Device substrate

This application claims the priority benefit of Taiwan application serial no. 108135045, filed on Sep. 27, 2019. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

The disclosure relates to a device substrate, and in particular, to a device substrate including bonding pads and leads.

Chip on film (COF) is a technology for packaging a chip on a flexible printed circuit (FPC) board through flip chip bonding. Currently, a chip is bonded to leads on a flexible substrate circuit mainly through thermal compression bonding.

The COF exhibits light, thin, and flexible characteristics. Therefore, a drive chip for a high-end display device usually uses the COF technology. Generally, the COF is bonded to a substrate of the display device through press fitting. However, when the COF is press-fitted to the substrate of the display device, a film layer on the substrate may be easily deformed due to pressure and temperature.

The disclosure provides a device substrate, which is not easily deformed in a press-fitting process of first bonding pads and first leads.

At least one embodiment of the disclosure provides a device substrate. The device substrate includes a first substrate, a second substrate, a plurality of bonding pads, and a plurality of connection ends. The second substrate faces the first substrate. The plurality of bonding pads are separated from each other and located on the first substrate, and include a plurality of first bonding pads and a plurality of second bonding pads. The first bonding pads are arranged in a first column. The second bonding pads are arranged in a second column. The connection ends are located on the second substrate, and include a plurality of first leads and a plurality of second leads. The plurality of first leads and the plurality of second leads respectively overlap the first bonding pads and the second bonding pads. The first lead includes a first extension portion and a first branch portion. The first extension portion overlaps the corresponding first bonding pad, and extends from the first column to the second column. The first branch portion is connected to an end of the first extension portion close to the second column, and forms an angle with the first extension portion.

FIG. 1A is a schematic top view of a device substrate according to an embodiment of the disclosure.

FIG. 1B is a schematic diagram of a cross section along a line aa′ in FIG. 1A .

FIG. 1C is a schematic top view of a device substrate according to an embodiment of the disclosure.

FIG. 2 is a schematic top view of a device substrate according to an embodiment of the disclosure.

FIG. 3 is a schematic top view of a device substrate according to an embodiment of the disclosure.

FIG. 1A is a schematic top view of a device substrate according to an embodiment of the disclosure. FIG. 1B is a schematic diagram of a cross section along a line aa′ in FIG. 1A . FIG. 1C is a schematic top view of a device substrate according to an embodiment of the disclosure. For ease of description, FIG. 1A shows a first substrate, a second substrate, a chip, and bonding pads, and omits other components. For ease of description, FIG. 1C shows bonding pads and connection ends, and omits other components.

Referring to FIG. 1A , FIG. 1B , and FIG. 1C , a device substrate 10 includes a first substrate 100 , a second substrate 200 , a plurality of bonding pads P, and a plurality of connection ends L.

In the present embodiment, the first substrate 100 includes an active area AA and a border area BA. The border area BA is located on at least one side of the active area AA. In some embodiments, the device substrate 10 is a display device, and the active area AA is a display area, but the disclosure is not limited thereto.

The first substrate 100 may be made of glass, an organic polymer, or other suitable materials. In the present embodiment, the first substrate 100 may be a flexible substrate made of polyimide (PI). In the present embodiment, the first substrate 100 is connected to a carrier substrate BF by using an adhesive material PSA 1 , and the carrier substrate BF may be connected to another component, for example, a metal plate, a plastic substrate, or a housing, by using an adhesive material PSA 2 , but the disclosure is not limited thereto.

The bonding pads P are separated from each other and located in the border area BA of the first substrate 100 . In the present embodiment, the bonding pads P include first bonding pads 112 , second bonding pads 114 , third bonding pads 116 , and fourth bonding pads 118 . The first bonding pads 112 , the second bonding pads 114 , the third bonding pads 116 , and the fourth bonding pads 118 are electrically connected to corresponding conducting wires 120 . The conducting wires 120 extend from the border area BA to the active area AA.

