A printed circuit board and a camera module for reinforcing temperature deformation

Abstract

The present invention discloses a printed circuit board and a camera module for reinforcing temperature deformation, which relates to the technical field of electronic product cameras and solves the technical problem that the printed circuit board in the prior art is deformed due to thermal expansion and contraction. The printed circuit board includes a printed circuit board substrate and a temperature deformation reinforcing layer. The temperature deformation reinforcing layer includes at least two metal layers with different coefficients of thermal expansion that are stacked on top of each other. The printed circuit board substrate is attached to the temperature deformation reinforcing layer, and the bending deformation direction of the temperature deformation reinforcing layer is opposite to the deformation direction of the printed circuit board substrate. By attaching metal layers with different coefficients of thermal expansion to the printed circuit board, when the temperature of the printed circuit board changes, heat is transferred to the metal layers, and the metal layers are bent and deformed under the action of the thermal bimetal, so that the bending deformation direction of the metal layers is opposite to the deformation direction of the printed circuit board substrate, and the bending deformation of the metal layers can be used to resist the deformation of the printed circuit board.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic product cameras, and more specifically, to a printed circuit board for reinforcing temperature deformation and a camera module. Background Art

[0002] As a video input device, cameras are widely used in technical fields such as video conferencing, monitoring devices, and mobile phone consumer products. The printed circuit board is a main component of the camera, and the camera module transmits electrical signals through the printed circuit board.

[0003] With the wide application of cameras, cameras are often in extremely cold or hot environments. Especially as the usage time of the camera extends, the temperature of the chip for capturing images increases significantly. Since the printed circuit board is usually a thin film structure, it is easily affected by thermal expansion and contraction due to temperature, resulting in local concave or convex deformations, thus leading to the problem of unstable back focus between the chip and the lens, and causing the captured images to be unclear. In the prior art, the deformation of the printed circuit board is usually compensated by the method of voice coil motor focusing, but the voice coil motor can only adjust the lens and cannot compensate for the deformation of the printed circuit board. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to overcome the deficiencies of the prior art. On the one hand, a printed circuit board for reinforcing temperature deformation is provided to solve the technical problem that the printed circuit board in the prior art generates deformation due to thermal expansion and contraction.

[0005] The technical solution adopted by the present invention to solve this technical problem is as follows:

[0006] A printed circuit board for reinforcing temperature deformation, comprising:

[0007] A printed circuit board substrate, including two opposite surfaces, with electronic components disposed on one of the surfaces; and,

[0008] A temperature deformation reinforcing layer, including at least two metal layers with different coefficients of thermal expansion, and at least two of the metal layers are stacked on top of each other;

[0009] The other surface of the printed circuit board substrate is attached to the temperature deformation reinforcing layer, and the bending deformation direction of the temperature deformation reinforcing layer is opposite to the deformation direction of the printed circuit board substrate.

[0010] Based on the above technical solution, the printed circuit board for reinforcing temperature deformation can be further improved as follows.

[0011] Optionally, the temperature deformation reinforcing layer includes a first metal layer and a second metal layer, and the coefficient of thermal expansion of the first metal layer is greater than that of the second metal layer.

[0012] Optionally, the first metal layer is disposed between the second metal layer and the printed circuit board substrate, or the second metal layer is disposed between the first metal layer and the printed circuit board substrate.

[0013] Optionally, the thickness of the first metal layer is equal to the thickness of the second metal layer.

[0014] Optionally, the thickness of the printed circuit board substrate is 0.3 - 2 mm, and the thickness of the temperature deformation reinforcement layer is 0.15 - 2 mm.

[0015] Optionally, the material of the first metal layer is Ni22Cr3, and the material of the second metal layer is Ni36.

[0016] Optionally, an adhesive layer is disposed between the printed circuit board substrate and the temperature deformation reinforcement layer, and the temperature deformation reinforcement layer is adhered to one side of the printed circuit board substrate where no electronic components are provided through the adhesive layer.

