Display module, preparation method thereof and display device

Abstract

The invention provides a display module and a preparation method thereof and a display device, the display module comprises at least two binding areas arranged on a display panel, and each binding area comprises a plurality of conductive parts arranged at intervals; the circuit board comprises at least two binding parts which are arranged at intervals, each binding part comprises a plurality of pins which are arranged at intervals, the plurality of pins of each binding part are in one-to-one correspondence with and are connected with the plurality of conductive parts of one binding area, and the first preshrinking ratio is controlled to be greater than the second preshrinking ratio, the preshrinking amount in the second preshrinking direction can be smaller than the preshrinking amount in the first preshrinking direction, so that the smaller preshrinking amount in the second preshrinking direction can counteract the smaller swelling amount in the second thermal expansion direction, and the larger preshrinking amount in the first preshrinking direction can counteract the larger swelling amount in the first thermal expansion direction; therefore, after hot-pressing binding, each pin on the circuit board can be accurately aligned with the corresponding conductive part and is in binding connection with the conductive part, and the binding alignment precision of the circuit board is improved.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a display module and a preparation method thereof, and a display device. Background Art

[0002] There are two main structures of existing large-size flexible printed circuits (FPC): one is that the binding part is continuous without disconnection, and the other is that the two binding parts are disconnected between adjacent binding parts, and the two binding parts form a "U" shape. For the "U"-shaped circuit board, due to the particularity of its structure, after binding and aligning with the display panel, the alignment offset between the bound flexible circuit board and the display panel is large, and the alignment accuracy is poor. Summary of the invention

[0003] In view of this, the purpose of the present application is to provide a display module and a manufacturing method thereof and a display device.

[0004] Based on the above objectives, the first aspect of the present application provides a display module, including:

[0005] A display panel, wherein at least two binding areas are provided on the display panel, and each of the binding areas includes a plurality of conductive parts arranged at intervals;

[0006] A circuit board, comprising at least two binding parts arranged at intervals, each of the binding parts comprising a plurality of pins arranged at intervals, and the plurality of pins of each binding part corresponding to and connected with the plurality of conductive parts of a binding area one by one;

[0007] The distance between the first central axis of the first pin of each binding portion and the second central axis of the binding portion is the first distance, the distance between the third central axis of the first conductive portion of the binding area corresponding to the binding portion and the fourth central axis of the binding area is the second distance, the first pin is a pin far away from the first central axis among the plurality of pins, the first conductive portion is a conductive portion corresponding to the first pin, and the ratio of the difference between the second distance and the first distance to the second distance is the first pre-shrinkage ratio;

[0008] The distance between the second central axes of two adjacent binding parts is a third distance, the distance between the fourth central axes of two adjacent binding areas is a fourth distance, and the ratio of the difference between the fourth distance and the third distance to the fourth distance is a second pre-shrinkage ratio;

[0009] The first pre-shrinkage ratio is greater than the second pre-shrinkage ratio.

[0010] A second aspect of the present application provides a method for preparing a display module, comprising:

[0011] A display panel is provided, wherein at least two binding areas are provided on the display panel, each of the binding areas comprises a plurality of conductive parts arranged at intervals, wherein a distance between a third central axis of a first conductive part of the binding area and a fourth central axis of the binding area is a second distance, and a distance between the fourth central axes of two adjacent binding areas is a fourth distance;

[0012] Determining a first pre-shrinkage ratio and a second pre-shrinkage ratio of a circuit board, wherein the first pre-shrinkage ratio is greater than the second pre-shrinkage ratio, the circuit board comprising at least two binding parts arranged at intervals, each of the binding parts comprising a plurality of pins arranged at intervals;

[0013] Based on the first pre-shrinkage ratio, the second pre-shrinkage ratio, the second distance and the fourth distance, determining a pre-shrinkage size of the circuit board to obtain a pre-shrinkage circuit board;

[0014] Each binding part of the pre-shrunk circuit board is aligned with a binding area of ​​the display panel and is bound and connected by a hot pressing process, so that multiple pins of each binding part correspond to multiple conductive parts of a binding area one by one and are bound and connected.

[0015] A third aspect of the present application provides a display device, comprising the display module described in any one of the first aspect or the display module described in any one of the second aspect.

