WO2015166588A1 - Rigid-flex substrate with embedded component - Google Patents

Abstract

A rigid-flex substrate (1) with an embedded component (2). Said rigid-flex substrate (1), which has a rigid section (3) in which the component (2) is embedded and a flexible section (4), contains the following: a flexible substrate (10) that comprises an insulating layer (11) with copper foils (12, 13) laminated thereto and has, in the region thereof corresponding to the rigid section (3), an opening (17) that can accommodate the component (2); and a prepreg (20) that is provided so as to cover at least part of one or both surfaces of the flexible substrate (4) and, with the component (2) accommodated inside the opening (17), fills the interior of said opening (17).

Description

Component built-in rigid flex board

The present invention relates to a component built-in rigid flex substrate in which a rigid unit incorporating components and a flexible unit are integrated.

Conventionally, in order to realize a structure for bending and incorporating various electric and electronic devices, a flexible substrate having flexibility, a relatively hard rigid substrate having no flexibility, and the flexible substrate are joined. Various substrates such as a bonded substrate or a rigid flex substrate in which the flexible substrate and the rigid substrate are integrated without forming a bonded portion are used.

In addition, in order to increase the frequency and speed of the transmission signal while preventing an increase in signal noise, various electrical or electronic circuits conventionally mounted on the surface of the substrate as circuit boards incorporated in electric and electronic devices Conventionally, research and development and manufacture of a component built-in substrate having a structure in which the components are built in a substrate, and a component built-in multilayer circuit board formed by laminating the component built-in substrates are performed.

For example, in a flexible circuit board including a rigid portion having an opening and a flexible portion, an electronic component is disposed in the opening of the rigid portion, and interlayer adhesive layers are respectively provided on both sides of the rigid portion. A manufacturing method for obtaining a component built-in rigid flex substrate has been developed by laminating a first substrate and a second substrate having the same by a heat press (see Patent Document 1).

JP 2007-273654 A

In the technique of Patent Document 1 described above, using the interlayer adhesive layer formed on the first substrate and the second substrate, embedding in the opening where the electronic component is disposed and alloy bonding between the conductor and the coated layer are performed ing.

However, when manufacturing a component built-in substrate using the interlayer adhesive layer in this way, the thickness of the built-in component is restricted to a relatively thin component of about 25 μm. For example, in the case of incorporating a large component of 75 μm or more, an adhesive amount sufficient to sufficiently fill the space for providing the incorporated component is required, but the interlayer adhesive layer formed on the first substrate and the second substrate as in Patent Document 1 The amount of adhesive may be insufficient.

In addition, the interlayer adhesive layer needs to be a material for a flexible circuit board, which has low flowability of the adhesive and insufficient filling into the opening. From this point as well, the manufacturing method of Patent Document 1 can not be incorporated in the substrate unless it is a relatively thin and small electronic component.

Furthermore, it is inappropriate to use an adhesive also from the viewpoint of via bonding, and the adhesive has heat resistance, thermal expansion coefficient, mechanical rigidity, etc. in comparison with epoxy resin and polyimide resin which are wiring materials. There is also the problem of poor reliability.

The present invention has been made in view of such problems, and an object of the present invention is to make it possible to incorporate relatively large electronic components in a rigid portion and to secure the reliability of via bonding. To provide a built-in rigid flex substrate.

In order to achieve the above object, the component-embedded rigid flex substrate of the present invention is a component-embedded rigid flex substrate having a rigid portion incorporating components and a flexible portion, and a copper foil is laminated on an insulating layer A flexible base having an opening that can receive the part in a range corresponding to the rigid part, and filling the inside of the opening containing the part, at least one side or both sides of the flexible base And a prepreg laminated so as to cover a portion.

According to the component built-in rigid flex substrate according to the present invention, the component is covered by filling the inside of the opening portion containing the component with a prepreg without using an adhesive or the like as in the prior art. This is because, by adjusting the melt viscosity of the prepreg, even if a large built-in component of, for example, 75 μm or more is accommodated in the opening, the prepreg can be easily filled in the opening without a gap.