[0017] Optionally, the temperature deformation reinforcement layer includes an enlarged end and a contracted end, and the two enlarged ends are disposed on both sides of the contracted end. The overall shape of the temperature deformation reinforcement layer is the same as the overall shape of the printed circuit board substrate.

[0018] In a second aspect, the present invention further provides a camera module, including an imaging chip and the above - mentioned printed circuit board for reinforcing temperature deformation. The imaging chip is disposed on the printed circuit board for reinforcing temperature deformation and is located on the side where electronic components are provided.

[0019] Based on the above - mentioned technical solutions, the camera module can be further improved as follows.

[0020] Optionally, a bracket is disposed on the printed circuit board substrate, and a camera assembly located above the imaging chip and a voice coil motor for driving the camera assembly to move are mounted on the bracket.

[0021] Compared with the prior art, the beneficial effects of the printed circuit board for reinforcing temperature deformation provided by the present invention are:

[0022] By laminating metal layers with different coefficients of thermal expansion on the printed circuit board, when the temperature of the printed circuit board changes, heat is transferred to the metal layers. Under the action of the thermal bimetal, the metal layers bend and deform, making the bending and deformation direction of the metal layers opposite to the deformation direction of the printed circuit board substrate. The bending and deformation of the metal layers can resist the deformation of the printed circuit board, thereby maintaining the flatness of the printed circuit board and achieving the effect of preventing the printed circuit board from deforming due to thermal expansion and contraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0024] Figure 1 It is a schematic structural diagram of a printed circuit board for reinforcing temperature deformation according to the present invention;

[0025] Figure 2 is Figure 1 a schematic structural diagram of the printed circuit board in

[0026] Figure 3 applied to a camera module;

[0027] In the figure:

[0028] 1 - First metal layer; 2 - Second metal layer; 3 - Printed circuit board substrate; 4 - Adhesive layer; 51 - Enlarged end; 52 - Shrinkage end; 6 - Imaging chip; 7 - Camera assembly; 8 - Bracket; 9 - Voice coil motor. Specific embodiments

[0029] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following will describe the technical solutions of the present invention in detail. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other implementation manners obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0030] Embodiment 1:

[0031] The present invention provides a printed circuit board for reinforcing temperature deformation. As Figure 1 shown, it includes a printed circuit board substrate 3 and a temperature deformation reinforcement layer. The temperature deformation reinforcement layer further includes two metal layers with different coefficients of thermal expansion, namely the first metal layer 1 and the second metal layer 2. The first metal layer 1 and the second metal layer 2 can be laminated into an integral structure by methods such as hot pressing, double casting, or fusion. An adhesive layer 4 is provided between the temperature deformation reinforcement layer and the printed circuit board substrate 3, and the temperature deformation reinforcement layer is adhered to the printed circuit board substrate 3 through the adhesive layer 4.

[0032] The thermal expansion coefficient of the first metal layer 1 is greater than the thermal expansion coefficient of the second metal layer 2. The material of the first metal layer 1 is Ni22Cr3, and the material of the second metal layer 2 is Ni36. Of course, the first metal layer 1 can also be made of brass, nickel, Fe-Ni-Cr, Fe-Ni-Mn or Mn-Ni-Cu alloy, and the second metal layer can also be made of Ni34-50% Invar alloy.

[0033] When the temperature of the printed circuit board substrate 3 rises, heat is transferred to the first metal layer 1 and the second metal layer 2. Since the thermal expansion coefficient of the first metal layer 1 is greater than the thermal expansion coefficient of the second metal layer 2, the length of the first metal layer 1 is elongated relative to the length of the second metal layer 2, causing the temperature deformation reinforcement layer to bend and deform toward one side of the second metal layer 2. When the temperature of the printed circuit board substrate 3 decreases, the length of the first metal layer 1 is shortened relative to the length of the second metal layer 2, causing the temperature deformation reinforcement layer to bend and deform toward one side of the first metal layer 1.

