Circuit substrate structure and method for manufacturing thereof

This application claims priority to Taiwanese Application Serial Number 102100947 filed Jan. 10, 2013, which is herein incorporated by reference.

The present disclosure relates to a circuit substrate structure, and more particularly, to a circuit substrate structure having a flattening material layer.

FIG. 1 is a sectional view of a traditional circuit substrate structure 100 , which includes a substrate 110 , a pixel array layer 120 , a display unit 130 an integrated circuit chip 140 , a flexible printed circuit board 150 , a passivation layer 160 and a sealant 170 .

In FIG. 1 , the pixel array layer 120 is positioned on the substrate 110 , and has a display area (not shown) and a non-display area (not shown). The display area 130 is positioned on the display area of the pixel array layer 120 . The integrated circuit chip 140 and the flexible printed circuit board 150 are positioned on the non-display area of the pixel array layer 120 , and electrically connected to each other through the pixel array layer 120 . The passivation layer 160 covers the display unit 130 . Then the sealant 170 is infiltrated by capillary action into the space between the passivation layer 160 and the pixel array layer 120 , and cured by heating.

However, in a traditional display device, the sealant 170 is originally in liquid form without a fixed shape, so that the surface of the non-display area of the display area is not even. Besides, since the structure of the traditional display device has a difference in height forming several blind angles, the sealant 170 fails to uniformly infiltrate thereinto and thus generate several bubbles 180 . The bubbles 180 , after the heat-curing step of the sealant 170 , are expanded to lift off the passivation layer 160 and the display unit 130 , so as to deteriorate the reliability of the display device. Therefore, there is a need for an improved circuit substrate structure and a method of manufacturing the same, so as to solve the problems met in the art.

The present disclosure provides a circuit substrate structure having a flattening material layer and a method for manufacturing thereof, so as to solve the problems of the prior art and achieve the purpose of flattening the display device.

One embodiment of the present disclosure is to provide a circuit substrate structure. The circuit substrate structure comprises a substrate, a pixel array layer, a display unit, a peripheral circuit layer, at least one integrated circuit chip, a flexible printed circuit board, at least on flattening material layer and a passivation layer. The substrate has a display area and a non-display area. The pixel array layer is positioned on the display area of the substrate. The display unit is positioned on the pixel array layer. The peripheral circuit layer is positioned on the non-display area of the substrate, and electrically connected to the pixel array layer. The integrated circuit chip is positioned on the peripheral circuit layer, and electrically connected to the pixel array layer. The flexible printed circuit board is positioned on the peripheral circuit layer, and electrically connected to the integrated circuit chip, the pixel array layer or the combinations thereof. The flattening material layer is positioned on the peripheral circuit layer, and covers a portion of the flexible printed circuit board. Wherein the flattening material layer has at least one opening which corresponds to and surrounds the integrated circuit chip. The passivation layer is positioned on and covers the display unit and the flattening material layer.

Another embodiment of the present disclosure is to provide a method for manufacturing the circuit substrate structure. The method for manufacturing the circuit substrate structure comprises providing a substrate having a display area and a non-display area, forming a pixel array layer on the display area of the substrate, forming a display unit on the pixel array layer, forming a peripheral circuit layer, on the non-display area of the substrate, forming at least one integrated circuit chip, on the peripheral circuit layer, forming a flexible printed circuit board on the peripheral circuit board, forming at least one flattening material layer on the peripheral circuit layer, and forming a passivation layer on the display unit and the flattening material layer. In which, the peripheral circuit layer is electrically connected to the pixel array layer. The integrated circuit chip is electrically connected to the pixel array layer. The flexible printed circuit board is electrically connected to the integrated circuit chip, the pixel array layer or the combinations thereof. The flattening material layer covers a portion of the flexible printed circuit board, and has at least one opening corresponding to and surrounding the integrated circuit chip.

For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a sectional view of a traditional circuit substrate structure 100 ;

FIG. 2A is a three dimensional view of a circuit substrate structure 200 a according to one embodiment of the present disclosure;

FIG. 2B is an exploded view of the circuit substrate structure 200 a of FIG. 2A ;

FIG. 2C is a sectional view of the circuit substrate structure 200 a taken along the line A-A′ of FIG. 2A ;

FIG. 2D is a sectional view of a circuit substrate structure 200 b according to one embodiment of the present disclosure;

FIG. 3A to 3G are sectional views of making a circuit substrate structure 300 a according to one embodiment of the present disclosure; and

FIG. 3H to 3I are sectional views of making a circuit substrate structure 300 b according to one embodiment of the present disclosure.

