WO2022242839A1

WO2022242839A1 - Electronic apparatus comprising composite structure

Info

Publication number: WO2022242839A1
Application number: PCT/EP2021/063217
Authority: WO
Inventors: Jyri Kaija; Mika Kolari
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2021-05-19
Filing date: 2021-05-19
Publication date: 2022-11-24

Abstract

An electronic apparatus (1) comprising a composite structure (2), the composite structure (2) forming an outer surface of said apparatus (1) and comprising a thermoplastic polymer matrix (3) and a fabric element (4) forming a surface layer (5) of the composite structure (2). The fabric element (4) is impregnated by a part of said thermoplastic polymer matrix (3). The fabric element (4) may have an elasticity large enough to allow the fabric element (4) to be thermoformed, three-dimensionally, together with the thermoplastic polymer matrix (3). Preferably, the fabric element (4) is configured to deform without rupturing at a temperature above the melting point of the thermoplastic polymer matrix (3). The composite structure (2) may be configured to be thermoformed at pressure high enough to impregnate the fabric element (4) with the thermoplastic polymer matrix (3).

Description

ELECTRONIC APPARATUS COMPRISING COMPOSITE STRUCTURE

TECHNICAL FIELD

The disclosure relates to an electronic apparatus comprising a composite structure.

BACKGROUND

Mobile electronic apparatuses such as smartphones, tablets, and laptops are preferably both durable and lightweight, and have high enough bending stiffness. Fiber reinforced composite materials are commonly used to achieve similar objectives, e.g., in the area of motorsports.

For example, fiber reinforced composite material comprising a thermoset polymer matrix such as epoxy and woven fabric reinforcement is popular due to its good fatigue strength and relatively low cost. However, thermoset polymers are extremely brittle, have low impact- toughness, and are very difficult to recycle because the thermoset cannot be remolded or reshaped; only the reinforcing fiber used can be reclaimed.

Furthermore, the surface of the composite structure may require additional finishing in the form of several hard surface paint and/or coating layers applied to flatten the rough and wavy composite surface and to create a strong, scratch-resistant, smooth, and dirt-repellant surface, which in turn results in additional manufacturing steps like sanding and thermal or UV curing between coating layers. A further known solution is to adhere a fabric material such as polyurethane leather to the outer surface of the composite surface using glue.

Hard coating paints are typically applied in several layers, each layer having a thickness of about 0.1 mm, increasing the thickness of a composite structure such as an apparatus housing. Polyurethane leather similarly increases the composite structure thickness of at least 0.4 mm, including the thickness added by the adhesive layer.

Since consumer electronics get continuously thinner and more lightweight, the thickness and weight of structural and cover materials needs reducing without affecting the durability of the apparatus. Furthermore, a reduced number of manufacturing steps, and hence reduced manufacturing time and costs, is desirable. SUMMARY

It is an object to provide an improved composite structure for an electronic apparatus. The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures.

According to a first aspect, there is provided an electronic apparatus comprising a composite structure, the composite structure forming an outer surface of the apparatus and comprising a thermoplastic polymer matrix and a fabric element forming a surface layer of the composite structure. The fabric element is impregnated by a part of the thermoplastic polymer matrix.

Such a solution allows for an apparatus having a structure, such as a housing, with increased strength, stiffness and toughness and/or reduced thickness. Furthermore, the thermoplastic manufacturing process is very suitable for mass production, and the formability of the structure is improved when compared to dry fabrics since the plasticized matrix acts as a lubricant between fibers. The thermoplastic polymer matrix has very good impact resistance and damage tolerance. Since the matrix can be melted the composite structure can be remolded and easily recycled. Furthermore, thermoplastic composites are less dense than, e.g., thermosets, making the thermoplastic suitable for weight critical applications. Thermoplastic composites also facilitate a high level of automatization, reduces production lead time, allows high production capacity, and generates products with high consistency.

In a possible implementation form of the first aspect, the composite structure is a housing of the electronic apparatus, providing improved protection to the more sensitive components within the apparatus without increasing the thickness or weight of the apparatus.

In a further possible implementation form of the first aspect, the fabric element is not adhered to the thermoplastic polymer matrix by means of an adhesive layer, facilitating a reduction in the number of steps necessary for manufacture and the thickness and weight of the apparatus.