[0034] Generally, various electronic components are integrated on the printed circuit board substrate 3, and various electronic components transmit electrical signals through the printed circuit board substrate 3. When the electronic components are working, they usually generate a lot of heat, causing the printed circuit board substrate 3 to be concave toward the side where the electronic components are not integrated. The present invention utilizes the characteristic that the temperature deformation reinforcement layer bends and deforms when the temperature changes, so that the bending deformation direction of the temperature deformation reinforcement layer is opposite to the deformation direction of the printed circuit board substrate 3, which can effectively compensate or suppress the deformation of the printed circuit board substrate 3. Thereby maintaining the flatness of the printed circuit board and achieving the effect of preventing the printed circuit board from being deformed due to thermal expansion and contraction.

[0035] It is understandable that for a general printed circuit board substrate 3, the direction of deformation of the printed circuit board substrate 3 of this model can be pre-determined by baking. If the printed circuit board substrate 3 is concave toward the side where the electronic components are not integrated, the first metal layer 1 of the temperature deformation reinforcement layer is attached between the printed circuit board substrate 3 and the second metal layer 2 by means of adhesive layer 4, so that the bending deformation direction of the temperature deformation reinforcement layer is opposite to the deformation direction of the printed circuit board substrate 3. When the temperature of the printed circuit board substrate 3 changes, the bending deformation of the temperature deformation reinforcement layer can resist the deformation of the printed circuit board substrate 3. Of course, depending on the different arrangement of the copper wires on the printed circuit board substrate 3, the direction of the concave printed circuit board substrate 3 may also be toward the side where the electronic components are integrated. At this time, it is only necessary to interchange the positions of the first metal layer 1 and the second metal layer 2, so that the second metal layer 2 of the temperature deformation reinforcement layer is attached between the printed circuit board substrate 3 and the first metal layer 1 by means of adhesive layer 4, which can also make the bending deformation of the temperature deformation reinforcement layer resist the deformation of the printed circuit board substrate 3.

[0036] As shown Figure 3 in the figure, specifically, the temperature deformation reinforcement layer is attached to the side of the printed circuit board substrate 3 where no electronic components are provided. The temperature deformation reinforcement layer includes an enlarged end 51 and a contracted end 52. The two enlarged ends 51 are arranged on both sides of the contracted end 52, making the overall shape of the temperature deformation reinforcement layer in a "worker" shape. The width of the enlarged end 51 is the same as the width of the printed circuit board substrate 3, and the distance between the two enlarged ends 51 is the same as the length of the printed circuit board substrate 3, making the overall outer shape of the temperature deformation reinforcement layer the same as the overall outer shape of the printed circuit board substrate 3. Among them, according to different heat-receiving conditions of the printed circuit board substrate 3, the opening direction of the "worker"-shaped temperature deformation reinforcement layer can be either along the width direction of the printed circuit board substrate 3 or along the length direction of the printed circuit board substrate 3.

[0037] Such a design is convenient for the temperature deformation reinforcement layer to be aligned and attached to the printed circuit board substrate 3 on the one hand; on the other hand, when the bending deformation of the temperature deformation reinforcement layer is too large, it may cause excessive bending of the printed circuit board substrate 3. By designing the temperature deformation reinforcement layer into the shape of the contracted end 52, the bending deformation strength of the temperature deformation reinforcement layer can be reduced, so that the bending deformation strength of the temperature deformation reinforcement layer matches the deformation of the printed circuit board substrate 3. In addition, the contracted end 52 can also ensure the bending deformation direction of the temperature deformation reinforcement layer, so that the bending deformation part accurately acts on the deformed part of the printed circuit board substrate 3.

[0038] The temperature deformation reinforcement layer of the present invention is not limited to the two-layer structure of the first metal layer 1 and the second metal layer 2. According to the force condition of the deformed part of the printed circuit board substrate 3, the bending stress of the temperature deformation reinforcement layer can also be adjusted by three, four, five or even more metal layers. Of course, a heat insulation layer with a certain length can also be arranged between the first metal layer 1 and the second metal layer 2 to make the temperature deformation reinforcement layer bend in multiple segments, so as to better maintain the flatness of the printed circuit board substrate 3.

