 extends linearly in the X direction on the base film 10 , and a plurality of wiring patterns 20 are arranged at equal intervals and in parallel with each other. In addition, the number, shape, arrangement, and the like of the wiring patterns 20 are not particularly limited to this, and can be arbitrarily set. In addition, a wiring pattern may be formed on both surfaces of the base film 10, and a through hole or the like may be included in the wiring pattern.

Further, as shown in FIG. 1 , terminal portions 21 are formed at both ends of each wiring pattern 20 , respectively. The terminal portion 21 is, for example, connected to a connector provided on another printed wiring board, an electric wire, or the like, and the printed wiring board 1 is electrically connected to an external electronic circuit via the terminal portion 21 . In addition, the formation position of the terminal part 21 is not limited to the edge part of the wiring pattern 20, An arbitrary position in the wiring pattern 20 can be selected. In addition, the number of the terminal parts 21 in the wiring pattern 20 is not particularly limited, and the terminal parts 21 may not necessarily be formed in the wiring pattern 20 .

As shown in FIGS. 1 to 3 , the first cover film 30 and the second cover film 40 are laminated on the base film 10 to cover the wiring pattern 20 . The first and second cover films 30 and 40 are laminated on the same base film 10 and are arranged on the same main surface of the above-mentioned base film 10 . In the present embodiment, the first and second cover films 30 and 40 are arranged on the base film 10 along the extending direction (longer direction, X direction in the figure) of the base film 10 . In addition, the first and second cover films 30 and 40 do not cover the terminal portions 21 of the wiring pattern 20 , and the above-mentioned terminal portions 21 are exposed from the first and second cover films 30 and 40 .

The first coverlay 30 of the present embodiment has a two-layer structure composed of an outer layer 31 and an inner layer 32 . The outer layer 31 is a film layer for protecting the wiring pattern 20 . On the other hand, the inner layer 32 is a film layer for alleviating the stress concentration when the printed wiring board 1 is bent. The outer layer 31 in the present embodiment corresponds to an example of the "second layer" in the present invention, and the inner layer 32 in the present embodiment corresponds to an example of the "first layer" in the present invention.

The outer layer 31 is formed of a thin film having a long strip shape while being flexible. The outer layer 31 is made of an electrically insulating material such as a resin material. Although not particularly limited, the material constituting this outer layer 31 can be exemplified by, for example, polyimide (PI), liquid crystal polymer (LCP), polyethylene terephthalate (PET), polyethylene naphthalate Diester (PEN), polyetherimide (PEI), polyetheretherketone (PEEK) and polyaramide, etc.

On the other hand, the inner layer 32 of the present embodiment is an adhesive layer having a function of bonding the outer layer 31 to the upper surface 11 of the base film 10 in addition to the function of alleviating the stress concentration when the printed wiring board 1 is bent. As a specific example of the adhesive which comprises this inner layer 32, an epoxy adhesive, an acrylic adhesive, etc. can be illustrated, for example.

As described above, the relatively outer layer 31 is a film layer for protecting the wiring pattern 20 , and the inner layer 32 is a film layer for relaxing stress concentration when the printed wiring board 1 is bent. Therefore, in this embodiment, the inner layer 32 is softer than the outer layer 31 . More specifically, the Young's modulus E 1 of the inner layer 32 and the Young's modulus E ₂ of the outer layer 31 satisfy the relationship of the following formula ( ₂ ).

E ₁ <E ₂・・・ (2)

Materials constituting the outer layer 31 and the inner layer 32 of the first coverlay film 30 are not particularly limited to those described above, as long as the relational expression of the above expression (2) is satisfied.

For example, the outer layer 31 may be formed by using a dry film composed of a photosensitive cover film material instead of the above-mentioned resin film, or a liquid photosensitive cover film material may be applied on the inner layer 32 and then exposed and developed to form a film. The outer layer 31 is formed. Alternatively, the outer layer 31 may be formed by printing a liquid coverlay ink on the inner layer 32 .

Alternatively, the outer layer 31 may be composed of a so-called resist. Specifically, the outer layer 31 can be formed using a dry film made of a photosensitive resist material. Alternatively, after applying a liquid photoresist material on the inner layer 32 , the outer layer 31 may be formed by exposure and development. Alternatively, the outer layer 31 may be formed by printing liquid solder resist ink on the inner layer 32 .

The inner layer 32 may be formed by exposing and developing a liquid photosensitive film material instead of the above-mentioned adhesive layer, and after coating it on the base film 10 . Alternatively, the inner layer 32 may be formed by printing a liquid cover film ink on the base film 10 .

