TWI854645B - Heat dissipating sheet and chip on film package structure - Google Patents

Abstract

A heat dissipating sheet is adapted to be disposed on a flexible circuit board. The flexible circuit board has a surface and a chip mounting area defined on the surface. The heat dissipating sheet is disposed on the surface of the flexible circuit board and corresponds to the chip mounting area. The chip mounting area has two opposite long sides and two opposite short sides. The heat dissipating sheet includes a heat dissipating layer and an insulating protection layer. The insulating protection layer is disposed on the heat dissipating layer. At least one of two sides of the heat dissipating sheet corresponding to the two opposite long sides has recessed portion(s), and the recessed portion is formed on at least one of the heat dissipating layer and the insulating protection layer.

Description

Heat sink and Chip-on-Film package structure

The present invention relates to a patch and a packaging structure, and in particular to a heat dissipation patch and a film flip chip packaging structure using the heat dissipation patch.

In order to improve the heat dissipation effect, the current chip on film (COF) usually attaches a heat sink to the surface of the COF structure, especially at the location of the chip corresponding to the main heat source, so as to increase the heat dissipation area and achieve a better heat dissipation effect. However, when the heat sink is attached to the chip surface of the COF structure, the thickness of the chip causes the heat sink to stretch and generate stress, especially at the long side of the chip. If the distance between the edge of the heat sink and the chip is short and insufficient to evenly dissipate the continuous stress accumulated at the corresponding long side of the chip, the heat sink cannot be smoothly attached to the film flip chip package structure, and wrinkles or waves are likely to form at the edge of the heat sink, thereby affecting the reliability, appearance specifications and heat dissipation effect of the product.

The present invention provides a heat sink patch, which can reduce or avoid the problem in the prior art that the heat sink patch cannot be evenly attached to the film chip package structure and wrinkles/waves are generated on the edge of the heat sink patch.

The present invention also provides a thin film chip package structure, which includes the above-mentioned heat sink patch and can have better product reliability and heat dissipation efficiency.

The heat sink patch of the present invention is used to be configured on a flexible circuit carrier. The flexible circuit carrier has a surface and a chip setting area defined on the surface. The heat sink patch is configured on the surface of the flexible circuit carrier and corresponds to the chip setting area. The chip setting area has two opposite long sides and two opposite short sides. The heat sink patch includes a heat sink layer and an insulating protective layer. The insulating protective layer is arranged on the heat sink layer. At least one of the two side edges of the heat sink patch corresponding to the two long edges has an inner recess, and the inner recess is formed in at least one of the heat sink layer and the insulating protective layer.

The film flip chip packaging structure of the present invention includes a flexible circuit carrier, a chip and a heat sink. The flexible circuit carrier has a surface and a chip setting area defined on the surface. The chip setting area has two opposite long sides and two opposite short sides. The chip is arranged in the chip setting area and is electrically connected to the flexible circuit carrier. The heat sink is arranged on the surface of the flexible circuit carrier. The heat sink corresponds to the chip setting area and covers the chip. The heat sink includes a heat sink layer and an insulating protective layer. The insulating protective layer is arranged on the heat sink layer. At least one of the two side edges of the heat dissipation patch corresponding to the two long edges has a concave portion, and the concave portion is formed in at least one of the heat dissipation layer and the insulating protection layer.

Based on the above, in the design of the heat sink of the present invention, at least one of the two side edges of the two long sides of the chip setting area of the heat sink has an inner recess, and the inner recess is formed in at least one of the heat sink layer and the insulating protective layer. When the heat sink is attached to the flexible circuit carrier, the continuous stress generated by the thickness of the chip on the heat sink in the direction parallel to the long side of the chip can be blocked and weakened by these inner recesses, thereby avoiding the heat sink from generating wrinkles or wavy lines at the edges that do not meet the appearance specifications. Therefore, the film flip chip packaging structure using the heat sink of the present invention can have better product reliability and heat dissipation efficiency.

In order to make the above features and advantages of the present invention more clearly understood, embodiments are specifically described below in detail with reference to the accompanying drawings.

The present invention is more fully described with reference to the drawings of the present embodiment. However, the present invention can also be embodied in various different forms and should not be limited to the embodiments described herein. The thickness, size or size of the layers or regions in the drawings may be exaggerated for clarity.