In addition, the prepreg is laminated so as to cover at least a part of one side or both sides of the flexible substrate, thereby laminating a copper foil or the like on the surface of the prepreg to perform hole processing with a drill or a laser, etc. Reliable inter-layer connection can be made by paste.

From these facts, the component built-in rigid flex substrate according to the present invention can incorporate relatively large electronic components in the rigid portion, and can also ensure the reliability of via bonding.

It is a top view of the components built-in rigid flex board concerning a 1st example of the present invention. FIG. 2 is a partially enlarged cross-sectional view taken along the line II-II in FIG. FIG. 7 is a cross-sectional view (a) to (d) showing the manufacturing process of the component built-in rigid flex substrate according to the first embodiment. FIG. 7 is a partial enlarged cross-sectional view of a component-embedded rigid flex substrate according to a second embodiment of the present invention. It is a partial expanded sectional view of the components built-in rigid flex substrate concerning the modification of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described below, and can be arbitrarily changed and implemented without changing the gist of the present invention. Further, the drawings used for describing the embodiments schematically show the component built-in rigid flex substrate according to the present invention and the constituent members thereof, and the partial emphasis, enlargement, reduction or omission for the purpose of better understanding In some cases, the scale and shape of the component built-in rigid flex substrate and its constituent members may not be accurately represented. Furthermore, various numerical values used in the embodiments may represent an example, and can be variously changed as needed.

(First embodiment)
In the following, the entire structure of the component-embedded rigid flex substrate 1 according to the first embodiment of the present invention will be described with reference to FIG. Here, FIG. 1 is a plan view of the component built-in rigid flex substrate 1 according to the first embodiment.

As shown in FIG. 1, the component built-in rigid flex substrate 1 according to the first embodiment is a flat substrate having a rectangular planar shape. The component built-in rigid flex substrate 1 is formed with a pair of rigid portions 3 and 3 incorporating electronic components 2 (components) on both sides in the longitudinal direction, and a flexible portion 4 is formed therebetween. Although FIG. 1 illustrates that one electronic component 2 is built in one rigid unit 3, the other rigid unit 3 may also incorporate an electronic component. The number and position are not limited to this. The electronic component is, for example, a resistor, a capacitor, an inductor, an IC, an LSI, or the like, and in this embodiment, a relatively large electronic component of 75 μm or more is incorporated.

In the first embodiment, the component built-in rigid flex substrate 1 has a relatively hard characteristic as a whole, but the flexible portion 4 at the central portion of the substrate is flexible. It can be easily bent.

Although not shown in FIG. 1, on one surface of the component-embedded rigid flex substrate 1 according to the first embodiment, various electric and electronic patterns such as a plurality of wiring patterns, resistors, capacitors, semiconductor elements, etc. Terminals and the like for mounting components are formed. Further, the planar shape of the component-embedded rigid flex substrate 1 is not limited to a rectangular shape, and can be appropriately changed according to the opening shape of the electric / electronic device in which the component-embedded rigid flex substrate 1 is to be embedded.

Next, the detailed structure of the component built-in rigid flex substrate 1 according to the present embodiment will be described. Here, FIG. 2 is a partially enlarged cross-sectional view taken along the line II-II of FIG.

As shown in FIG. 2, the component built-in rigid flex substrate 1 according to the present embodiment is formed of copper on both sides of the insulating layer 11 made of a flexible and insulating insulator such as polyimide and epoxy resin which does not contain glass cloth. The conductive pattern of the foils 12 and 13 is formed, and further, the flexible base 10 covered with the coverlays 14 and 15 for protecting the copper foils 12 and 13 is provided. The copper foils 12 and 13 on both sides of the flexible base 10 are electrically connected by the conductive portion 16 plated with the laser via.

