TW591988B - Printed circuit board with compensation of heat expansion effect - Google Patents

Abstract

A kind of printed circuit board (PCB) capable of preventing from accumulation of heat expansion effect is disclosed in the present invention, in which plural thermally pressed regions are provided on the bottom side of PCB. By opening a recessed trench on the surface of the PCB bottom side and forming the recessed trench in between these two thermally pressed regions, the expansion of PCB due to material expansion/cold-contraction effect in high-temperature process can be prevented. The invention is capable of solving the problem of production yield decrease caused by over-large stress on both sides of PCB such that the design for compensating thermal expansion becomes much easier.

Description

591988

V. Description of the invention (1) [Technical field to which the invention belongs] The present invention relates to a printed circuit board, and more particularly, to a printed circuit board capable of preventing accumulation of thermal expansion effects. [Previous Technology] Printed Circuit Board (PCB) is the main support for the installation and insertion of electronic components. The main function is to design the circuit of various electronic components through printed circuit boards. To achieve the purpose of relay transmission, so that the functions of various components can be brought into play, which is an indispensable basic constituent element of all electronic information products. The printed circuit board can be electrically connected to other substrates or interfaces after being connected to the flexible circuit board. For example, the printed circuit board can be connected to a glass substrate as a liquid crystal display panel through a flexible circuit board to obtain a liquid crystal display module (LCM). In the process of manufacturing a liquid crystal display module, a plurality of electrodes on a printed circuit board in the liquid crystal display module are bonded to a plurality of electrodes on a flexible circuit board by a thermocompression process. Please refer to Fig. 1A. Fig. 1a shows the schematic diagram of the liquid crystal display module before the thermocompression process. The liquid crystal display module includes a printed circuit board 10, a plurality of flexible circuit boards 12, and a glass substrate 13 connected to the flexible circuit board 12. The printed circuit board 10 has a plurality of electrodes (pads) 4 on the bottom side, which are respectively disposed in the thermocompression bonding area 11. Each flexible circuit board 12 is also provided with a plurality of electrodes 15 respectively, and the electrodes 15 correspond to the electrodes 14 in the thermocompression bonding area. Among them, the thermocompression bonding area i i on the bottom side of the printed circuit board 丨 0

TW1117F (AUO) .ptd Page 4 5. Description of the Invention (2) It is the area where the printed circuit board 10 and the flexible circuit board 2 are connected. Please refer to FIG. 1B, which is a cross-sectional view in the direction of the line 1B-1B ′ of the liquid? In the thermocompression bonding system :: The state module is first coated with an electrically conductive (Anisotropic Conductive Film, ACF) 18 ^ 1 between the circuit board 12 and the printed circuit board 10, and there are multiple conductive particles in U. In a thermocompression bonding system: Direction: The conductive adhesive 18 will make the electrodes of the flexible circuit board 12 ^ directional conductive 14 is limited to electrical conduction in 2 directions only. P brushing the electrodes of the circuit board 10 During the thermal compression bonding process, the composition materials of the flexible circuit board 12 are different, so the circuit board 10 is different from the circuit board 10. Before the thermocompression process, the pitch of the expansion coefficients of the flexible capacitors is also CU, and the corresponding electrode 15 on the 12: side is 仏. In order to make the flexible circuit board 12: == 5: the solid electrode " the spaced electrode 14 can be used in the high temperature state of the thermocompression bonding process: ": brush": 10 on the printed circuit board 1 0 in the X direction The width of 埶 β t-bit junction must be expanded compensation value. Refer to Section 1 (: Figure, its location, green), Effect Design-Thermal Indicator Module Along the section line 1B_1β, direction 2 1 "section of the liquid crystal display Illustration. The high temperature during the hot-pressing process; = the expansion of the distance between the electrodes 15 on both sides in the state of the south temperature of the heart is dl, and the distance between the two electrodes 14 of the flexible circuit board 12 is d2 ,, dl: The electrode 15 on the printed circuit board 10 and the printed circuit 'd2' are soft-bonded. The upper electrodes 1 and 4 will work. However, during the thermal compression process, the thermal expansion from 2 °° will make the original square two? Indicator module circuit board 1 2 a, 591988 5. Description of the invention (3) 1 2 b, 1 2 c, and 1 2 d will be deformed after being hung. Please refer to Figure 2 / Fig. Λ The influence of swelling of printed circuit board 10 Mo Niuxi :: LCD display after thermal expansion Softness i: 2: 2. The imaginary line 3 ° in the center of the second printed circuit board 10 is used as a reference, = the flexible circuit board towards the direction E1 ... and the bulging effect is caused by the printed electrical two: "two:" board = body thermal expansion circuit board U) outer edge Part of the flexible circuit board is printed in the soft part of the central part of the printed circuit board 10 ;: f is printed here, and the closer it is to the printed circuit board 10, the larger it is: the larger the deformation phenomenon, the more obvious it will be. The two ... The flexible circuit board 12 will later: 'ί ί, after the i process, the liquid crystal display module 20 ° will shrink after cooling. The flexible circuit board 12a, which was originally deformed during the thermocompression process, was affected. 12b, 12: = circuit board 1? The effect of cooling shrinkage is taken again. Taking the printing second way! 2: The central imaginary line 30 as the reference, the flexible circuit boards 12a and 12b are oriented = the flexible circuit boards 120 and 1 2d is pushed towards the direction S2 and turned into a ladder. During the entire hot-pressing process, the printed circuit board is prone to expand due to high height, and it will shrink after cooling. Xiao The connection of printed circuit boards is soft: Road board text Due to the expansion and contraction of the printed circuit, it is easy to cause softness. It is especially heavy near the outer edge of the printed circuit board. This is due to the thermal expansion of the outer edge of the printed circuit board, which is larger than the middle part of the printed circuit board. The stress accumulates as the size of the printed circuit board 10 increases. Large, then this is due to hot pressing