[0039] Embodiment 2:

[0040] The present invention also provides a camera module, as Figure 2 shown in the figure, which includes an imaging chip 6, a camera component 7, a bracket 8, and the above-mentioned printed circuit board for reinforcing temperature deformation. The imaging chip 6 is integrated on the printed circuit board substrate 3, the bracket 8 is pasted on the printed circuit board substrate 3, the camera component 7 is installed on the bracket 8, and the camera component 7 is located directly above the imaging chip 6. The temperature deformation reinforcement layer is attached to the side of the printed circuit board substrate 3 opposite to the imaging chip 6.

[0041] Generally, for the cameras used in mobile phones, tablets or laptops, the thickness of the printed circuit board substrate 3 is usually 0.3 - 0.5 mm. If the printed circuit board substrate 3 is deformed, it will cause the back focal length between the camera module and the imaging chip 6 to be unstable, resulting in the phenomenon of temperature drift. In the present invention, a temperature deformation reinforcement layer with a thickness of 0.15 mm is attached to the side of the printed circuit board substrate 3 opposite to the imaging chip 6. The first metal layer 1 is located between the printed circuit board substrate 3 and the second metal layer 2, and the thickness of the first metal layer 1 is equal to the thickness of the second metal layer 2. Since the printed circuit board substrate 3 is an overhead structure on the side of the temperature deformation reinforcement layer, when the temperature of the printed circuit board substrate 3 rises, it is easy to deform towards the side of the temperature deformation reinforcement layer. Therefore, by attaching the first metal layer 1 with a large coefficient of thermal expansion between the second metal layer 2 and the printed circuit board substrate 3, the deformation of the printed circuit board substrate 3 can be resisted by the bending deformation of the temperature deformation reinforcement layer.

[0042] It can be understood that for the cameras used in vehicle-mounted videos, surveillance cameras or projectors, the thickness of the printed circuit board substrate 3 is usually 0.5 - 2 mm. Then, the thickness of the temperature deformation reinforcement layer can be designed to be 0.15 - 2 mm, so that the bending stress of the temperature deformation reinforcement layer can resist the deformation of the printed circuit board substrate 3, achieving the purpose of maintaining the flatness of the printed circuit board substrate 3.

[0043] It should be noted that in some camera modules, a voice coil motor 9 for driving the movement of the camera assembly 7 is installed on the bracket 8. However, the voice coil motor 9 can only adjust the camera assembly 7 and cannot compensate for the deformation of the printed circuit board. Moreover, the voice coil motor 9 usually has limitations on the stroke specifications. In the present invention, by attaching the temperature deformation reinforcement layer to the printed circuit board substrate 3, not only can the flatness of the printed circuit board substrate 3 be maintained, but also when taking images with the same clarity, a voice coil motor 9 with a smaller stroke specification can be selected, thereby achieving the purpose of reducing the production cost of the camera module.

[0044] Embodiment 3:

[0045] The present invention is specifically applied to the printed circuit board substrate 3 of a certain mobile phone camera module. The thickness of the printed circuit board substrate 3 is 0.3 mm, and the electronic components integrated on the printed circuit board substrate 3 are the same. The thickness of the added temperature deformation reinforcement layer is 0.1 mm, and the thickness of the adhesive layer 4 is 0.04 mm. Among them, the material selected for the first metal layer 1 is Ni22Cr3, and the material selected for the second metal layer 2 is Ni36. The deformation results of the printed circuit board substrate 3 along the optical axis direction are as follows:

[0046] When the temperature of the printed circuit board substrate 3 without the temperature deformation reinforcement layer rises from 23°C to 85°C, the center point of the printed circuit board substrate 3 sinks by 62.63 μm.