The layer thickness of the insulating layer 11 is about 10 μm to 50 μm, the layer thickness of the copper foils 12 and 13 is about 8 μm to 30 μm, and the layer thickness of the coverlays 14 and 15 is 10 μm to 30 μm. The thickness of the material 10 as a whole is preferably 50 μm to 100 μm.

In the rigid portion 3 of the component built-in rigid flex substrate 1, the flexible substrate 10 is formed with an opening 17 capable of containing the electronic component 2, and the electronic component 2 is disposed in the opening 17. There is. The inside of the opening 17 is filled with a prepreg 20 so as to cover the electronic component 2, and the prepreg 20 is further covered with a cover lay 14 so as to cover both surfaces of the flexible base 10 in the rigid portion 3 of the component built-in rigid flex substrate 1. It is stacked on top of 15. Then, conductor patterns of copper foils 21 and 22 are formed on both sides of the prepreg 20, and the electronic component 2 is attached via an adhesive 23 applied to one of the copper foils 21. Further, the electronic component 2 is electrically conducted by the conductive portions 24 and 25 in which the laser vias communicated from the copper foil 21 to the terminal portion are plated. Furthermore, conductive portions 26 and 27 plated with laser vias corresponding to the conductive portions 16 of the flexible base 10 are also formed on both copper foils 21 and 22 on the prepreg 20, whereby each copper foil 12, 13, 21 and 22 are connected between layers. Then, solder resists 28 and 29 are applied to the rigid portion 3 of the component built-in rigid flex substrate 1.

Next, a method of manufacturing the component built-in rigid flex substrate 1 according to the first embodiment will be described. Here, FIG. 3 is a cross-sectional view (a) to (d) showing a manufacturing process of the component built-in rigid flex substrate according to the first embodiment.

First, as shown in FIG. 3A, a flexible base 10 made of an insulating layer 11, copper foils 12, 13 and cover lays 14, 15 is prepared, and an opening 17 is formed in the flexible base 10.

Subsequently, as shown in FIG. 3B, the pair of prepregs 20a and 20b and the copper foils 21 and 22 are thermally heated from both sides of the flexible substrate 10 in a range corresponding to the rigid portion 3 of the component built-in rigid flex substrate 1. Adhesive lamination is carried out by heating and pressing with a press. Under the present circumstances, the opening hole 20c which can accommodate the electronic component 2 attached via the adhesive agent 23 on one copper foil 21 is formed in one prepreg 20a. With such a configuration, the pair of prepregs 20a and 20b are melted by performing heat pressing so as to cover the opening holes 20c of one of the prepregs 20a that accommodates the electronic component 2 with the other prepreg 20b, thereby opening the opening 17 is filled so as to fill the gap between the electronic component 2 and the electronic component 2.

Then, as shown in FIG. 3C, the prepreg 20 is integrally filled in the opening 17 by the hot press, and the prepreg 20 is formed between the both surfaces of the flexible substrate 10 and the copper foils 21 and 22. A layer is formed.

Next, as shown in FIG. 3D, laser vias are formed at positions corresponding to the terminal portions of the electronic component and the conductive portions 16 of the flexible base 10, and plating is performed to form the respective conductive portions 24 to 27. The electronic component 2 and the respective copper foils 12, 13, 21, 22 are conducted. Furthermore, solder resists 28 and 29 are applied on both sides of the rigid portion 3.

The component built-in rigid flex substrate 1 manufactured in this manner needs to use one having an appropriate melt viscosity as the prepreg 20. For example, the prepreg 20 is laminated in a semi-cured state in which a thermosetting resin such as a polyimide resin or an epoxy resin mixed with an additive such as a curing agent mixed with a fibrous reinforcing material such as glass cloth or carbon fiber. However, the prepreg used in the production of a general rigid substrate has a minimum viscosity of less than 500 ps at 100 ° C. to 150 ° C. In this case, the resin exudes to the flexible portion to make the flexible portion flexible. It will hurt. On the other hand, in order to prevent such resin exudation, the prepreg used for the rigid part of a common rigid flex substrate has a minimum melt viscosity of 5,000 to 35,000 ps at 100 ° C. to 150 ° C. In this case, the resin flow at the time of hot pressing is small, and a void is generated in the opening.