Specific examples of the above-mentioned photosensitive coverlay material and photosensitive resist material include, for example, materials using polyester, epoxy, acrylic, polyimide, and urethane. In addition, as a specific example of the above-mentioned coverlay ink or solder resist ink, for example, ink based on polyimide, epoxy resin, or the like can be exemplified.

The second coverlay 40 also has a function of protecting the wiring pattern 20 . In the present embodiment, the second cover film 40 includes a resin layer and an adhesive layer for bonding the above-mentioned resin layer to the base film 10 . In addition, in FIGS. 3-5, the 2nd coverlay film 40 is shown as a single-layer structure diagram for convenience.

The resin layer of the second cover film 40 is the same as the outer layer 31 of the first cover film 30 described above, and is made of, for example, polyimide (PI), liquid crystal polymer (LCP), polyethylene terephthalate (PET) , Polyethylene naphthalate (PEN), polyetherimide (PEI), polyetheretherketone (PEEK) or polyaramide and other resin films. In addition, the adhesive layer is also composed of an adhesive such as an epoxy resin adhesive or an acrylic adhesive, as in the inner layer 32 of the first coverlay 30 described above, for example.

In addition, the second cover film 40 can be formed by using a dry film, a liquid photosensitive cover film material or a photosensitive resist material, a cover film ink or a solder resist ink. Further, when the base film 10 is made of liquid crystal polymer (LCP) and the second cover film 40 is also made of liquid crystal polymer (LCP), since they can be attached to each other by thermal fusion, the adhesive layer can be omitted.

The leading end portion 401 of this second cover film 40 (the end portion on the +X direction side in the drawing) is overlapped on the first cover film 30 . That is, the first cover film 30 has the overlapping portion 301 overlapped by the leading end portion 401 of the second cover film 40 .

As shown in FIG. 1, the printed wiring board 1 of this embodiment has the 2nd coverlay film 40 of two sheets with respect to the 1st coverlay film 30 which has one sheet. Furthermore, these first and second cover films 30 and 40 are arranged along the extending direction of the base film 10 (X direction in the figure) so as to sandwich the first cover film 30 between the second cover films 40 . Therefore, since both ends of the first cover film 30 are covered by the second cover film 40, respectively, the above-mentioned first cover film 30 has overlapping portions 301 at both ends thereof, respectively.

In addition, the number of repeating portions 301 that the printed wiring board 1 has is not particularly limited. The printed wiring board can have only one repeating portion by including two sheets of cover film. Alternatively, there may be three or more repeating portions by including four or more cover films. In addition, when the printed wiring board has a plurality of overlapping portions, the interval between the overlapping portions can be arbitrarily set. In addition, the lengths of the plurality of coverlay films included in the plurality of printed wiring boards may be substantially the same, or may be different from each other.

As shown in FIGS. 2 and 3, the outer layer 31 of the first cover film 30 having a two-layer structure is in the overlapping portion 301 of one side (the −X direction side in the drawing) in the first cover film 30 described above. Has end 311 . Likewise, the inner layer 32 also has an end portion 321 in the overlapping portion 301 on one side (the −X direction side in the drawing) of the first coverlay film 30 .

Furthermore, in the present embodiment, as shown in FIGS. 2 (plan view) and 3 (cross-sectional views), the leading end (end) 322 of the end portion 321 of the inner layer 32 is larger than the leading end (end) of the end portion 311 of the outer layer 31 The tip) 312 is further located on the tip (tip) 302 side (the -X direction side in FIG. 3 ) of the first coverlay 30 , and the tip 322 of the inner layer 32 constitutes the tip 302 of the first coverlay 30 . That is, the tip 312 of the outer layer 31 is located more inside the overlapping portion 301 (the +X direction side in FIG. 3 ) than the tip 322 of the inner layer 32 . In the overlapping portion 301 , the end 321 of the inner layer 32 is The end portion 311 of the outer layer 31 is exposed.

Although not particularly shown, the overlapping portion 301 on the other side (+X direction side in the drawing) of the first coverlay film 30 is also the same, and the outer layer 31 has an end in the overlapping portion 301, and the inner layer 32 also has an end. The overlapping portion 301 has an end, and the end of the inner layer 32 is located closer to the end 302 of the first cover film 30 than the end of the outer layer 31 (in the +X direction in FIG. 3 ).

At this time, when the cover film of the flexible printed wiring board is divided into plural numbers and the overlapping parts are provided between the cover films, when the flexible printed wiring board is bent, the thickness of the overlapping part will be there. Stress concentration on the wiring pattern occurs at the change point. The stress concentrated at this change point tends to increase as the thickness from the wiring pattern to the surface of the coverlay increases.

On the other hand, in this embodiment, the tip 322 of the inner layer 32 is positioned on the tip 302 side of the first cover film 30 rather than the tip 312 of the outer layer 31, and the shape of the end portion of the first cover film 30 is It is stepped to disperse stress when the flexible printed wiring board 1 is bent.