In the present embodiment, the first bonding pads 112 , the second bonding pads 114 , the third bonding pads 116 , and the fourth bonding pads 118 belong to a same film layer, and the conducting wires 120 belong to another film layer different from that of the first bonding pads 112 , the second bonding pads 114 , the third bonding pads 116 , and the fourth bonding pads 118 .

In the present embodiment, an insulation layer 130 is located on the first substrate 100 , and located between the conducting wires 120 and the first bonding pads 112 and between the conducting wires 120 and the second bonding pads 114 . The insulation layer 130 has a plurality of holes H, and the first bonding pads 112 and the second bonding pads 114 are electrically connected to the corresponding conducting wires 120 through the holes H.

The first bonding pads 112 are arranged in a first column 110 A, and the second bonding pads 114 are arranged in a second column 110 B. In the present embodiment, the first bonding pads 112 and the third bonding pads 116 are arranged in the first column 110 A, and the second bonding pads 114 and the fourth bonding pads 118 are arranged in the second column 110 B. In the present embodiment, an end of each first bonding pad 112 facing the second column 110 B is aligned with an end of each third bonding pad 116 facing the second column 110 B, and an end of each second bonding pad 114 facing the first column 110 A is aligned with an end of each fourth bonding pad 118 facing the first column 110 A.

In the present embodiment, the first bonding pads 112 and the third bonding pads 116 have a same extension direction E 1 , and the second bonding pads 114 and the fourth bonding pads 118 have a same extension direction E 2 . In the present embodiment, the extension direction E 1 is parallel to the extension direction E 2 . In the present embodiment, the first bonding pads 112 are aligned with the second bonding pads 114 in the extension direction E 1 of (or the extension direction E 2 ), and the third bonding pads 116 are aligned with the fourth bonding pads 118 in the extension direction E 1 of (or the extension direction E 2 ).

The second substrate 200 faces the first substrate 100 . A plurality of connection ends L, a plurality of cables 220 , and a chip 230 are located on the second substrate 200 . The connection ends L include a plurality of first leads 212 , a plurality of second leads 214 , a plurality of third leads 216 , and a plurality of fourth leads 218 . The chip 230 is electrically connected to the plurality of cables 220 by using a plurality of conductive bumps 232 , and respectively electrically connected to the first leads 212 , the second leads 214 , the third leads 216 , and the fourth leads 218 by using the plurality of cables 220 .

In the present embodiment, the chip 230 is located on a first surface 202 of the second substrate 200 , and the first leads 212 , the second leads 214 , the third leads 216 , and the fourth leads 218 are located on a second surface 204 of the second substrate 200 . The first surface 202 is opposite to the second surface 204 . In the present embodiment, some cables 220 are located on the first surface 202 , and some cables 220 are located on the second surface 204 . The cables 220 located on the first surface 202 are electrically connected to the cables 220 located on the second surface 204 via through holes 206 . The through holes 206 penetrate at least the second substrate 200 . In the present embodiment, a protective layer 242 and a protective layer 244 are respectively located on the first surface 202 and the second surface 204 of the second substrate 200 , and cover some cables 220 .

In the present embodiment, the chip 230 is packaged on the second substrate 200 by using a COF technology.

Pressure is exerted to the first leads 212 , the second leads 214 , the third leads 216 , and the fourth leads 218 , so that the first leads 212 , the second leads 214 , the third leads 216 , and the fourth leads 218 respectively overlap and are electrically connected to the first bonding pads 112 , the second bonding pads 114 , the third bonding pads 116 , and the fourth bonding pads 118 . In the present embodiment, a conducting material 300 is located between the bonding pads P and the connection ends L. In the present embodiment, the conducting material 300 is an anisotropic conductive film (ACF), and the conducting material 300 includes resin and conductive particles.

The first lead 212 includes a first extension portion 2122 and a first branch portion 2124 . The first extension portion 2122 overlaps a corresponding first bonding pad 112 , and extends from the first column 110 A to the second column 110 B. The first branch portion 2124 is connected to an end 2122 a of the first extension portion 2122 close to the second column 110 B, and forms an angle α with the first extension portion 2122 .