The embodiments of the circuit substrate structure and the method for manufacturing the same of the present disclosure are discussed in detail below, but not limited the scope of the present disclosure. The same symbols or numbers are used to the same or similar portion in the drawings or the description. And the applications of the present disclosure are not limited by the following embodiments and examples which the person in the art can apply in the related field.

FIG. 2A is a three dimensional view of a circuit substrate structure 200 a according to an embodiment of the present disclosure, and FIG. 2B is an exploded view of the circuit substrate structure 200 a of FIG. 2A . The circuit substrate structure 200 a comprises a substrate 210 , a pixel array layer 220 , a display unit 230 , a peripheral circuit layer 240 , at least one integrated circuit chip 250 , a flexible printed circuit board 260 , at least one flattening material layer 270 a and a passivation layer 280 .

In FIGS. 2A and 2B , the substrate 210 has a display area 211 and a non-display area 212 . And the pixel array layer 220 and the display unit 230 is positioned sequentially on the display area 211 of the substrate 210 . According to one example of the present disclosure, the material of the substrate 210 comprises glass, hard plastics or flexible plastics. According to one example of the present disclosure, the pixel array layer 220 comprises a thin-film transistor layer. According to one example of the present disclosure, the display unit 230 comprises a front panel, a liquid crystal display medium layer, or a light-emitting diode display medium layer. The front panel includes an E-paper medium layer, such as electrophoretic display medium layer.

The peripheral circuit layer 240 is positioned on the non-display area 212 of the substrate 210 , and electrically connected to the pixel array layer 220 . The integrated circuit chip 250 , the flexible printed circuit board 260 and the flattening material layer 270 a are positioned on the peripheral circuit layer 240 . According to one example of the present disclosure, the peripheral circuit layer 240 comprises a thin-film transistor layer or a conductive circuit layer. According to one example of the present disclosure, the integrated circuit chip 250 comprises a driving circuit chip.

The flattening material layer 270 a covers a portion of the flexible printed circuit board 260 , and has at least one opening 271 a . Each opening 271 a corresponds to and surrounds the integrated circuit chip 250 . Then, the passivation layer 280 is positioned on and covers the display unit 230 and the flattening material layer 270 a . According to one example of the present disclosure, the material of the passivation layer 280 comprises flexible plastics.

FIG. 2C is a sectional view of the circuit substrate structure 200 a taken along the line A-A′ of FIG. 2A . In FIG. 2C , the flattening material layer 270 a is positioned on the peripheral circuit layer 250 , and the integrated circuit chip 250 is in the opening 271 a . Besides, the flattening material layer 270 a is contacted tightly with the neighboring display unit 230 , and the passivation layer 280 can directly cover the flattening material layer 270 a and the display unit 230 without filling a sealant.

FIG. 2D is a sectional view of a circuit substrate structure 200 b according to one embodiment of the present disclosure. In FIG. 2D , a flattening material layer 270 b is positioned on the peripheral circuit layer 250 , and the integrated circuit chip 250 is in a opening 271 b . The flattening material layer 270 b is not contacted with the display unit 230 , and a sealant 290 is positioned between the flattening material layer 270 b and the display unit 230 . According to one example of the present disclosure, the sealant 290 is positioned between the flattening material layer and the display unit, and in the opening 291 b of the flattening material layer 270 b . According to one example of the present disclosure, the sealant 290 is heat curing adhesive, optical light-sensitive adhesive or after-light-sensitive heat curing adhesive. According to one example of the present disclosure, the flattening material layer 270 b covers more than 50% of the non-display area 212 of the substrate 210 .

According to one example of the present disclosure, the coefficient of linear thermal expansion of the flattening material layer 270 a or 270 b is less than 70×10 −6 /K. According to one example of the present disclosure, the material of the flattening material layer 270 a or 270 b comprises glass, polyethylene terephthalate (PET), polyethylene naphthalene dicarboxylate (PEN), polymethyl methacrylate (PMMA), polycarbonate (PC), polystyrene (PS), or the combinations thereof. According to one example of the present disclosure, the thickness of the flattening material layer 270 a or 270 b is the same as the thickness of the display unit 230 . According to one example of the present disclosure, the thickness of the flattening material layer 270 a or 270 b is larger than or equal to the integrated circuit chip 250 .