TW1117F (Youda) .Ptd Page 6 591988 5. Description of the Invention (4) The more severe the phenomenon that the printed circuit board 10 expands outwards and contracts inwardly, it also causes the circuit of the flexible circuit board 12 to break and damage, which Production yield is reduced. In addition, the hot-pressing process can use a long hot-pressing head that performs the hot-pressing process on the entire printed circuit board at one time, or a short hot-pressing head that performs the hot-pressing process on only one hot-pressing region 11 at a time. Since the thermal expansion effect of the printed circuit board is accumulated from the center to the outer edge, different thermal expansion compensation values must be designed for the long thermal head and the short thermal head. Furthermore, it is necessary to design different thermal expansion compensation values for different thermocompression bonding regions 11. The cumulative situation of thermal expansion of the printed circuit board i 〇 will also make the design of the thermal expansion compensation value difficult. SUMMARY OF THE INVENTION In view of this, an object of the present invention is to provide a printed circuit board that can prevent the accumulation of thermal expansion effects, and has a plurality of thermocompression bonding s y domains on its bottom side. By opening a groove on the surface of the bottom side of the printed circuit board, and making the groove between the two hot-pressed areas, the expansion of the material's expansion and contraction effect during high temperature processing can be prevented. . The invention solves this problem: the two ends of the road board are caused by too much stress, which leads to a good "low interrogation" of production and makes the design of the thermal expansion compensation value easier. The invention proposes a printed electrical J that can prevent the thermal expansion effect from accumulating. Printing: The bottom side of the circuit board has a plurality of thermocompression bonding areas. The surface on the side of the groove 1 is located between two adjacent thermocompression bonding regions. 1 During the compression bonding process, a plurality of softnesses are pressed by a thermal compression head. Circuit board and printed circuit; electric:

591988 V. Description of the invention (5) 'Connection. Among them, the printed circuit board can use the electrodes on the heat-bonded area to individually align the electrodes corresponding to the individual flexible circuit boards, thereby connecting the printed circuit board to a plurality of flexible circuit boards. The groove may be square, semi-circular, or any shape, and the visibility of the groove is smaller than the interval between two adjacent compression areas. Furthermore, the number of grooves between two adjacent heat-bonded regions is not limited to one or two. In order to make the above-mentioned objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is given below in conjunction with the accompanying drawings for detailed description, such as [preferred embodiment] The present invention is specially designed to prevent The thermal expansion effect accumulates on the printed circuit board, and has a plurality of thermocompression bonding areas on its bottom side. The invention provides a groove on the bottom surface of the printed circuit board, and the groove is interposed between two thermocompression bonding regions. In this way, the material expansion and cold shrinkage effects of the printed circuit board during high temperature processing can be prevented. Expansion. The invention can solve the problem that the yield of the printed circuit board is reduced due to excessive stress at both ends of the printed circuit board, and the design of the thermal expansion compensation value is easier. First Embodiment Please refer to FIG. 3A, which shows a schematic diagram of a liquid crystal display module 300 according to a first embodiment of the present invention. In Fig. 3A, the bottom side of the printed circuit board 30 is connected to one side of a plurality of flexible circuit boards 32, and the other side of the flexible circuit board 32 is connected to a glass substrate 13. Printed circuit board bottom 30

TW1117F (友 达) .ptd Page 8 591988 5. Description of the invention (6) There are multiple thermocompression bonding areas 31 on the side, and the hot press plate 30 is used to connect F β to the flexible circuit board 32, which is on the printed circuit side. There are multiple electrodes, which are respectively at the bottom of the circuit board 30. α is straight to the thermocompression bonding area and a plurality of electrodes are arranged on the bottom surface of each flexible circuit board 32. When pressing the bonding process, first apply it to the flexible circuit board Tianjin仃…, the anisotropic conductive adhesive between the electrodes on the top (Wilun Qianqian 筮 q Α 面 二 丨 %% road board 葩 xi m seven groups of ancient, Tianxi 柞 田 & 2 in the 3A picture) will be due to heat The pressure of the indenter and the plate: the SM d'makes the flexible circuit board printed circuit board: the electrodes are bonded and electrically connected, and the parallel plate 30 can be connected to the flexible circuit board 32. Through this connection, the square plate 30 can multi-sent electrical Connected to the $ 10 side of the soft circuit board 32 = substrate 1 3. The present invention is on the bottom side of the printed circuit board 30 and is located between two adjacent thermocompression bonding areas 31, i is less open A groove 39. Please refer to the liquid crystal display module 300 shown in FIG. Schematic diagram of thermal expansion. During the thermal compression process, the concave design allows each single thermal compression region 3 on the printed circuit board 30 to be affected: the expansion can be considered independently, and each single thermal compression Area 3 丨; 埶 ^ = the amount will not affect the thermal expansion of the adjacent hot-pressed areas on both sides. The design can solve the traditional printed circuit board 丨 〇 the overall thermal expansion problems should be generated. ', Ji Xi Referring to FIG. 3C, Ai is a schematic diagram of the liquid crystal display 300 shown in FIG. 3A after cooling and shrinking after the heat pressing process. After the heat pressing process, the printed circuit board 3 is printed. It is cooled. The design of the recesses 39 enables the shrinkage of each single heat-bonded area 31 of the printed circuit board 30 to be considered independently, and

TW1117F (Youda) .ptd Page 9 591988 5. Description of the invention (7) 1 The shrinkage of each single heat-bonded area 3 丨 will not affect the shrinkage of the two heat-bonded areas. Similarly, the design of the groove 39 can be equal to the problem caused by the cumulative effect of the cooling and shrinkage of the adjacent printed circuit board 10. The groove of the printed circuit board of the present invention can prevent thermal expansion =. In addition to the function, according to this design, the problem of stress accumulation caused by the thermal expansion of the printed circuit board can be reduced. The invention can further reduce the phenomenon that the flexible circuit board 32 is broken by the printed circuit board 30 and the circuit breakage of the flexible circuit board 32 is broken, and increase the production yield. In addition, when performing thermal compression bonding, compared with the case where the common printed circuit board 10 cannot use the same thermal expansion compensation value when using a long thermal head or a short two head, the thermal expansion according to the invention ^ f The compensation value can be applied to the process using long thermal head or short thermal head. & In Fig. 3A, the shape of the groove 39 is square, and the width of the groove 3g is smaller than the interval between two adjacent compression areas as an example. The shape of the groove 39 can also be a semi-circular shape, a diagonal shape, or an arbitrary shape. Second Embodiment Please refer to FIG. 4, which is a schematic diagram of a liquid crystal display module according to a second embodiment of the present invention. In Fig. 4, the bottom side of the printed circuit board 40 has a plurality of thermocompression bonding areas 41a and 41b. The difference from the first embodiment is that in this embodiment, more than two grooves 49 ° can be opened between two adjacent hot-pressing areas 4 1 a and 4 1 b. Third embodiment