It should be noted that the chip-on-film packaging structure shown in the following figure is operated in a reel-to-reel transmission manner. Although the heat sink in the following figure is only schematically shown as being applied to a packaging unit on the reel that forms the chip-on-film packaging structure, the present invention is not limited to this. The heat sink in the following figure can be applied to multiple packaging units on the reel at the same time.

FIG. 1A is a schematic top view of a thin film chip package structure according to an embodiment of the present invention. FIG. 1B is a schematic three-dimensional view of the heat sink in FIG. 1A. FIG. 1C is a schematic cross-sectional view of FIG. 1A. FIG. 1A omits some components, and the omitted parts can be understood by referring to the schematic cross-sectional view of FIG. 1C.

Please refer to FIG. 1A and FIG. 1C at the same time. In this embodiment, the thin film flip chip package structure 100a includes a flexible circuit carrier 110, a chip 120 and a heat sink 130a. The flexible circuit carrier 110 has a surface 112 and a chip setting area 114 defined on the surface 112. The chip setting area 114 has two opposite long sides 115 and two opposite short sides 117. The chip 120 is arranged in the chip setting area 114 and is electrically connected to the flexible circuit carrier 110. The heat sink 130a is arranged on the surface 112 of the flexible circuit carrier 110. The heat sink 130a corresponds to the chip setting area 114 and covers the chip 120. The heat sink patch 130a includes a heat sink layer 132a and an insulating protective layer 134a. The insulating protective layer 134a is disposed on the heat sink layer 132a. The heat sink patch 130a has a concave portion C1 on one of the two side sides S1 and S2 corresponding to the two long sides 115, and the concave portion C1 is formed in at least one of the heat sink layer 132a and the insulating protective layer 134a. In this embodiment, the concave portion C1 is formed in the insulating protective layer 134a. In addition, the number of the concave portions C1 on one side S1 of the heat sink patch 130a is at least two, and they correspond to the two short sides 117 of the chip setting area 114 respectively. In this embodiment, the number of the concave portions C1 on the side S1 is four, and two of the concave portions C1 correspond to the two short sides 117 of the chip placement area 114. However, the present invention does not limit the number of concave portions on one side.

Specifically, the chip 120 may be configured in the chip setting area 114 in a flip-chip manner and electrically connected to the flexible circuit carrier 110. Here, the flexible circuit carrier 110 may include a flexible substrate 111, a plurality of pins 113, and a solder mask 119. The material of the flexible substrate 111 is, for example, polyimide (PI), polyethylene terephthalate (PET), polyethersulfone (PES), polycarbonate (PC), or other suitable flexible materials. The plurality of pins 113 are disposed on the surface 111a of the flexible substrate 111. The solder mask 119 is disposed on the surface 111a of the flexible substrate 111 and is located outside the chip placement area 114 and partially covers the plurality of pins 113 to prevent the plurality of pins 113 from being oxidized or short-circuited due to foreign matter contamination. The portion of the plurality of pins 113 exposed by the solder mask 119 can be used for electrical connection with the chip 120 or external components. The material of the solder mask 119 is, for example, green paint, which is not limited here.

In one embodiment, the chip-on-film package structure 100a further includes a filling glue layer 140, wherein the filling glue layer 140 can be filled between the flexible substrate 111 and the chip 120 to prevent moisture or foreign matter from invading and causing electrical contact damage or electrical abnormality. The filling glue layer 140 is, for example, underfill glue, but is not limited thereto.

Please refer to FIG. 1B and FIG. 1C , the heat sink patch 130a of this embodiment is disposed on the surface 112 of the flexible circuit carrier 110 and corresponds to the chip setting area 114. Here, the heat sink patch 130a further includes a first adhesive layer 136a and a second adhesive layer 138a. The first adhesive layer 136a is disposed between the insulating protection layer 134a and the first surface 131a of the heat sink layer 132a, wherein the insulating protection layer 134a is attached to the heat sink layer 132a through the first adhesive layer 136a. The second adhesive layer 138a is disposed on the second surface 133a of the heat dissipation layer 132a opposite to the first surface 131a, wherein the heat dissipation patch 130a can be attached to the surface 112 of the flexible circuit carrier 110 and cover the chip 120 through the second adhesive layer 138a to directly help the chip 120 to dissipate heat.