FIG. 3A to 3G are sectional views of making the circuit substrate structure 300 a according to one embodiment of the present disclosure. In FIG. 3A , a substrate 310 is provided and has a display area 311 and a non-display area 312 . Then, a pixel array layer 320 is formed on the display area 311 of the substrate 310 , shown as FIG. 3B . In FIG. 3C , a display unit 330 is formed on the pixel array layer 320 .

In FIG. 3D , a peripheral circuit layer 340 is formed on the non-display area 312 of the substrate 310 , in which the peripheral circuit layer 340 is electrically connected to the pixel array layer 320 . Then at east one integrated circuit chip 350 and a flexible printed circuit board 360 is formed on the peripheral circuit layer 340 , shown as FIG. 3E .

In FIG. 3F , a flattening material layer 370 a is formed on the peripheral circuit layer 340 and contacted tightly with the neighboring display unit 330 , and covers a portion of the flexible printed circuit board 360 . The flattening material layer 370 a has at least one opening 371 a , and the opening 371 a corresponds to and surrounds the integrated circuit chip 350 . According to one example of the present disclosure, the flattening material layer 370 a can be used to protect the integrated circuit chip 350 .

In FIG. 3G , a passivation layer 380 is formed on and covers the display unit 330 and the flattening material layer 370 a , so as to form the circuit substrate structure 300 a . Because the flattening material layer 370 a is tightly contacted with the display unit 330 without a gap, there is no need to fill with a sealant. The passivation layer 380 can cover directly the display unit 330 and the flattening material layer 370 a , and the circuit substrate structure 300 a having flattening surface is provided. Thus, the step of optical or heat curing of the sealant is negligible, so as to reduce the manufacturing cost and prevent from the destruction of the heat treatment process on the display unit.

Noteworthy, because the flattening material layer 370 a is tightly contacted with the display unit 330 without a gap, the circuit substrate structure 300 a cannot occur the bubble issue as the prior art. According to one example of the present disclosure, the circuit substrate structure 300 a can be applied to a display device.

FIG. 3H to 3I are sectional views of making a circuit substrate structure 300 b according to one embodiment of the present disclosure. FIG. 3H is followed by the structure shown in FIG. 3E . In FIG. 3H , a flattening material layer 370 b is formed on the peripheral circuit layer 340 , and covers a portion of the flexible printed circuit board 360 . The flattening material layer 370 b has at least one opening 371 b , and the opening 371 b corresponds to and surrounds the integrated circuit chip 350 . A sealant 390 is formed between the flattening material layer 370 b and the display unit 330 , and in the opening 371 b of the flattening material layer 370 b . According to one example of the present disclosure, the sealant 390 is formed only between the flattening material layer 370 b and the display unit 330 . According to one example of the present disclosure, the flattening material layer 370 b can be used to protect the integrated circuit chip 350 .

In FIG. 3I , a passivation layer 380 is formed on and covers the display unit 330 and the flattening material layer 370 b , so as to form the circuit substrate structure 300 b . And then the circuit substrate structure 300 b should be performed the optical or heat curing step of the sealant 390 , so as to provide a circuit substrate structure 300 b having flattening surface. According to one example of the present disclosure, the circuit substrate structure 300 b can be applied to a display device.

Unlike to the traditional process, the method for manufacturing the circuit substrate structure 300 b as one example of the present disclosure is firstly forming the sealant 390 between the flattening material layer 370 b and the display unit 330 , and then covering the passivation layer 380 . This helps to avoid blind angle generated due to a height difference in the circuit substrate structure, and bubbles formed in the sealant filling. Besides, the method provided in the present disclosure can efficiently solve the bubble issue generated in the art.

It is noteworthy that the usage amount and area of the sealant, according to the embodiments of the present disclosure, can be significantly reduced by adding the flattening material layer into the circuit substrate structure, so as to achieve the purpose of flattening the surface of the circuit substrate structure. On the other hand, the method provided in the present disclosure can also solve the bubble issue generated in the circuit substrate structure. According to the example of the present disclosure, the steps of filling sealant and optical or heat curing can be completely omitted in the process of manufacturing the circuit substrate structure, so as to reduce the product cost and prevent the display device from the destruction after the heat-treatment.

Although embodiments of the present disclosure and their advantages have been described in detail, they are not used to limit the present disclosure. It should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the present disclosure. Therefore, the protecting scope of the present disclosure should be defined as the following claims.