591988 V. Description of the invention (8) Please refer to f. "A picture" is a liquid crystal display mode according to a third embodiment of the present invention, and it does not bear the picture. In FIG. 5, the bottom side of the printed circuit board 50 has a plurality of four grooves 59 and a plurality of thermocompression bonding areas 5a and 5lb. Each of the grooves 59 is located between the adjacent two heat-bonded areas 5 la and 5 lb. In this embodiment, the width of each groove 59 is only required to be smaller than the interval between two adjacent pressing areas, but it is not limited to a specific width. When the distance between two adjacent pressing areas is increased, the width of the groove 59 can be increased accordingly. However, those skilled in the art will understand that the technology of the present invention is not limited to this. The width of each groove can also be different on the same printed circuit board. In addition, any groove design known to those skilled in the art can be applied to the interval between two adjacent compression regions of the present invention, as long as it can achieve the effect of blocking thermal expansion or internal accumulation effect. The boards disclosed in the embodiments of the present invention and the above-mentioned implementation modes have the following advantages: 1) By adding a groove method, the cumulative effect of thermal expansion and contraction of the material of the printed circuit board during a high temperature process can be prevented, which can improve the Process stability and production yield. 2 · The thermal expansion of each single pressing area of the printed circuit board will not affect the adjacent heat pressing areas on both sides. Therefore, the thermal expansion of each thermal compression region can be as same as possible and independent of each other. It is not necessary to consider different thermal expansion compensation issues depending on the position of the straight centerline from the printed circuit board. And simplification. 3. The design of the same thermal expansion compensation value can be applied to the process using thermal head or short thermal head at the same time. This thermal expansion compensation value is longer than the transmission length

TW1117F (Youda) .ptd Page 11 591988 V. Description of the invention (9) Design, and in the heavy industry machine, the design of the thermal expansion compensation value can reduce the softness of the electrodes on both ends of the printed circuit board due to thermal compensation Poor alignment of the electrodes on the circuit board. 4. After the printed circuit board material is effectively controlled due to temperature variability, the printed circuit board can be researched and developed toward the goal of a smaller electrode pitch (P i t ch). In summary, although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make various changes without departing from the spirit and scope of the present invention. And retouching, so the scope of protection of the present invention shall be determined by the scope of the appended patent application.

TW1117F (Youda) .ptd Page 12 591988 Brief description of the drawings [Simplified description of the drawings] Figure 1A shows the schematic diagram of the LCD module before the hot-pressing process. FIG. 1B is a cross-sectional view of the liquid crystal display module in FIG. 1A along the direction of section line 1 B-1B ′. FIG. 1C is a cross-sectional view of the liquid crystal display module in FIG. 1A under the high-temperature state of the hot-pressing process along the direction of the section line 1 B-1 B ′. Figure 2A is a schematic diagram of a liquid crystal display module after thermal expansion. FIG. 2B is a schematic diagram showing the shrinkage of the material of the liquid crystal display module after the hot-pressing process. FIG. 3A is a schematic diagram of a liquid crystal display module according to a first embodiment of the present invention. FIG. 3B is a schematic diagram of the liquid crystal display module in FIG. 3A when it is thermally expanded during a hot-pressing process. FIG. 3C is a schematic diagram of the liquid crystal display module of FIG. 3A when it is cooled and contracted after the hot-pressing process. FIG. 4 is a schematic diagram of a liquid crystal display module according to a second embodiment of the present invention. FIG. 5 is a schematic diagram of a liquid crystal display module according to a third embodiment of the present invention. [Illustration of figure number] 1 0 0, 2 0 0, 3 0 0, 4 0 0, 5 0 0: LCD module