Therefore, the prepreg 20 in the present embodiment has a minimum melt viscosity of 1,000 to 4,000 ps (1,000 ps) at 100 to 150 ° C. (100 ° C. or more and 150 ° C. or less) in order to realize the contradictory requirements as described above. Use more than 4,000 Ps)). Specifically, the prepreg 20 has a minimum melt viscosity of 1,000 to 4,000 ps at 100 to 150 ° C. by adding a filler or the like to the epoxy resin which is a thermosetting resin to increase the melt viscosity. Use one that has been adjusted to

As described above, according to the component built-in rigid flex substrate 1 in the first embodiment, the inside of the opening 17 containing the electronic component 2 is filled with the prepreg 20 without using an adhesive or the like as in the related art. Cover the electronic component 2; This is to accommodate a large internal component of 75 μm or more in the opening by adding a filler to the epoxy resin and adjusting the minimum melt viscosity at 100 ° C to 150 ° C to 1,000 to 4,000 ps. Also, the prepreg 20 can be easily and reliably filled in the opening 17 without a gap.

Further, the prepreg 20 is laminated so as to cover both surfaces of the flexible substrate 10 in the rigid portion 3, thereby laminating the copper foils 21 and 22 on the surface of the prepreg 20 and plating the laser vias with the conductive portions 24 to 27. Thus, reliable interlayer connection can be performed.

From the above, the component-embedded rigid flex substrate 1 in the first embodiment can incorporate relatively large electronic components 2 in the rigid portion 3 and can also ensure via junction reliability.

Second Embodiment
Next, a component built-in rigid flex substrate according to a second embodiment of the present invention will be described with reference to FIG. Here, FIG. 4 is a partially enlarged cross-sectional view of the component built-in rigid flex substrate according to the second embodiment. The same reference numerals are given to the same components as those in the first embodiment, and the detailed description will be omitted.

In the component built-in rigid flex substrate 30 according to the second embodiment as shown in FIG. 4 as well, the electronic component 2 is built in the rigid unit 31 and has a flexible unit 32 which is easily bent.

Specifically, in the component built-in rigid flex substrate 30, conductor patterns of copper foils 42 and 43 are formed on both sides of an insulating layer 41 made of a flexible and insulating insulator such as polyimide and epoxy resin containing no glass cloth. The flexible substrate 40 is provided. Further, the copper foils 42 and 43 on both sides of the flexible base 40 are electrically connected by the conductive portion 44 plated with the laser via. The thicknesses of the insulating layer 41 and the copper foils 42 and 43 are the same as in the first embodiment. Further, in the present embodiment, the insulating layer 41 may contain a glass cloth.

In the rigid portion 31 of the component-embedded rigid flex substrate 30, an opening 45 capable of containing the electronic component 2 is formed in the flexible base 40, and the electronic component 2 is disposed in the opening 45. There is. The inside of the opening 45 is filled with a prepreg 50 so as to cover the electronic component 2, and the prepreg 50 is further laminated so as to cover the entire copper foils 42 and 43 on both sides of the flexible base 40. The conductor patterns of the copper foils 51 and 52 are formed on both sides of the prepreg 50, and the electronic component 2 is attached via the adhesive 53 applied to one of the copper foils 51. In addition, the electronic component 2 is conducted by the conductive portions 54 and 55 in which laser vias communicated from the copper foil 51 to the terminal portion are plated. Furthermore, conductive portions 56 and 57 formed by plating laser vias corresponding to the conductive portions 44 of the flexible base material 40 are also formed on both copper foils 51 and 52 on the prepreg 50, whereby the respective copper foils 42, 43, 51 and 52 are connected between layers. Then, solder resists 58 and 59 are applied to the rigid portion 31 of the component built-in rigid flex substrate 30.

