TW202404450A - Circuit board and heat spreader thereof - Google Patents

Abstract

A circuit board includes a substrate and a heat spreader which is attached to the substrate. The heat spreader includes a body portion and at least one stress release portion. The stress release portion is located between the body portion and a first edge of the heat spreader and includes a plurality of stress release holes. The shortest distance from an edge of an opening of each of the stress release holes to the first edge of the heat spreader is less than or equal to 6 mm. The stress release holes are provided to release an internal stress within the heat spreader so as to avoid the heat spreader from peeling from corner or edge of the substrate due to the internal stress.

Description

Circuit board and its heat sink

The present invention relates to a circuit board and its heat sink, in particular to a flexible and retractable circuit board and its heat sink.

Please refer to Figure 7. A conventional flexible circuit board 30 is used to electrically connect two electronic components (not shown in the figure, such as a panel and a circuit board). The flexible circuit board 30 has a substrate 31 and a heat sink. Chip 32. A chip 40 is disposed on a circuit layer (not shown) of the substrate 31. The heat sink 32 is attached to the substrate 31. Due to the thermal expansion coefficient, elasticity coefficient and density of the substrate 31 and the heat sink 32 Therefore, when the operating temperature of the flexible circuit board 30 rises, or when the flexible circuit board 30 needs to be bent, the heat sink will generate an internal stress, and the internal stress will cause the corners or corners of the heat sink 32 to bend. The edge peels off the substrate to form a gap G between the heat sink 32 and the substrate 31 , thereby affecting the heat dissipation performance of the heat sink 32 .

The main purpose of the present invention is to release the internal stress generated by a heat sink attached to a substrate due to operating temperature or when it is bent, so as to prevent the heat sink from peeling off the substrate, thereby affecting the heat dissipation performance of the heat sink.

A circuit board of the present invention includes a substrate and a heat sink. The substrate has a circuit layer. The heat sink is attached to the substrate with an adhesive layer. The heat sink has a first edge and a second edge. The heat sink The sheet includes a body part and at least one stress relief part, the stress relief part is located between the body part and the first edge, the stress relief part has a plurality of stress relief holes, each of the stress relief holes at least exposes the substrate or Each of the stress relief holes in one of the adhesive layers has an opening, and a minimum distance between an edge of the opening and the first edge is no more than 6 mm.

The present invention provides a heat sink for a circuit board, which has a first edge and a second edge. The heat sink is characterized in that the heat sink includes a body part and at least one stress relief part, and the stress relief part is located between the body part and the stress relief part. Between the first edges, the stress relief portion has a plurality of stress relief holes, each of the stress relief holes has an opening, and a minimum distance between an edge of the opening and the first edge is not greater than 6 mm.

The present invention uses the stress relief part located between the body part and the first edge and the stress relief holes provided in the stress relief part to release the heat sink caused by the change in the operating temperature of the circuit board. And the internal stress generated by the different shrinkage amounts of the heat sink, and/or the internal stress generated when the heat sink is bent, to prevent the heat sink from peeling off the substrate from corners or edges.

Please refer to Figures 1 and 2. A circuit board 10 of the present invention can be combined with a chip 20 to form a packaging structure (such as a chip-on-film package, COF). However, it is not limited to this. The circuit board 10 can be It is used to electrically connect two electronic components (not shown in the figure, such as a panel and another circuit board). The circuit board 10 includes a substrate 11 and a heat sink 12. The substrate 11 has a circuit layer (not shown in the figure). ), the chip 20 is bonded to the circuit layer, and the heat sink 12 is attached to one side of the substrate 11 with an adhesive layer 13 .

Please refer to Figures 1 and 3. The heat sink 12 has at least a first edge 12a and at least a second edge 12b. The substrate 11 has a pre-bent portion 11a. The second edge 12b of the heat sink 12 is projected onto The pre-bent part 11a, the heat sink 12 includes a body part 12c and at least one stress relief part 12d. The stress relief part 12d is located between the body part 12c and the first edge 12a. In this embodiment, the heat dissipation part 12d is located between the body part 12c and the first edge 12a. The sheet 12 includes two stress relief portions 12d, and each stress relief portion 12d is located on two sides of the main body portion 12c.

Please refer to Figures 2 and 3. The stress relief portion 12d has a plurality of stress relief holes 12e. Each of the stress relief holes 12e exposes at least one of the substrate 11 or the adhesive layer 13. In this embodiment, toward In the direction of the second edge 12b, the stress relief holes 12e are arranged in a straight line, or, please refer to Figure 4, in different embodiments, in the direction of the second edge 12b, the stress relief holes 12e are arranged in a curve. .

Please refer to Figures 3 and 4. The heat sink 12 has a surface 12h, and each stress relief hole 12e has an opening 12f. The openings 12f are located on the surface 12h, toward the second edge 12b, and two adjacent ones 12f. There is a distance D between the openings 12f, and the distance D is between 1 and 5 mm.

Please refer to Figures 3 and 4. In this embodiment, the apertures of the openings 12f are the same, and the apertures of the openings are between 0.4 and 1.2mm. The total area of the openings 12f occupies the area of the surface. 0.4% to 3.62%, or, please refer to Figure 5. In different embodiments, the apertures of the openings 12f are different, and the apertures of the openings are between 0.4 and 1.2mm.

Please refer to Figures 3 to 5. The minimum distance D1 between an edge 12g of the opening 12f and the first edge 12a is no more than 6mm. Preferably, the edge of the opening 12f closest to the second edge 12b A minimum distance D2 between 12g and the second edge 12b is no more than 5mm.