The length L ₂ of the overlapping portion 301 along the longitudinal direction (X direction in the figure) of the first coverlay film 30 is not particularly limited, but is preferably 0.5 mm to 10 mm (0.5 mm≦L ₂ ≦10 mm), and more preferably 0.5 mm mm～2.0mm (0.5mm≤L ₂ ≤2.0mm). By setting the length L ₂ of the repeating portion 301 to be 0.5 mm or more, the positioning of the first and second cover films 30 and 40 becomes relatively easy. On the other hand, by making the length L ₂ of the overlapping portion 301 10 mm or less and shortening the overlapping portion 301 as much as possible, the influence on the flexibility of the flexible printed wiring board 1 can be suppressed.

Further, the ratio (L ₂ /L ₁ ) of the length L ₂ of the repeating portion 301 to the entire length L ₁ of the first coverlay 30 is preferably 1/20 or less (L ₂ /L ₁ ≦1/20), more preferably 1 /100 or less (L ₂ /L ₁ ≤ 1/100). By setting the ratio (L ₂ /L ₁ ) to 1/20 or less and shortening the overlapping portion 301 as much as possible, the influence on the flexibility of the flexible printed wiring board 1 can be suppressed.

In the case where the first coverlay 30 is formed of a resin film coated with an adhesive, the protrusion of the inner layer 32 from the outer layer 31 can be adjusted by optimizing the pressing pressure and pressing temperature during hot pressing using a pressing device. Therefore, the stepped shape of the end portion of the first cover film 30 shown in FIG. 3 can be formed. In addition, in order to form the stepped shape of the edge part of the 1st coverlay film 30, the thickness, material, etc. of the buffer material used for a press apparatus can be optimized.

On the other hand, when the inner layer 32 is formed by printing or coating, the outer layer 31 may be formed such that the tip 312 of the outer layer 31 is positioned more inside the overlapping portion 301 than the tip of the inner layer 31 .

In addition, the shape of the repeating portion 301 of the first coverlay film 30 is not particularly limited to the stepped shape as described above. FIG. 4 is a cross-sectional view showing a first modification of the end of the overlapping portion in the embodiment of the present invention, and FIG. 5 is a second modification of the end of the overlapping portion in the embodiment of the present invention. sectional view.

For example, as shown in FIG. 4 , the thickness of the end portion 321 of the inner layer 32 of the first coverlay film 30 may become thinner toward the tip end 302 side of the first coverlay film 30 . Thereby, compared with the case shown in FIG. 3, the thickness D ₃ from the wiring pattern 20 at the tip 322 of the inner layer 32 to the surface of the second coverlay 40 can be reduced (D ₁ >D ₃ ), and The stress concentration on the wiring pattern 20 when the printed wiring board 1 is bent is further alleviated. Further, D ₁ is the thickness from the wiring pattern 20 at the tip 322 of the inner layer 32 to the surface of the second coverlay 40 in the example shown in FIG. 3 .

Likewise, the thickness of the end portion 311 of the outer layer 31 of the first cover film 30 may become thinner toward the tip end 302 side of the above-described first cover film 30 . Thereby, compared with the case shown in FIG. 3, the thickness D ₄ from the wiring pattern 20 at the tip 312 of the outer layer 31 to the surface of the second coverlay 40 can be reduced (D ₂ >D ₄ ), and The stress concentration on the wiring pattern 20 when the printed wiring board 1 is bent is further alleviated. In addition, D ₂ is the thickness from the wiring pattern 20 at the tip 312 of the outer layer 31 to the surface of the second coverlay 40 in the example shown in FIG. 3 .

When the outer layer 31 is formed of a resin film, the thickness of the end portion 311 of the outer layer 31 can be gradually reduced by etching or grinding the end portion of the resin film. On the other hand, in the case where the outer layer 31 is formed by printing or coating, the printing conditions (eg, the mesh design of the printing plate, the blade pressure, the printing speed, etc.) or the coating conditions (eg, the coating amount, the base, etc.) can be optimized by optimizing The thickness of the end portion 311 of the outer layer 31 is gradually reduced according to the relative moving speed of the material, etc.). The same goes for the inner layer 32 , by optimizing printing conditions or coating conditions, the thickness of the end portion 321 of the inner layer 32 can be gradually reduced.

Further, any one of the end portion 321 of the inner layer 32 and the end portion 311 of the outer layer 31 may be thinned toward the tip 302 side of the first coverlay film 30 .