In a further possible implementation form of the first aspect, the fabric element is configured to bond thermally and/or chemically with the thermoplastic polymer matrix, allowing a bond which prevents separation between fabric element and matrix when subject to wear and over time. In a further possible implementation form of the first aspect, the fabric element is a sheet material comprising a plurality of layers, a first layer being a carrier layer and a second layer forming the surface layer of the composite structure, allowing the second layer to have different characteristics than the first layer such as, e.g., providing specific haptic characteristics or preventing photodegradation.

In a further possible implementation form of the first aspect, the second layer comprises a thermosetting polymer, the thermosetting polymer optionally being polyurethane, allowing the outer layer of the composite structure to have an increased resistance to heat, corrosion, and mechanical creep.

In a further possible implementation form of the first aspect, the first layer is applied at a top of the thermoplastic polymer matrix and/or the second layer is applied on top of the first layer, such that the first layer is fixedly joined to, or partially within, the matrix and the second layer provides additional characteristics and/or protection to the surface of the first layer.

In a further possible implementation form of the first aspect, the thermoplastic polymer matrix comprises at least one of polyamide, polypropylene, thermoplastic urethane, high density polyethylene, polypropylene sulfide, polycarbonate, or polylactic acid, allowing for use of a variety of materials.

In a further possible implementation form of the first aspect, the composite structure further comprises a cover layer applied onto the fabric element, the cover layer comprising a coating or a further fabric element layer providing additional protection to the outer surface of the composite structure and preventing fiber print-through from the fabric element or reinforcement fibers.

In a further possible implementation form of the first aspect, the cover layer comprises a transparent polymer, allowing the fabric element of the composite structure to be visible.

In a further possible implementation form of the first aspect, the thermoplastic polymer matrix comprises reinforcement fibers, improving the toughness of the composite structure. In a further possible implementation form of the first aspect, the reinforcement fibers are one of dispersed unidirectionally within the thermoplastic polymer matrix or arranged in a reinforcement fiber layer enclosed by, and impregnated with, the thermoplastic polymer matrix, allowing the type of reinforcement to be selected to fit a specific manufacturing process or product.

In a further possible implementation form of the first aspect, surface irregularities of the fabric element are smaller than surface irregularities of the thermoplastic polymer matrix, improving the smoothness of the outer surface of the composite structure.

In a further possible implementation form of the first aspect, a coefficient of friction of the fabric element is lower than a coefficient of friction of the thermoplastic polymer matrix, allowing the fabric element to provide a relatively smoother outer surface to the composite structure, e.g., improving the cleanability of the structure.

In a further possible implementation form of the first aspect, the fabric element is heat resistant to a temperature above a melting point of the thermoplastic polymer matrix, the temperature preferably being between 120 °C and 160 °C, allowing the composite structure to be thermoformed without damaging the fabric element.

In a further possible implementation form of the first aspect, the fabric element has an elasticity large enough to allow the sheet material to be thermoformed together with the thermoplastic polymer matrix at a pressure exceeding 1 Bar, reducing the number of manufacturing steps necessary for forming the composite structure.

In a further possible implementation form of the first aspect, the fabric element is configured to deform without rupturing at a temperature above the melting point of the thermoplastic polymer matrix facilitating the manufacture of the composite structure.

In a further possible implementation form of the first aspect, the fabric element is configured to be thermoformed three-dimensionally without rupturing.

In a further possible implementation form of the first aspect, the composite structure is configured to be thermoformed at pressure high enough to impregnate the fabric element with the thermoplastic polymer matrix, allowing the composite structure and fabric element to be joined together and consolidated into one integral and solid component.

In a further possible implementation form of the first aspect, the fabric element is made of interlacing and/or bonding fibers, allowing the use of one integral and continuous fabric element within the composite structure.

In a further possible implementation form of the first aspect, the fabric element is a woven or a non-woven sheet material, providing maximum flexibility when it comes to choosing the fabric element.

According to a second aspect, there is provided a method for manufacturing a housing for an electronic apparatus, the method comprising the steps of impregnating a fabric element with a thermoplastic polymer matrix, thermoforming the thermoplastic polymer matrix and the fabric element into a three-dimensional composite structure, the fabric element forming a surface layer of the composite structure, and cooling the composite structure.