In the present embodiment, the first lead 212 further includes a first divergent portion 2126 . The first divergent portion 2126 is connected to the end 2122 a of the first extension portion 2122 close to the second column 110 B, and forms an angle β with the first branch portion 2124 . In the present embodiment, the angle β between the first branch portion 2124 and the first divergent portion 2126 is 10 degrees to 180 degrees. As the first branch portion 2124 and the first divergent portion 2126 are disposed, stress between the first bonding pad 112 and the second bonding pad 114 may be dispersed, so that the device substrate 10 is not easily deformed in a press-fitting process.

The second lead 214 includes a second extension portion 2142 . The second extension portion 2142 overlaps a corresponding second bonding pad 114 , and extends from the second column 110 B to the first column 110 A.

The third lead 216 includes a third extension portion 2162 . The third extension portion 2162 overlaps a corresponding third bonding pad 116 , and extends from the first column 110 A to the second column 110 B.

The fourth lead 218 includes a fourth extension portion 2182 and a fourth branch portion 2184 . The fourth extension portion 2182 overlaps a corresponding fourth bonding pad 118 , and extends from the second column 110 B to the first column 110 A. The fourth branch portion 2184 is connected to an end 2182 a of the fourth extension portion 2182 close to the first column 110 A, and forms an angle γ with the fourth extension portion 2182 .

In the present embodiment, the fourth lead 218 further includes a fourth divergent portion 2186 . The fourth divergent portion 2186 is connected to the end 2182 a of the fourth extension portion 2182 close to the first column 110 A, and forms an angle δ with the fourth branch portion 2184 . In the present embodiment, the angle δ between the fourth branch portion 2184 and the fourth divergent portion 2186 is 10 degrees to 180 degrees. As the fourth branch portion 2184 and the first fourth portion 2186 are disposed, stress between the third bonding pad 116 and the fourth bonding pad 118 may be dispersed, so that the device substrate 10 is not easily deformed in the press-fitting process.

In the present embodiment, a minimum spacing between two adjacent connection ends L is greater than 4 micrometers and less than 80 micrometers. This may resolve a problem of stress concentration in the press-fitting process and avoid short-circuiting of adjacent leads. When the minimum spacing between two adjacent connection ends L is greater than 80 micrometers, a gap between adjacent connection ends L is easily deformed in the press-fitting process. If utilization of cabling space is considered, a spacing between two adjacent connection ends L is greater than 10 micrometers and less than 30 micrometers, or is greater than 10 micrometers and less than 20 micrometers.

In the present embodiment, widths of the first extension portion 2122 , the second extension portion 2142 , the third extension portion 2162 , and the fourth extension portion 2182 range from 6 micrometers to PD-4 micrometers, where PD is a spacing between two adjacent extension portions in a same column (for example, the first column 110 A or the second column 110 B).

In the present embodiment, a gap GP is present between the first column 110 A and second column 110 B. In the present embodiment, a length L 1 of the first lead 212 overlapping the gap GP is different from a length L 3 of the third lead 216 overlapping the gap GP, and a length L 2 of the second lead 214 overlapping the gap GP is different from a length L 4 of the fourth lead 218 overlapping the gap GP. In the present embodiment, the length L 1 of the first lead 212 overlapping the gap GP is greater than the length L 3 of the third lead 216 overlapping the gap GP, and the length L 4 of the fourth lead 218 overlapping the gap GP is greater than the length L 2 of the second lead 214 overlapping the gap GP. An interval W 1 between the first lead 212 and the second lead 214 is staggered with an interval W 2 between the third lead 216 and the fourth lead 218 . In other words, the end 2122 a of the first extension portion 2122 close to the second column 110 B is staggered with the end 2182 a of the fourth extension portion 2182 close to the first column 110 A. This may evenly disperse weak points where stress concentrates, and avoid deformation of the device substrate 10 in the press-fitting process.