As shown in FIG. 1B and FIG. 1C , the size of the insulating protection layer 134a is larger than the size of the heat dissipation layer 132a, and the insulating protection layer 134a completely covers the heat dissipation layer 132a. In other words, the orthographic projection of the heat dissipation layer 132a on the flexible circuit carrier 110 is completely located within the orthographic projection of the insulating protection layer 134a on the flexible circuit carrier 110, so as to achieve the protection effect on the heat dissipation layer 132a. In this embodiment, the size of the first adhesive layer 136a is substantially the same as that of the heat dissipation layer 132a. Therefore, when the heat dissipation patch 130a is disposed on the flexible circuit carrier 110, the outer edge of the insulating protection layer 134a that exceeds the heat dissipation layer 132a is not attached with the adhesive layer and naturally hangs or is suspended. Here, the material of the heat dissipation layer 132a may include metal foil or graphite film, wherein the metal foil is, for example, aluminum foil or copper foil, but the present invention is not limited thereto. The insulating protection layer 134a is made of a flexible material such as polyimide (PI) to protect the heat dissipation layer 132a and prevent the heat dissipation layer 132a from being scratched or damaged, but the present invention is not limited thereto.

Please refer to FIG. 1A again. The heat sink 130a is disposed on the flexible circuit carrier 110 and covers a larger area than the chip setting area 114 and completely covers the chip setting area 114. In a top view, the shape of the multiple concave portions C1 on the side S1 of the heat sink 130a is, for example, an arc shape, but is not limited thereto. The horizontal distance H in the direction perpendicular to the side S1 from the side S1 having the concave portion C1 to a point of the concave portion C1 farthest from the side S1 is, for example, between 0.1 mm and 5 mm. In addition, the sum of the distances L of the concave portions C1 on the parallel side S1 is not less than 1/6 of the length of the side S1.

Since the heat sink 130a of the present embodiment has a concave portion C1 on the side S1 corresponding to a long side 115 of the chip placement area 114, when the heat sink 130a is attached to the flexible circuit carrier 110, the continuous stress generated by the thickness of the chip 120 on the heat sink 130a in the direction parallel to the long side 115 can be blocked and weakened by these concave portions C1, thereby avoiding the heat sink 130a from generating wrinkles or ripples at the edge (i.e., the side S1). Therefore, the film flip chip package structure 100a using this heat sink 130a can have better product reliability and heat dissipation efficiency.

It should be noted that the following embodiments use the component numbers and some contents of the previous embodiments, wherein the same number is used to represent the same or similar components, and the description of the same technical contents is omitted. The description of the omitted parts can refer to the previous embodiments, and the following embodiments will not be repeated.

FIG2 is a three-dimensional schematic diagram of a heat sink according to another embodiment of the present invention. Please refer to FIG1B and FIG2 simultaneously. The heat sink 130b of this embodiment is similar to the heat sink 130a described above. The difference between the two is that in this embodiment, the inner concave portion C2 of the heat sink 130b is formed on the combination of the heat sink layer 132b, the first adhesive layer 136b and the second adhesive layer 138b. That is, the inner concave portion C2 is not formed on the insulating protective layer 134b.

FIG3 is a three-dimensional schematic diagram of a heat sink according to another embodiment of the present invention. Please refer to FIG1B and FIG3 simultaneously. The heat sink 130c of this embodiment is similar to the heat sink 130a described above. The difference between the two is that in this embodiment, the inner concave portion C3 of the heat sink 130c is formed on the heat sink layer 132c, the first adhesive layer 136c, the second adhesive layer 138c and the insulating protective layer 134c.

In short, the concave portion C1 of the heat sink patch 130a may be formed on the insulating protective layer 134a; or, the concave portion C2 of the heat sink patch 130b may be formed on the combination of the heat sink layer 132b, the first adhesive layer 136b and the second adhesive layer 138b; or, the concave portion C3 of the heat sink patch 130c may be formed on the heat sink layer 132c, the first adhesive layer 136c, the second adhesive layer 138c and the insulating protective layer 134c. In other words, as long as the concave portion of the heat sink patch is formed on at least one of the heat sink layer and the insulating protective layer, it is within the scope of protection of the present invention.