As described above, in the component-embedded rigid flex substrate 30 in the second embodiment, the prepreg 50 covers the rigid portion 31 to the flexible portion 32 in layers without providing the cover lay on the flexible base 40, The numeral 50 protects the copper foils 42 and 43 of the flexible base 40.

The method of manufacturing the component built-in rigid flex substrate 30 in the second embodiment is substantially the same as the method of manufacturing the component built-in rigid flex substrate 1 in the first embodiment. As a different step, in the step of FIG. 3 (b) described above, a pair of prepregs extending from the rigid portion 31 to the flexible portion 32 are heated and pressed together with the copper foils 51 and 52 by heat pressing on both sides of the flexible base 40 Adhesively laminate.

In the component built-in rigid flex substrate 30 in the second embodiment, in addition to the appropriate melt viscosity of the prepreg 20 in the first embodiment, it is necessary to have an elastic modulus that meets the requirement of flexibility in the flexible portion 32. That is, a prepreg having a lower elastic modulus (eg, 2 GPa to 10 GPa) than at least a prepreg used for a rigid substrate is used. Specifically, the prepreg 20 adjusts the elastic modulus by using a polyimide resin or an epoxy resin having a polyimide resin as a skeleton for a thermosetting resin.

As described above, in the component built-in rigid flex substrate 30 in the second embodiment, the flexible portion 32 is also covered with the prepreg 50 so that the flexible base 40 can be extended from the rigid portion 31 to the flexible portion 32 without forming a cover lay. The copper foils 42 and 43 can be protected. Thus, in addition to the effects of the first embodiment, the number of manufacturing steps and the number of parts can be reduced, and a thinner part-embedded rigid flex substrate 30 can be realized.

(Modification)
Next, a component built-in rigid flex substrate according to a modification of the second embodiment will be described with reference to FIG. Here, FIG. 5 is a partially enlarged cross-sectional view of a component built-in rigid flex substrate 1 according to a modification. The same components as those of the first and second embodiments are designated by the same reference numerals and their detailed description will be omitted.

The basic configuration of the component built-in rigid flex substrate 30 ′ shown in FIG. 5 is the same as that of the component built-in rigid flex substrate 30 of the second embodiment, and the electronic component 2 is disposed in the opening 45 of the flexible base 40. ing. And while filling the opening part 45, the prepreg 50 is laminated | stacked on the both surfaces of the flexible base material 40 ranging from the rigid part 31 to the flexible part 32. FIG.

In the modification, a conductor pattern of copper foils 61 and 62 is further formed on both sides of the prepreg 50 in the flexible portion 32. The copper foils 61 and 62 are protected by the cover lays 63 and 64.

Thus, in addition to the effect of the second embodiment, the copper foils 61 and 62 can be easily applied to the flexible portion 32 by covering the prepreg 50 to a range corresponding to the flexible portion 32 of the flexible base 40. Conductor patterns can be added. Although not shown, the conductive portions may be formed on the copper foils 61 and 62 added to the flexible portion 32 so that the copper foils 42 and 43 of the flexible base 40 can be interlayer connected.

This is the end of the description of the embodiment and the modification of the component built-in rigid flex substrate according to the present invention, but the embodiment is not limited to the above embodiment.

Although the component built-in rigid flex substrate 1, 30, 30 'in each of the above-described embodiments and modifications is a so-called four-layer substrate, the number of laminations is not limited to this, applications of the component built-in rigid flex substrate, and requirements It can be suitably changed according to the dimensions etc. For example, in the rigid portion, a prepreg and a copper foil may be further laminated on the outer layer, or a solder resist or the like may be laminated to form a multilayer substrate of four or more layers.

Further, although the conductive portions 16, 24 to 27, 44, 54 to 57 in the respective embodiments are plated with laser vias, other highly reliable via junctions can also be applied. For example, drilling with a drill may be used, or a conductive paste may be embedded.