[0047] When the temperature of the printed circuit board substrate 3 with the temperature deformation reinforcement layer installed increases from 23 °C to 85 °C, the center point of the printed circuit board substrate 3 concaves by 0.6344 μm.

[0048] When the temperature of the printed circuit board substrate 3 without the temperature deformation reinforcement layer decreases from 23 °C to -40 °C, the center point of the printed circuit board substrate 3 concaves by 78.68 μm.

[0049] When the temperature of the printed circuit board substrate 3 with the temperature deformation reinforcement layer installed decreases from 23 °C to -40 °C, the center point of the printed circuit board substrate 3 concaves by 0.5972 μm.

[0050] Thus, it can be seen that the temperature deformation reinforcement layer has the functions of compensating and suppressing the temperature deformation of the printed circuit board substrate 3, can ensure the flatness of the printed circuit board substrate 3 within the range of -40 °C to 85 °C, and a good reinforcement effect can be achieved with a thickness of only 0.1 mm for the temperature deformation reinforcement layer. The entire printed circuit board substrate 3 and the temperature deformation reinforcement layer are connected and formed by pasting through the adhesive layer 4, and the assembly process is simple, which is suitable for the large-scale production and manufacturing of camera modules.

[0051] As described above, only the specific embodiments of the present invention are provided, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention.

Claims

1. A printed circuit board for reinforcing temperature deformation, characterized in that, it includes: A printed circuit board substrate (3), including two relatively arranged surfaces, with electronic components arranged on one of the surfaces; and, A temperature deformation reinforcing layer, including at least two metal layers with different coefficients of thermal expansion, and at least two of the metal layers are stacked on top of each other; The other surface of the printed circuit board substrate (3) is attached to the temperature deformation reinforcing layer, and the bending deformation direction of the temperature deformation reinforcing layer is opposite to the deformation direction of the printed circuit board substrate (3); The temperature deformation reinforcing layer includes a first metal layer (1) and a second metal layer (2), and the coefficient of thermal expansion of the first metal layer (1) is greater than that of the second metal layer (2); A glue layer (4) is provided between the temperature deformation reinforcing layer and the printed circuit board substrate (3), and the temperature deformation reinforcing layer is pasted on the printed circuit board substrate (3) through the glue layer (4); The temperature deformation reinforcing layer includes an enlarged end (51) and a shrinking end (52), and the two enlarged ends (51) are arranged on both sides of the shrinking end (52), and the overall shape of the temperature deformation reinforcing layer is the same as the overall shape of the printed circuit board substrate (3).

2. The printed circuit board for reinforcing temperature deformation according to claim 1, characterized in that, The first metal layer (1) is arranged between the second metal layer (2) and the printed circuit board substrate (3), or the second metal layer (2) is arranged between the first metal layer (1) and the printed circuit board substrate (3).

3. The printed circuit board for reinforcing temperature deformation according to claim 2, characterized in that, The thickness of the first metal layer (1) is equal to the thickness of the second metal layer (2).

4. The printed circuit board for reinforcing temperature deformation according to claim 3, characterized in that, The thickness of the printed circuit board substrate (3) is 0.3 - 2 mm, and the thickness of the temperature deformation reinforcing layer is 0.15 - 2 mm.

5. The printed circuit board for reinforcing temperature deformation according to claim 4, characterized in that, The material of the first metal layer (1) is Ni22Cr3, and the material of the second metal layer (2) is Ni 36.

6. A camera module, characterized in that, it includes an imaging chip (6) and the printed circuit board for reinforcing temperature deformation according to any one of claims 1 to 5, and the imaging chip (6) is arranged on the printed circuit board for reinforcing temperature deformation and is located on the surface where the electronic components are arranged.

7. The camera module according to claim 6, characterized in that, A bracket (8) is arranged on the printed circuit board substrate (3), and a camera component (7) located above the imaging chip (6) and a voice coil motor (9) for driving the camera component (7) to move are installed on the bracket (8).

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