[0016] From the above, it can be seen that the display module, preparation method thereof and display device provided by the present application control the first preshrinkage ratio to be greater than the second preshrinkage ratio, so that during the preshrinkage design, the preshrinkage amount in the second preshrinkage direction is smaller than the preshrinkage amount in the first preshrinkage direction. In this way, the smaller preshrinkage amount in the second preshrinkage direction can just offset the smaller expansion amount in the second thermal expansion direction, and the larger preshrinkage amount in the first preshrinkage direction can just offset the larger expansion amount in the first thermal expansion direction, thereby enabling each pin on the circuit board to be accurately aligned and bound to the corresponding conductive part after hot pressing and binding, thereby improving the binding and alignment accuracy of the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present application or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1a It is a structural schematic diagram of a circuit board in which the binding part is overall continuous and unbroken in the related art;

[0019] Figure 1bIt is a structural schematic diagram of a circuit board with disconnected adjacent binding parts in the related art;

[0020] Figure 1c It is a structural schematic diagram of a flexible circuit board and a substrate after being bound and connected in the related art;

[0021] Figure 2a to Figure 2c A structural diagram of the first pre-shrinking method for designing a related "U"-shaped large FPC;

[0022] Figure 3a to Figure 3c A structural diagram of the second pre-shrinking method for designing a related "U"-shaped large FPC;

[0023] Figure 4 This is a schematic diagram of a first structure of a display module according to an embodiment of the present application;

[0024] Figure 5 A second structural schematic diagram of a display module according to an embodiment of the present application;

[0025] Figure 6 Attached to the instruction manual Figure 5 A partial enlarged schematic diagram of Y in the middle;

[0026] Figure 7 This is a schematic diagram of the first heating principle of the circuit board of the embodiment of the present application;

[0027] Figure 8 A third structural schematic diagram of the display module of the embodiment of the present application;

[0028] Fig. 9 A fourth structural schematic diagram of a display module according to an embodiment of the present application;

[0029] Fig.10 Attached to the instruction manual Fig. 9 A partial enlarged schematic diagram of

[0030] Fig.11 This is a schematic diagram of the first structure of the circuit board of an embodiment of the present application;

[0031] Fig.12 A fifth structural schematic diagram of the display module according to an embodiment of the present application;

[0032] Fig.13 A schematic diagram of the structure of a display panel according to an embodiment of the present application;

[0033] Fig.14 A sixth structural schematic diagram of a display module according to an embodiment of the present application;

[0034] Fig.15 A seventh structural schematic diagram of the display module of the embodiment of the present application;

[0035] Fig.16Attached to the instruction manual Fig.15 A partial enlarged schematic diagram of

[0036] Fig.17 A schematic diagram of the structure of the display module of an embodiment of the present application when a hot pressing process is performed;

[0037] Fig.18 This is a schematic diagram of an eighth structure of the display module according to an embodiment of the present application;

[0038] Fig.19 This is a schematic diagram of a second heating principle of a circuit board according to an embodiment of the present application;

[0039] Fig. 20 This is a schematic diagram of the principles of the circuit board before and after binding according to an embodiment of the present application;

[0040] Fig.21 A second structural schematic diagram of a circuit board according to an embodiment of the present application;

[0041] Fig. 22 A third structural schematic diagram of the circuit board of an embodiment of the present application;

[0042] Fig.23 A ninth structural schematic diagram of a display module according to an embodiment of the present application;

[0043] Fig.24 This is a schematic structural diagram of the first pin and the first conductive portion of the display module after alignment in an embodiment of the present application;

[0044] Fig.25 This is a fourth structural schematic diagram of the circuit board of an embodiment of the present application.

[0045] In the figure: 01, flexible circuit board; 011, gold finger; 02, substrate; 03, conductive contact; 04, IC; 1, display panel; 11, binding area; 111, conductive part; 1111, first conductive part; 112, alignment conductive part; 113, first alignment structure; 2, circuit board; 21, binding part; 211, pin; 2111, first pin; 212, alignment pin; 213, second alignment structure; 22, reinforcement plate; 3, conductive adhesive layer; 4, first side wall; 5, second side wall; 6, hot pressing head. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0047] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be the usual meanings understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0048] There are two main structures of existing large-size flexible printed circuits (Flexible Printed Circuit, FPC): one is that the binding part is continuous without disconnection (such as Figure 1a The other is to disconnect between adjacent binding parts, and the two binding parts form a "U" shape (see Figure 1b shown).

[0049] In display products, such as Figure 1c As shown, the flexible circuit board 01 needs to be bound and connected with the substrate 02. Specifically, the gold fingers 011 in the binding area of ​​the flexible circuit board need to be aligned with the conductive contacts 03 in the binding area of ​​the substrate 02, and then the binding and connection are performed through a hot pressing process.

[0050] When designing conventional large FPC for vehicles, the production binding process requirements must be met. When the FPC is bound to the glass, the temperature is high and the thermal expansion is obvious. The gold finger 011 (also called "pin") in the binding area needs to be pre-shrunk. Whether the binding is qualified is determined by the binding alignment offset a (i.e. the alignment offset between the FPC gold finger 011 and the conductive contact 03 of the glass), which should not exceed 1 / 2 of the width b of the FPC gold finger 011. If it is less than 1 / 2 of b, the binding is considered qualified.

[0051] There are basically two pre-shrinkage design methods for disconnecting adjacent binding parts of existing large vehicle-mounted FPCs ("U" shape):

[0052] 1. Related "U" type large FPC design pre-shrinking method 1

[0053] The total distance from the 1st Pin (Pin) to the Nth Pin of the gold finger 011 of the single binding part of the FPC is pre-shrunk, and the center distance size of the two marking patterns (Mark) of the single binding part is controlled by tolerance, such as Figure 2a , Figure 2band Figure 2c shown.