Furthermore, in the above embodiments, polyimide and epoxy resin not containing glass cloth are used as the insulating layers 11 and 41, but the insulating layer is not limited to epoxy resin, and an insulator having flexibility and insulating property If it is Further, the insulating layer 11 does not necessarily have to be made of only a resin, and if the substrate such as glass cloth is not included, other insulating materials which improve the insulating property and other characteristics are dispersed and held in the resin. It may be done.

Moreover, although the prepregs 20 and 50 are laminated | stacked on both surfaces of the flexible base materials 10 and 40 in said each Example, you may laminate | stack only on any one surface.

(Embodiment of the present invention)
The component built-in rigid flex substrate according to the first embodiment of the present invention is a component built-in rigid flex substrate having a rigid section incorporating components and a flexible section, wherein copper foil is laminated on an insulating layer A flexible base having an opening which is openable to accommodate the component in a range corresponding to the rigid part, and filling the inside of the opening which houses the component, and at least one or both sides of the flexible base And a prepreg laminated to cover the part.

The component-embedded rigid flex substrate according to the second embodiment is the component-embedded rigid flex substrate according to the first embodiment, wherein the prepreg has a minimum melt viscosity of 1,000 ps or more at 100 ° C. or more and 150 ° C. or less 4,000 ps or less. The component-embedded rigid flex substrate according to the third embodiment is the component-embedded rigid flex substrate according to the second embodiment, and a filler is added to the thermosetting resin in the prepreg.

In the component built-in rigid flex substrate according to the fourth embodiment, the component built-in rigid flex substrate according to any of the first to third embodiments, wherein the prepreg is formed on the rigid portion of the flexible base It is stacked only in the corresponding range.

The component-embedded rigid flex substrate according to the fifth embodiment is the component-embedded rigid flex substrate according to any of the first to third embodiments, wherein the prepreg is formed from the rigid portion of the flexible base material. It laminates over the range corresponding to a flexible part. In the component built-in rigid flex substrate according to the sixth embodiment, the component built-in rigid flex substrate according to the fifth embodiment is provided, and the prepreg is made of a polyimide resin or an epoxy resin of polyimide skeleton as a thermosetting resin. It is used.

1, 30, 30 'parts built-in rigid flex board 2 electronic parts (parts)
3, 31 Rigid part 4, 32 Flexible part 10, 40 Flexible substrate 11, 41 Insulating layer 12, 13, 21, 22, 42, 43, 51, 52, 61, 62 Copper foil 14, 15, 63, 64 Cover Rays 16, 24, 25, 26, 27, 44, 54, 55, 56, 57 Conductive parts 17, 45 Openings 20, 20a, 20b, 50 Prepregs 20c Openings 23, 53 Adhesives 28, 29, 58, 59 Solder resist

Claims (6)

A component built-in rigid flex substrate having a rigid unit incorporating components and a flexible unit,
A flexible base material comprising a copper foil laminated on an insulating layer, and having an opening that is openable to accommodate the component in a range corresponding to the rigid portion;
A prepreg filled so as to fill the opening containing the component and to cover at least a part of one side or both sides of the flexible substrate;
Parts built-in rigid flex board with features. The component-embedded rigid flex substrate according to claim 1, wherein the prepreg has a minimum melt viscosity at 1000C to 1500C of 1,000 ps to 4,000 ps. The component-embedded rigid flex substrate according to claim 2, wherein a filler is added to the thermosetting resin in the prepreg. The component built-in rigid flex substrate according to any one of claims 1 to 3, wherein the prepreg is laminated only in a range corresponding to the rigid portion of the flexible substrate. The component built-in rigid flex substrate according to any one of claims 1 to 3, wherein the prepreg is laminated from the rigid portion of the flexible base to a range corresponding to the flexible portion. The component built-in rigid flex substrate according to claim 5, wherein a polyimide resin or an epoxy resin of a polyimide skeleton is used as the thermosetting resin in the prepreg.

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