In the present embodiment, a sum of the length L 1 and the length L 3 is equal to a sum of the length L 2 and the length L 4 . This may evenly distribute pressure exerted in the press-fitting process.

In the present embodiment, the gap GP includes a first region R 1 , a second region R 2 , and a third region R 3 that have a same area and are connected in sequence. The first region R 1 is located between the first column 110 A and the second region R 2 . The third region R 3 is located between the second column 110 B and the second region R 2 . An area of the connection end L overlapping the first region R 1 is B′, an area of the connection end L overlapping the second region R 2 is A, and an area of the connection end L overlapping the third region R 3 is B. The area B and the area B′ may be the same or different. In the present embodiment, 1<A/B<1.93. This may better disperse stress in the press-fitting process, and improve the utilization of the cabling space. In some embodiments, 1<A/B′<1.93.

In the present embodiment, areas of all the first region R 1 , the second region R 2 , and the third region R 3 are AR, and 0.15≤(A+B+B′)3AR<1/3.

Based on the above, the first lead 212 of the device substrate 10 includes the first extension portion 2122 and the first branch portion 2124 , and an angle is present between the first branch portion 2124 and the first extension portion 2122 . Therefore, a problem of deformation in a region between the first bonding pads 112 and the second bonding pads 114 in a press-fitting process of the first bonding pads 112 on the first substrate 100 and the first leads 212 on the second substrate 200 of the device substrate 10 may be resolved, and a desired effect may be achieved in this design range.

FIG. 2 is a schematic top view of a device substrate according to an embodiment of the disclosure. It should be noted herein that, the embodiment of FIG. 2 follows reference numerals of components and some content in the embodiment of FIG. 1A to FIG. 1C , where the same or similar reference numerals are used to represent the same or similar components and the descriptions of the same technical content are omitted. For the explanation of the omitted part, reference may be made to the preceding embodiment and the descriptions thereof are omitted herein.

A main difference between a device substrate 20 in FIG. 2 and the device substrate 10 in FIG. 1C is as follows: Shapes of a first lead 212 and a fourth lead 218 of the device substrate 20 are different from shapes of the first lead 212 and the fourth lead 218 of the device substrate 10 .

Referring to FIG. 2 , in the present embodiment, the first lead 212 includes a first extension portion 2122 and a first branch portion 2124 . The first extension portion 2122 overlaps a corresponding first bonding pad 112 , and extends from a first column 110 A to a second column. The first branch portion 2124 is connected to an end 2122 a of the first extension portion 2122 close to the second column, and forms a right angle with the first extension portion 2122 . This may disperse stress and effectively prevent deformation of a first substrate in a press-fitting process.

The fourth lead 218 includes a fourth extension portion 2182 and a fourth branch portion 2184 . The fourth extension portion 2182 overlaps a corresponding fourth bonding pad 118 , and extends from the second column to the first column. The fourth branch portion 2184 is connected to an end 2182 a of the fourth extension portion 2182 close to the first column, and forms a right angle with the fourth extension portion 2182 . This may effectively prevent deformation of the first substrate in the press-fitting process.

In the present embodiment, the first lead 212 is bent to a first direction D 1 . In the present embodiment, the first extension portion 2122 extends along a first extension direction E 1 , and the first branch portion 2124 extends along the first direction D 1 . The fourth lead 218 is bent to a second direction D 2 . In the present embodiment, the fourth extension portion 2182 extends along a second extension direction E 2 , and the fourth branch portion 2184 extends along the second direction D 2 . The first direction D 1 is different from the second direction D 2 . In the present embodiment, the first direction D 1 is opposite to the second direction D 2 .

In the present embodiment, the first bonding pad 112 is staggered with the second bonding pad 114 . In other words, the first bonding pad 112 is not aligned with the second bonding pad 114 in the extension direction E 1 (or the extension direction E 2 ). A third bonding pad 116 is staggered with a fourth bonding pad 118 . In other words, the third bonding pad 116 is not aligned with the fourth bonding pad 118 in the extension direction E 1 (or the extension direction E 2 ).