TW1117F (AUO) .ptd Page 13 591988 Brief description of the drawings 10, 30, 40, 50: Printed Circuit Board (PCB) 11, 31, 41a, 41b, 51a, 51b: Thermocompression bonding areas 12, 12a, 1 2b , 12c, 12d, 32: Flexible circuit board 13: Glass substrate 14, 15Electrode 18: Anisotropic conductive adhesive 3 9, 4 9, 5 9

El, E2, SI, S2: Force direction X, Z: Directions dl, d2, dl ', d2' ·· Pitch

TWllHF (友 达) .ptd Page 14

Claims (1)

591988 A printed circuit board has a bottom side connected to one side of a plurality of flexible circuits. The printed circuit board includes a plurality of thermocompression bonding areas, which are located on the bottom side of the printed circuit board and the bottom side of the flexible circuit board. A connection; and a groove, which is arranged on the bottom side of the printed circuit board and is located at a phase of 1 μm by thermocompression bonding. • The printed circuit board as described in item 1 of the scope of patent application, the bottom side of the printed circuit board has a plurality of electrodes, and each of the flexible circuit boards also has a plurality of electrodes corresponding to the printed circuit board. The electrodes of the circuit board are connected to the electrodes of the flexible circuit boards by a thermocompression bonding process. 3. The printed circuit board according to item 1 of the scope of patent application, wherein the width of the groove is smaller than the interval between two adjacent compression areas. 4. The printed circuit board according to item 1 of the scope of patent application, wherein the shape of the groove is a square, a semicircle or an angle. 5 · A printed circuit board capable of preventing the accumulation of thermal expansion effects, a bottom side of which is connected to one side of a plurality of flexible circuit boards, the printed circuit board includes: a plurality of thermocompression bonding areas located on the bottom side of the printed circuit board For connecting to the bottom side of the flexible circuit boards; and a plurality of grooves, which are arranged on the bottom side of the printed circuit board and located between two adjacent thermocompression bonding areas. 6 · The printed circuit board described in item 5 of the scope of patent application, the bottom side of the printed circuit board has a plurality of electrodes, and each of these flexible circuit boards also has a plurality of electrodes, and the electrodes of the printed circuit board are based on Hot pressing process and TW1117F (AUO) .ptd Page 15 591988 6. Scope of patent application The electrode connection of these flexible circuit boards. 7. The printed circuit board according to item 5 of the scope of patent application, wherein the width of the grooves is smaller than the interval between two adjacent compression areas. 8. The printed circuit board according to item 5 of the scope of patent application, wherein the shapes of the grooves are square, semi-circular, or angular. 9. The printed circuit board according to item 5 of the scope of patent application, wherein two grooves on the same printed circuit board have different widths. 10. —A liquid crystal display module using a printed circuit board that can prevent the accumulation of thermal expansion effects, the liquid crystal display module includes: a plurality of flexible circuit boards; a substrate, one side of which is connected to one side of the flexible circuit boards And a printed circuit board with its side connected, which is multiplexed with these to 11. 11. Wherein the printed circuit board has a manufacturing process and the 12. Such as the printed partition. The printed circuit board includes a plurality of thermocompression bonding areas, and the other side of the flexible circuit board is provided with a groove, which is arranged on the bottom side of the circuit board in the phase 10 of the patent application. The printed circuit board has a plurality of electrodes. The electrode is connected to the circuit board with a small groove width of the patent application No. 10, and the bottom side is connected to the flexible circuit boards. The printed circuit board is connected to the printed circuit board. The electrodes are connected to the mother circuit board. The liquid crystal is displayed between the bottom sides of two adjacent nips. Device, these soft-pressed thermocompression device modules, TW1117F (AUO) .ptd Page 16 591988 6. Application for patent scope 13. The LCD module as described in item 10 of the patent scope The groove shape of the printed circuit board is square, semi-circular or angular. 14. The liquid crystal display module according to item 10 of the scope of patent application, wherein the printed circuit board has a plurality of grooves, and two of the grooves have different widths. TW1117F (AUO) .ptd Page 17