In addition, in the plan view, the inner concave portion C1 is in an arc shape and is only formed on one side S1 of the heat sink 130a, 130b, 130c, but the present invention is not limited thereto.

FIG4 is a three-dimensional schematic diagram of a heat sink according to another embodiment of the present invention. Please refer to FIG2 and FIG4 simultaneously. The heat sink 130d of this embodiment is similar to the heat sink 130b described above. The difference between the two is that in this embodiment, the shape of the inner concave portion C4 of the heat sink 130d is, for example, a rectangle when viewed from above. The inner concave portion C4 of the heat sink 130d is formed on the combination of the heat sink layer 132d, the first adhesive layer 136d, and the second adhesive layer 138d. However, in other embodiments, the inner concave portion C4 may be formed only on the insulating protective layer 134d or on the heat dissipation layer 132d, the first adhesive layer 136d, the second adhesive layer 138d and the insulating protective layer 134d. In another embodiment, the shape of the inner concave portion of the heat dissipation patch is sawtooth or other appropriate shapes when viewed from above.

FIG5 is a schematic top view of a chip-on-film package structure according to another embodiment of the present invention. Please refer to FIG1A and FIG5 simultaneously. The chip-on-film package structure 100b of this embodiment is similar to the chip-on-film package structure 100a described above. The difference between the two is that: in this embodiment, from a top view, the two sides S1 and S2 of the heat sink 130e respectively have a concave portion C5 corresponding to the long side 115 of the chip setting area 114, wherein the shape of the concave portion C5 is, for example, an arc shape, but not limited thereto. In another embodiment, the number of the concave portions C5 of the two sides S1 and S2 of the heat sink 130e may be inconsistent, but the number of the concave portions C5 of a single side S1 and S2 is at least one, preferably, a plurality of. In this embodiment, the positions of the inner concave portions C5 of the two side edges S1 and S2 of the heat sink 130e are symmetrical. However, in another embodiment, the positions of the inner concave portions C5 of the two side edges S1 and S2 of the heat sink 130e may also be asymmetrical.

In summary, in the design of the heat sink of the present invention, at least one of the two side edges of the two long sides of the chip placement area of the heat sink has an inner recess, and the inner recess is formed in at least one of the heat sink layer and the insulating protective layer. When the heat sink is attached to the flexible circuit carrier, the continuous stress generated by the thickness of the chip on the heat sink in the direction parallel to the long side of the chip can be blocked and weakened by these inner recesses, thereby avoiding the heat sink from generating wrinkles or wavy lines at the edges that do not meet the appearance specifications. Therefore, the film flip chip packaging structure using the heat sink of the present invention can have better product reliability and heat dissipation efficiency.

Although the present invention has been disclosed as above by the embodiments, they are not intended to limit the present invention. Any person with ordinary knowledge in the relevant technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be defined by the scope of the attached patent application.

100a, 100b: film flip chip package structure 110: flexible circuit carrier 111: flexible substrate 111a: surface 112: surface 113: pins 114: chip setting area 115: long side 117: short side 119: solder mask 120: chip 130a, 130b, 130c, 130d, 130e: heat sink 131a: first surface 132a, 132b, 132c, 132d: heat sink 133a: second surface 134a, 134b, 134c, 134d: insulation protection layer 136a, 136b, 136c, 136d: first adhesive layer 138a, 138b, 138c, 138d: second adhesive layer 140: filling adhesive layer C1, C2, C3, C4, C5: concave part H: horizontal distance L: distance S1, S2: side

FIG. 1A is a schematic top view of a chip-on-film package structure according to an embodiment of the present invention. FIG. 1B is a schematic three-dimensional view of the heat sink in FIG. 1A. FIG. 1C is a schematic cross-sectional view of FIG. 1A. FIG. 2 is a schematic three-dimensional view of a heat sink according to another embodiment of the present invention. FIG. 3 is a schematic three-dimensional view of a heat sink according to another embodiment of the present invention. FIG. 4 is a schematic three-dimensional view of a heat sink according to another embodiment of the present invention. FIG. 5 is a schematic top view of a chip-on-film package structure according to another embodiment of the present invention.