In the present embodiment, a gap GP is present between the first column and the second column. In the present embodiment, a length L 1 of the first lead 212 overlapping the gap GP is different from a length L 3 of the third lead 216 overlapping the gap GP, and a length L 2 of the second lead 214 overlapping the gap GP is different from a length L 4 of the fourth lead 218 overlapping the gap GP.

In the present embodiment, the gap GP includes a first region R 1 , a second region R 2 , and a third region R 3 that have a same area and are connected in sequence. The first region R 1 is located between the first column 110 A and the second region R 2 . The third region R 3 is located between the second column 110 B and the second region R 2 . An area of a connection end L overlapping the first region R 1 is B′, an area of the connection end L overlapping the second region R 2 is A, and an area of the connection end L overlapping the third region R 3 is B. The area B and the area B′ may be the same or different. In the present embodiment, 1<A/B<2.04, which may better disperse the stress in the press-fitting process, and improve utilization of cabling space. In some embodiments, 1<A/B′<2.04.

In the present embodiment, areas of all the first region R 1 , the second region R 2 , and the third region R 3 are AR, and 0.2≤(A+B+B′3AR<1/2.

Based on the above, the first lead 212 of the device substrate 20 includes the first extension portion 2122 and the first branch portion 2124 , and an angle is present between the first branch portion 2124 and the first extension portion 2122 . Therefore, a problem of deformation in a region between the first bonding pad 112 and the second bonding pad 114 in a press-fitting process of the first bonding pad 112 on the first substrate and the first lead 212 on a second substrate of the device substrate 20 may be resolved, and a desired effect may be achieved in this design range.

FIG. 3 is a schematic top view of a device substrate according to an embodiment of the disclosure. It should be noted herein that, the embodiment of FIG. 3 follows reference numerals of components and some content in the embodiment of FIG. 2 , where the same or similar reference numerals are used to represent the same or similar components and the descriptions of the same technical content are omitted. For the explanation of the omitted part, reference may be made to the preceding embodiment and the descriptions thereof are omitted herein.

A main difference between a device substrate 30 and the device substrate 20 is as follows: Bonding pads P of the device substrate 30 further include a plurality of fifth bonding pads 142 , a plurality of sixth bonding pads 144 , a plurality of seventh bonding pads 146 , and a plurality of eighth bonding pads 148 , and connection ends L of the device substrate 30 further include a plurality of fifth leads 252 , a plurality of sixth leads 254 , a plurality of seventh leads 256 , and a plurality of eighth leads 258 .

In the present embodiment, first bonding pads 112 , third bonding pads 116 , the fifth bonding pads 142 , and the seventh bonding pads 146 are arranged in a first column 110 A, and second bonding pads 114 , fourth bonding pads 118 , the sixth bonding pads 144 , and the eighth bonding pads 148 are arranged in a second column 110 B. In the present embodiment, an end of the first bonding pad 112 facing the second column 110 B is not aligned with ends of the third bonding pad 116 , the fifth bonding pad 142 , and the seventh bonding pad 146 facing the second column 110 B, and an end of the second bonding pad 114 facing the first column 110 A is not aligned with ends of the fourth bonding pad 118 and the eighth bonding pad 148 facing the first column 110 A. In the present embodiment, the end of the second bonding pad 114 facing the first column 110 A is aligned with an end of the sixth bonding pad 144 facing the first column 110 A.

In the present embodiment, a length X 1 of each first bonding pad 112 is different from a length X 3 of each third bonding pad 116 , a length X 5 of each fifth bonding pad 142 , and a length X 7 of each seventh bonding pad 146 . In the present embodiment, a length X 2 of each second bonding pad 114 is different from a length X 4 of each fourth bonding pad 118 and a length X 8 of each eighth bonding pad 148 . In the present embodiment, the length X 2 of each second bonding pad 114 is equal to a length X 6 of each sixth bonding pad 144 . In the present embodiment, the length of each bonding pad P may be adjusted according to an actual requirement.