In addition, as shown in FIG. 5 , while the thickness of the end portion 321 of the inner layer 32 of the first coverlay 30 becomes thinner toward the tip 302 side of the first coverlay 30 , the end portion 311 of the outer layer 31 may be Over the end 321 of this thinned inner layer 32 protrudes. As a result, the entire end portion 311 of the outer layer 31 is brought closer to the base film 10 toward the front end 30 side of the first coverlay film 30 . Therefore, compared with the case shown in FIG. ₃ , the thickness D5 from the wiring pattern ₂₀ at the tip 312 of the outer layer 31 to the surface of the _second coverlay 40 can be reduced (D2>D5), and further The stress concentration on the wiring pattern 20 when the wiring board 1 is bent is relieved.

As described above, in the present embodiment, by dividing the coverlay film provided on the base film 10 into two, even in the case of manufacturing a large or long printed wiring board 1, the coverlay film 30, 40 is laminated on the base film 10, and the cost of the wiring board 1 can be suppressed.

In addition, in the present embodiment, by overlapping a part of the second coverlay 40 on the first coverlay 30, even when the coverlay is divided into two, it is possible to prevent the wiring pattern 20 from being separated from the coverlays 30 and 40. exposed to each other.

In addition, in the present embodiment, by placing the tip 322 of the inner layer 32 on the tip 302 side of the first coverlay 30 rather than the tip 312 of the outer layer 31, the flexible printed wiring board 1 can disperse stress during bending. Thereby, the stress concentration generated when the flexible printed wiring board 1 is bent can be alleviated, and the occurrence of disconnection of the wiring pattern 20 can be suppressed.

Further, by positioning the tip 322 of the inner layer 32 on the tip 302 side of the first coverlay 30 rather than the tip 312 of the outer layer 31 , the hard outer layer 31 can also be prevented from directly contacting the wiring pattern 20 .

It should be noted that the embodiments described above are described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above-described embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, in the above-described embodiment, the tip 322 of the inner layer 32 is positioned on the tip 302 side of the first coverlay 30 rather than the tip 312 of the outer layer 31 , but the shape of the end of the first coverlay 30 is not particularly limited to this. The front end 322 of the inner layer 32 may coincide with the front end 312 of the outer layer 31 in the longitudinal direction of the printed wiring board 1 (X direction in the figure).

In addition, in the said embodiment, although the 1st coverlay film 30 has a two-layer structure, the 1st coverlay film 30 may be comprised by three or more film layers.

1: printed wiring board 10: base film 11: upper surface 20: wiring pattern 21: terminal part 30: first cover film 301: repeating part 302: tip 31: outer layer 311: end 312: tip 32: inner layer 321: End 322: Tip 40: Second cover film 401: Tip portion II: Section III: Line D ₁ : Thickness D ₂ : Thickness D ₃ : Thickness D ₄ : Thickness D ₅ : Thickness L ₀ : Length L ₁ : Overall length L ₂ : length W ₀ : width

[Fig. 1] Fig. 1 is a plan view showing a printed wiring board in an embodiment of the present invention. [Fig. 2] Fig. 2 is an enlarged view of part II of Fig. 1. [Fig. 3] Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. [Fig. [FIG. 4] FIG. 4 is a cross-sectional view showing a first modification of the end portion of the overlapping portion in the embodiment of the present invention. [Fig. 5] Fig. 5 is a cross-sectional view showing a second modification of the end portion of the overlapping portion in the embodiment of the present invention.

10: base film

11: Above

20: Wiring pattern

30: First cover film

301: Repeat Section

302: Apex

31: Outer part

311: End

12: Apex

32: Inside

321: End

322: Apex

40: Second cover film

401: apex part

D ₁ : Thickness

D ₂ : Thickness

L ₂ : Length

Claims (5)

A wiring board, comprising: substrate; wiring, disposed on the above-mentioned substrate; and The first and second cover films are arranged side by side on the above-mentioned base material to cover the above-mentioned wirings, Wherein the above-mentioned first cover film has a repeating portion overlapped by a part of the above-mentioned second cover film. The wiring board of claim 1, wherein the first cover film includes: a first layer having a first end portion in the repeating portion while being laminated on the base material; and The second layer is laminated on the first layer and has a second end portion in the overlapping portion, The tip of the first end portion is located more on the tip side of the first cover film than the tip of the second end portion. The wiring board of claim 2, wherein the wiring board is a wiring board that satisfies the following formula (1), E ₁ <E ₂・・・ (1), wherein in the above formula (1), E ₁ is the above-mentioned first layer The Young's modulus of , E ₂ is the Young's modulus of the second layer above. The wiring board of claim 2 or 3, wherein the thickness of at least one of the first and second end portions becomes thinner toward the tip side of the first coverlay film. The wiring board according to claim 2 or 3, wherein the second end portion approaches the base material toward the front end side of the first coverlay film.

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