100a: Thin film chip packaging structure

110: Flexible circuit board

112: Surface

114: Chip setting area

115: Long side

117: Short side

120: Chip

130a: Heat sink

132a: Heat dissipation layer

134a: Insulation protective layer

140: Filling glue layer

C1: Concave part

H: horizontal distance

L: Distance

S1, S2: Side

Claims (12)

A heat sink is used to be arranged on a flexible circuit carrier. The flexible circuit carrier has a surface and a chip setting area defined on the surface. The heat sink is arranged on the surface of the flexible circuit carrier and corresponds to the chip setting area. The chip setting area has two opposite long sides and two opposite short sides. The heat sink includes: a heat sink layer; and an insulation layer. The heat dissipation patch has a concave portion on at least one of the two side edges corresponding to the two long sides, and the concave portion is formed on at least one of the heat dissipation layer and the insulating protective layer, and the heat dissipation patch has a horizontal distance from the side edge having the concave portion to a point of the concave portion farthest from the side edge in a direction perpendicular to the side edge. The heat sink as described in claim 1, wherein the number of the inner recesses on one side of the heat sink is at least two, and they correspond to the two short sides of the chip setting area respectively. The heat sink patch as described in claim 1 further comprises: a first adhesive layer disposed between the insulating protective layer and the first surface of the heat sink layer, the insulating protective layer being attached to the heat sink layer through the first adhesive layer; and a second adhesive layer disposed on the second surface of the heat sink layer opposite to the first surface; wherein the inner concave portion of the heat sink patch is formed on at least one of the combination of the heat sink layer, the first adhesive layer and the second adhesive layer and the insulating protective layer. The heat sink as described in claim 1, wherein the heat sink is disposed on the flexible circuit carrier and covers a larger area than the chip setting area and completely covers the chip setting area. A heat sink patch as described in claim 1, wherein the size of the insulating protective layer is larger than the size of the heat sink layer, and the insulating protective layer completely covers the heat sink layer. As described in claim 1, the heat sink, when viewed from above, has a shape of an arc, a sawtooth or a rectangle. A film flip chip package structure includes: a flexible circuit carrier having a surface and a chip setting area defined on the surface, the chip setting area having two opposite long sides and two opposite short sides; a chip, arranged in the chip setting area and electrically connected to the flexible circuit carrier; and a heat sink, arranged on the surface of the flexible circuit carrier, the heat sink corresponding to the chip setting area and covering the chip. , the heat sink patch includes: a heat sink layer, and; an insulating protective layer, disposed on the heat sink layer; wherein the heat sink patch has a concave portion on at least one of the two side edges corresponding to the two long sides, the concave portion is formed on at least one of the heat sink layer and the insulating protective layer, and the heat sink patch has a horizontal distance from the side edge having the concave portion to a point of the concave portion farthest from the side edge in a direction perpendicular to the side edge. The chip-on-film package structure as described in claim 7, wherein the number of the inner recesses on one side of the heat sink is at least two, and they correspond to the two short sides of the chip placement area respectively. The chip-on-film package structure as described in claim 7, wherein the heat sink further comprises: a first adhesive layer disposed between the insulating protective layer and the first surface of the heat sink, the insulating protective layer being attached to the heat sink through the first adhesive layer; and a second adhesive layer disposed on the second surface of the heat sink opposite to the first surface; wherein the inner concave portion of the heat sink is formed on at least one of the combination of the heat sink, the first adhesive layer and the second adhesive layer and the insulating protective layer. A film flip chip package structure as described in claim 7, wherein the heat sink is arranged on the flexible circuit carrier and covers a larger area than the chip setting area and completely covers the chip setting area. A chip-on-film package structure as described in claim 7, wherein the size of the insulating protective layer is larger than the size of the heat dissipation layer, and the insulating protective layer completely covers the heat dissipation layer. The thin film chip package structure as described in claim 7, wherein the shape of the inner concave portion includes arc shape, sawtooth shape or rectangle when viewed from top.

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