A first lead 212 includes a first extension portion 2122 and a first branch portion 2124 connected to the first extension portion 2122 . The first extension portion 2122 overlaps a corresponding first bonding pad 112 , and extends from the first column 110 A to the second column 110 B.

A second lead 214 includes a second extension portion 2142 . The second extension portion 2142 overlaps a corresponding second bonding pad 114 , and extends from the second column 110 B to the first column 110 A.

A third lead 216 includes a third extension portion 2162 . The third extension portion 2162 overlaps a corresponding third bonding pad 116 , and extends from the first column 110 A to the second column 110 B.

A fourth lead 218 includes a fourth extension portion 2182 and a fourth branch portion 2184 connected to the fourth extension portion 2182 . The fourth extension portion 2182 overlaps a corresponding fourth bonding pad 118 , and extends from the second column 110 B to the first column 110 A.

The fifth lead 252 includes a fifth extension portion 2522 and a fifth branch portion 2524 connected to the fifth extension portion 2522 . The fifth extension portion 2522 overlaps a corresponding fifth bonding pad 142 , and extends from the first column 110 A to the second column 110 B.

The sixth lead 254 includes a sixth extension portion 2542 . The sixth extension portion 2542 overlaps a corresponding sixth bonding pad 144 , and extends from the second column 110 B to the first column 110 A.

The seventh lead 256 includes a seventh extension portion 2562 . The seventh extension portion 2562 overlaps a corresponding seventh bonding pad 146 , and extends from the first column 110 A to the second column 110 B.

The eighth lead 258 includes an eighth extension portion 2582 and an eighth branch portion 2584 connected to the eighth extension portion 2582 . The eighth extension portion 2582 overlaps a corresponding eighth bonding pad 148 , and extends from the second column 110 B to the first column 110 A.

In the present embodiment, a gap GP is present between the first column 110 A and second column 110 B, and a width of the gap GP is equal to a shortest horizontal distance between the first column 110 A and the second column 110 B. The gap GP is located between a connection line of the end of the first bonding pad 112 facing the second column 110 B and a connection line of the end of the second bonding pad 114 facing the first column 110 A.

A length L 1 of the first lead 212 overlapping the gap GP, a length L 2 of the second lead 214 overlapping the gap GP, a length L 3 of the third lead 216 overlapping the gap GP, a length L 4 of the fourth lead 218 overlapping the gap GP, a length L 5 of the fifth lead 242 overlapping the gap GP, a length L 6 of the sixth lead 244 overlapping the gap GP, a length L 7 of the seventh lead 246 overlapping the gap GP, and a length L 8 of the eight lead 248 overlapping the gap GP are different from each other.

In the present embodiment, the gap GP includes a first region R 1 , a second region R 2 , and a third region R 3 that have a same area and are connected in sequence. The first region R 1 is located between the first column 110 A and the second region R 2 . The third region R 3 is located between the second column 110 B and the second region R 2 . Areas of the connection end L overlapping the first region R 1 , the second region R 2 , and the third region R 3 are B′, A, and B respectively. The area B and the area B′ may be the same or different. In the present embodiment, 1<A/B<3.6, which may better disperse stress in a press-fitting process, and improve utilization of cabling space. In some embodiments, 1<A/B′<3.6.

In some embodiments, areas of all the first region R 1 , the second region R 2 , and the third region R 3 are AR, and 0.15≤(A+B+B′)3AR<1/3.

Based on the above, the first lead 212 of the device substrate 30 includes the first extension portion 2122 and the first branch portion 2124 , and an angle is present between the first branch portion 2124 and the first extension portion 2122 . Therefore, a problem of deformation in a region between the first bonding pads 112 and the second bonding pads 114 in a press-fitting process of the first bonding pads 112 and the first leads 212 of the device substrate 30 may be resolved, and a desired effect may be achieved in this design range.