Such a method allows mass manufacturing of apparatuses wherein, e.g., the housing has an increased impact resistance and/or a reduced thickness and weight. Furthermore, the thermoplastic manufacturing process improves the formability of the composite structure when compared to dry fabrics since the plasticized matrix acts as a lubricant between fibers. The thermoplastic polymer matrix has very good impact resistance and damage tolerance. Since the matrix can be melted the composite structure can be remolded and easily recycled.

In a possible implementation form of the second aspect, the method further comprises a first step of applying a first layer of the fabric element at a top of the thermoplastic polymer matrix, and applying a second layer of the fabric element on top of the first layer, such that the first layer is fixedly joined to, or partially within, the matrix and the second layer provides additional characteristics and/or protection to the surface of the first layer.

In a further possible implementation form of the second aspect, the method further comprises a last step of providing a cover layer onto the fabric element, the cover layer being configured to form an outer surface of the housing. This allows for an increase in surface durability and prevention of fiber print-through from the fabric element or reinforcement fibers. In a further possible implementation form of the second aspect, the method does not comprise adhering the fabric element to the thermoplastic polymer matrix by means of a separate adhesive layer, facilitating a reduction in the number of steps necessary for manufacture and the thickness and weight of the apparatus.

These and other aspects will be apparent from the embodiment s) described below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present disclosure, the aspects, embodiments, and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

Fig. 1 shows a schematic cross-sectional view of an electronic apparatus comprising a composite structure in accordance with an example of the embodiments of the disclosure;

Fig. 2 shows a schematic cross-sectional view of an electronic apparatus comprising a composite structure in accordance with an example of the embodiments of the disclosure.

DETAILED DESCRIPTION

Figs. 1 and 2 show examples of embodiments of an electronic apparatus 1, such as a smartphone or tablet, comprising a composite structure 2, the composite structure 2 forming an outer surface of the apparatus 1 and comprising a thermoplastic polymer matrix 3 and a fabric element 4 forming a surface layer 5 of the composite structure 2, the fabric element 4 being impregnated by a part of the thermoplastic polymer matrix 3.

The composite structure 2 forms an outer surface of the apparatus 1, the composite structure 2 may be the housing, i.e., the back cover and/or side frame, of the electronic apparatus 1.

The composite structure 2 comprises a thermoplastic polymer matrix 3. The thermoplastic polymer matrix 3 may comprise at least one of polyamide, polypropylene, thermoplastic urethane, high density polyethylene, polypropylene sulfide, polycarbonate, or polylactic acid. Furthermore, the composite structure 2 comprises a fabric element 4 forming a surface layer 5 of the composite structure 2. The fabric element 4 may be made of interlacing and/or bonding fibers, and/or be a woven or a non-woven sheet material. The material may be a thermoplastic such as polyester, polyamide, or thermoplastic polyurethane. The fabric element 4 may have a decorative function, i.e., comprise a specific print or texture. The fabric element 4 may comprise, e.g., pearlescent polyester or artificial polyurethane leather.

Surface irregularities of the fabric element 4 may be smaller than surface irregularities of the thermoplastic polymer matrix 3. Furthermore, the coefficient of friction of the fabric element 4 may be lower than the coefficient of friction of the thermoplastic polymer matrix 3.

The fabric element 4 may be a sheet material comprising one integral material layer, as shown in Fig. 1. The fabric element 4 may also be a sheet material comprising a plurality of layers, a first layer 4a being a carrier layer and a second layer 4b forming the surface layer 5 of the composite structure 2, as shown in Fig. 2.

The first layer 4a may be applied at a top of the thermoplastic polymer matrix 3 and/or the second layer 4b may be applied on top of the first layer 4a. The second layer 4b may be laminated on top of the first layer 4a by means of, e.g., heat or pressure.

The second layer 4b may comprise a thermosetting polymer, the thermosetting polymer optionally being polyurethane. The second layer 4b may be textured and/or have properties for achieving a specific haptic feeling, smoothness, friction, water contact angle, or cleanability.