Please refer to Figures 1, 2 and 6. Since the thermal expansion coefficient, elasticity coefficient and density of the substrate 11 and the heat sink 12 are different, when the operating temperature of the flexible circuit board 10 rises, the substrate 11 and the heat sink 12 12 produces different shrinkage amounts, or when the flexible circuit board 10 is bent due to assembly requirements, causing the heat sink 12 to be bent, the stress relief holes 12e provided in the stress relief portion 12d are released. The heat sink 12 generates an internal stress due to the operating temperature change of the circuit board 10 or when it is bent, so as to prevent the heat sink 12 from peeling off the substrate 11 from a corner or an edge, causing the heat sink 12 to be in contact with the substrate 11 . A gap is formed between the substrates 11, thereby affecting the heat dissipation performance of the heat sink 12. In addition, when the circuit board 10 is rolled up or bent, the adhesive layer 13 can be squeezed into the stress relief hole 12e and bonded to the stress relief hole 12e. A hole wall 12i of each stress relief hole 12e is used to increase the adhesion of the heat sink 12 to the substrate 11 to prevent the heat sink 12 from peeling off the substrate 11.

The protection scope of the present invention shall be determined by the appended patent application scope. Any changes and modifications made by anyone familiar with this art without departing from the spirit and scope of the present invention shall fall within the protection scope of the present invention. .

10:Circuit board 11:Substrate 11a: Pre-bent part 12: Heat sink 12a: first edge 12b: second edge 12c: Body part 12d: Stress relief part 12e: Stress relief hole 12f: Opening 12g: edge 12h: surface 12i: hole wall 13: adhesive layer 20:Chip 30:Flexible circuit board 31:Substrate 32:Heat sink 40:wafer D:pitch D1: Spacing D2: Spacing G: Gap

Figure 1: Bottom view of the circuit board of the present invention. Figure 2: Cross-sectional view of the circuit board of the present invention. Figure 3: Bottom view of the heat sink of the present invention. Figure 4: Bottom view of the heat sink of the present invention. Figure 5: Bottom view of the heat sink of the present invention. Figure 6: Cross-sectional view of the circuit board of the present invention. Figure 7: A cross-sectional view of a conventional circuit board.

12:Heat sink

12a: first edge

12b: Second edge

12c: Body part

12d: Stress relief part

12e: Stress relief hole

12f:Open your mouth

12g: edge

12h: Surface

D: spacing

D1: spacing

D2: Spacing

Claims (18)

A circuit board containing: a substrate having a circuit layer; and A heat sink is attached to the substrate with an adhesive layer. The heat sink has a first edge and a second edge. The heat sink includes a body part and at least one stress relief part. The stress relief part is located on the body part. Between the first edge and the first edge, the stress relief portion has a plurality of stress relief holes. Each stress relief hole exposes at least one of the substrate or the adhesive layer. Each stress relief hole has an opening, and an opening of the opening. A minimum distance between the edge and the first edge is no more than 6 mm. The circuit board of claim 1, wherein the stress relief holes are arranged in a straight line toward the second edge direction. The circuit board of claim 1, wherein the stress relief holes are arranged in a curve toward the second edge direction. The circuit board of claim 1, wherein a minimum distance between the edge of the opening closest to the second edge and the second edge is no more than 5 mm. The circuit board of claim 1, wherein the heat sink has a surface, the openings are located on the surface, and the total area of the openings accounts for 0.4% to 3.62% of the area of the surface. Such as the circuit board of claim 1, wherein the hole diameter of each opening is the same, and the hole diameter of each opening is between 0.4 and 1.2 mm. For example, the circuit board of claim 1, wherein the hole diameter of each opening is different, and the hole diameter of each opening is between 0.4 and 1.2 mm. The circuit board of claim 1, wherein there is a distance between two adjacent openings toward the second edge direction, and the distance is between 1 and 5 mm. The circuit board of claim 1, wherein the substrate has a pre-bent portion, and the second edge of the heat sink is projected onto the pre-bent portion. Such as the circuit board of claim 1 or 9, wherein the adhesive layer is squeezed into the stress relief hole and adhered to a hole wall of each stress relief hole. A heat sink for a circuit board, which has a first edge and a second edge, characterized in that: the heat sink includes a body part and at least one stress relief part, and the stress relief part is located between the body part and the first edge The stress relief part has a plurality of stress relief holes, each stress relief hole has an opening, and a minimum distance between an edge of the opening and the first edge is not greater than 6 mm. The heat sink of the circuit board of claim 11, wherein the stress relief holes are arranged in a straight line toward the second edge direction. The heat sink of the circuit board of claim 11, wherein the stress relief holes are arranged in a curve toward the second edge direction. The heat sink of the circuit board of claim 11, wherein a minimum distance between the edge of the opening closest to the second edge and the second edge is no more than 5 mm. The heat sink of the circuit board of claim 11, wherein the heat sink has a surface, each of the openings is located on the surface, and the total area of the openings of the stress relief holes accounts for 0.4% to 3.62% of the area of the surface. . For example, the heat sink of the circuit board of claim 11, wherein the hole diameter of each opening is the same, and the hole diameter of each opening is between 0.4 and 1.2 mm. For example, in the heat sink of the circuit board of claim 11, the apertures of the openings are different, and the apertures of the openings are between 0.4 and 1.2 mm. The heat sink of the circuit board of claim 11, wherein toward the second edge direction, there is a distance between two adjacent openings, and the distance is between 1 and 5 mm.

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