Furthermore, the fabric element 4 and/or the thermoplastic polymer matrix 3 may comprise special pigments or other additives to achieve pearlescent, color, metallic, or reflective effects.

The fabric element 4, at least the first layer 4a, is impregnated by a part of the thermoplastic polymer matrix 3. By impregnate is meant any process in which the thermoplastic polymer matrix 3 is at least partially melted, i.e. plasticized, such that it can at least partially wet the fabric element 4, i.e. the fabric element 4 is partially coated or overmolded by the same thermoplastic polymer as in the matrix 3. The plasticized thermoplastic polymer matrix 3 penetrates the fabric element 4 by filling the voids between the fibers of the fabric element 4, wetting the fibers by the matrix and such that good adhesion between fibers and matrix is established.

In other words, the fabric element 4 is not adhered to the thermoplastic polymer matrix 3 by means of a separate adhesive layer such as glue. Joining of components by means of impregnation forms a stronger bond than conventional use of glue. Furthermore, a fully seamless structure is achieved.

The fabric element 4 may be configured to bond thermally and/or chemically with the thermoplastic polymer matrix 3.

The fabric element 4 may be heat resistant to a temperature above a melting point of the thermoplastic polymer matrix 3, the temperature preferably being between 120 °C and 160 °C. Optionally, the temperature may be up to 220 °C. The fabric element 4 may, in other words, be configured to deform without rupturing at a temperature above the melting point of the thermoplastic polymer matrix 3. The temperatures for thermoforming a thermoplastic polymer is, nevertheless, substantially lower than the temperatures used in conventional thermoforming.

Furthermore, the fabric element 4 may have an elasticity large enough to allow the fabric element 4 to be thermoformed together with the thermoplastic polymer matrix 3. More specifically, the fabric element 4 may have an elasticity large enough to allow the sheet material to be thermoformed together with the thermoplastic polymer matrix 3 at a pressure exceeding 1 Bar. When vacuum forming, the pressure may be around 1 Bar. However, when using compression tools, the pressure may be significantly higher, up to around 10 Bar. The fabric element 4 may be configured to be thermoformed three-dimensionally without rupturing.

In summary, the fabric element 4 is preferably chemically and thermally compatible with the thermoplastic polymer matrix 3, heat resistant enough to survive the thermo forming process temperatures, and elastic enough to survive three-dimensional forming. The plasticized thermoplastic polymer matrix 3 acts as a lubricant between the fibers of the fabric element 4, facilitating the three-dimensional forming.

The composite structure 2 may be configured to be thermoformed at a pressure high enough to impregnate the fabric element 4 with the thermoplastic polymer matrix 3, i.e. some of the melted thermoplastic polymer penetrates the fabric element 4 and joins the fabric element 4 and the thermoplastic polymer matrix 3.

The composite structure 2 may also comprise a cover layer 6 applied onto the fabric element 4, as shown in Fig. 2, the cover layer 6 comprising a coating or a further fabric element layer. The cover layer 6 may comprise a transparent polymer.

The thermoplastic polymer matrix 3 may comprise reinforcement fibers 7. The reinforcement fibers 7 may be either dispersed unidirectionally within the thermoplastic polymer matrix 3 or be arranged in a reinforcement fiber layer enclosed by, and impregnated with, the thermoplastic polymer matrix 3. The reinforcement fibers 7 may comprise of glass, carbon, aramid, flax or other natural fibers, or hybrid textiles.

The present disclosure further relates to a method for manufacturing a housing for an electronic apparatus 1. The method comprises the steps of impregnating a fabric element 4 with a thermoplastic polymer matrix 3, and thermoforming the thermoplastic polymer matrix 3 and the fabric element 4 into a three-dimensional composite structure 2, the fabric element 4 forming a surface layer 5 of the composite structure 2. The method furthermore comprises the step of cooling the composite structure 2. In other words, the method does not comprise adhering the fabric element 4 to the thermoplastic polymer matrix 3 by means of a separate adhesive layer.

The method may further comprise a first step, executed before the above-mentioned step of impregnating the fabric element 4 with the thermoplastic polymer matrix 3, of applying a first layer 4a of the fabric element 4 at a top of the thermoplastic polymer matrix 3, and applying a second layer 4b of the fabric element 4 on top of the first layer 4a.

The method may furthermore comprise a last step of providing a cover layer 6 onto the fabric element 4, the cover layer 6 being configured to form an outer surface of the housing.

The various aspects and implementations have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure. As used in the description, the terms “horizontal”, “vertical”, “left”, “right”, “up” and “down”, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”, “upwardly”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.

Claims

1. An electronic apparatus (1) comprising a composite structure (2), said composite structure (2) forming an outer surface of said apparatus (1) and comprising

-a thermoplastic polymer matrix (3); and

-a fabric element (4) forming a surface layer (5) of said composite structure (2), said fabric element (4) being impregnated by a part of said thermoplastic polymer matrix (3).

2. The electronic apparatus (1) according to claim 1, wherein said fabric element (4) is not adhered to said thermoplastic polymer matrix (3) by means of an adhesive layer.

3. The electronic apparatus (1) according to claim 1 or 2, wherein said fabric element (4) is configured to bond thermally and/or chemically with said thermoplastic polymer matrix (3).

4. The electronic apparatus (1) according to any one of the previous claims, wherein said fabric element (4) is a sheet material comprising a plurality of layers, a first layer (4a) being a carrier layer and a second layer (4b) forming said surface layer (5) of said composite structure (2).

5. The electronic apparatus (1) according to claim 4, wherein said second layer (4b) comprises a thermosetting polymer, said thermosetting polymer optionally being polyurethane.

6. The electronic apparatus (1) according to claim 5, wherein said first layer (4a) is applied at a top of said thermoplastic polymer matrix (3) and/or said second layer (4b) is applied on top of said first layer (4a).

7. The electronic apparatus (1) according to anyone of the previous claims, wherein said thermoplastic polymer matrix (3) comprises at least one of polyamide, polypropylene, thermoplastic urethane, high density polyethylene, polypropylene sulfide, polycarbonate, or polylactic acid.

8. The electronic apparatus (1) according to any one of the previous claims, wherein said composite structure (2) further comprises a cover layer (6) applied onto said fabric element (4), said cover layer (6) comprising a coating or a further fabric element layer.

9. The electronic apparatus (1) according to any one of the previous claims, wherein said thermoplastic polymer matrix (3) comprises reinforcement fibers (7).

10. The electronic apparatus (1) according to claim 9, wherein said reinforcement fibers (7) are one of dispersed unidirectionally within said thermoplastic polymer matrix (3) or arranged in a reinforcement fiber layer enclosed by, and impregnated with, said thermoplastic polymer matrix

(3)·

11. The electronic apparatus (1) according to anyone of the previous claims, wherein surface irregularities of said fabric element (4) are smaller than surface irregularities of said thermoplastic polymer matrix (3).

12. The electronic apparatus (1) according to anyone of the previous claims, wherein a coefficient of friction of said fabric element (4) is lower than a coefficient of friction of said thermoplastic polymer matrix (3).

13. The electronic apparatus (1) according to anyone of the previous claims, wherein said fabric element (4) is heat resistant to a temperature above a melting point of said thermoplastic polymer matrix (3), said temperature preferably being between 120 °C and 160 °C.

14. The electronic apparatus (1) according to anyone of claims 4 to 13, wherein said fabric element (4) has an elasticity large enough to allow said sheet material to be thermoformed together with said thermoplastic polymer matrix (3) at a pressure exceeding 1 Bar.

15. A method for manufacturing a housing for an electronic apparatus (1), said method comprising the steps of:

-impregnating a fabric element (4) with a thermoplastic polymer matrix (3),

-thermoforming said thermoplastic polymer matrix (3) and said fabric element (4) into a three- dimensional composite structure (2), said fabric element (4) forming a surface layer (5) of said composite structure (2),

-cooling said composite structure (2).

16. The method according to claim 15, further comprising a first step of applying a first layer (4a) of said fabric element (4) at a top of said thermoplastic polymer matrix (3), and applying a second layer (4b) of said fabric element (4) on top of said first layer (4a).

17. The method according to claim 15 or 16, further comprising a last step of providing a cover layer (6) onto said fabric element (4), said cover layer (6) being configured to form an outer surface of said housing.