[0054] In the figure, M1 is the center distance between the two marks of the left binding part A; M2 is the center distance between the two marks of the right binding part B; T pitch1 , T pitch2 It is the total pitch (i.e., total distance) from the 1st Pin to the Nth Pin of the gold finger 011 of a single binding part.

[0055] The dimensions M1 and M2 are the same as the center distance of the Mark on the glass substrate 02, and the conventional design tolerance is ±0.03mm.

[0056] T pitch1 , T pitch 2 The size after pre-shrinkage design needs to be made according to the pre-shrinkage ratio. The pre-shrinkage ratio is predetermined by the process based on project differences.

[0057] The shrink ratio refers to the ratio of the difference between the size of a single binding area of ​​the flexible circuit board before shrinking and the size after shrinking to the size before shrinking. The size before shrinking is designed according to the size corresponding to the binding area on the glass substrate 02, and then the size after shrinking is calculated based on the size before shrinking and the shrink ratio.

[0058] That is, T pitch1 =T pitch2 =P 1～N (i.e. the center distance from Pin1 to PinN on the glass) -P 1～N *Pre-shrinkage ratio.

[0059] The pre-shrinkage design is based on the fact that when the FPC is bound to the glass, the two binding parts (binding area A and binding area B) expand due to heat, while the reinforcement area M corresponding to the disconnected part between the binding parts A and B, as well as the reinforcement area L corresponding to the binding part A and the reinforcement area R corresponding to the binding part A do not expand.

[0060] In fact, the reinforcement area M, reinforcement area L and reinforcement area R undergo thermal expansion, which causes the first and last pins of the FPC to move outward to the left and right sides respectively, and the first and last pins deviate from the outside of the corresponding glass conductive contact sheet 03. At the same time, the outermost marks on the left and right sides of the FPC deviate from the glass conductive contact sheet 03 in the same direction. Figure 4

[0061] The actual alignment of FPC expansion by this pre-shrinking method has been verified through experiments. The defective rate of the offset (af, ae) greater than or equal to 1 / 2 of the width of the FPC gold finger 011 accounts for more than 30%.

[0062] Among them, af is the binding alignment offset between FPC and the first glass Pin, and ae is the binding alignment offset between FPC and the last glass Pin.

[0063] 2. Related "U" type large FPC design pre-shrinkage method 2

[0064] The FPC of this pre-shrinking method includes two pre-shrinking directions: a first pre-shrinking direction and a second pre-shrinking direction, see Figure 3a , Figure 3b and Figure 3c shown.

[0065] The FPC pre-shrinkage method includes two pre-shrinkage directions at the same time. The first pre-shrinkage direction is used for a single binding part, and the pre-shrinkage ratio is the same as the first pre-shrinkage method mentioned above. The total pitch (Ptotal) from the first pin f of the binding part A to the last pin e of the binding part B adopts the second pre-shrinkage direction, and the pre-shrinkage ratio is the same as the first pre-shrinkage direction. The center distance dimension of the two marks of a single binding part is controlled by tolerance, and the center distance dimension of the inner Mark B to Mark C is controlled by tolerance.

[0066] In the figure, M1 is the center distance between the two marks of the left binding part A, M2 is the center distance between the two marks of the right binding part B, M is the center distance between the inner Mark B and Mark C, T pitch1 , T pitch2 The total pitch of the gold finger 011 from the 1st pin to the Nth pin of a single binding part, P total It is the total distance from the first Pin (the leftmost gold finger 011) to the last Pin (the rightmost gold finger 011).

[0067] The center distance between M1, M2 and M is the same as that of the mark on the glass substrate 02, and the conventional design tolerance is ±0.03mm.

[0068] T pitch1 =T pitch2 =P 1～N (Center distance from Pin 1 to Pin N on the glass) -P 1～N *(0.0008~0.001).

[0069] P total =P pad (Center distance from the first pin conductive contact 03 to the last pin conductive contact 03 on the glass) -P pad *(0.0008~0.001).

[0070] The pre-shrinkage design is based on the following: in addition to the thermal expansion of the two binding parts of the FPC (binding part A and binding part B), the corresponding first and last pins of the entire FPC reinforcement plate are also pre-shrunk at the same time (corresponding to the second pre-shrinkage direction).

[0071] In this preshrinking method, the preshrinking ratio in the second preshrinking direction is the same as the preshrinking ratio in the first preshrinking direction.

[0072] The inventor has found through practice that pre-shrinking the FPC single section and the whole twice in the same period will cause the gold finger 011 to deviate greatly from the glass conductive contact 03 after the FPC is bound to the glass, and seriously deviate to the inside or outside of the conductive contact 03, so that the total number of effective conductive glue layer spheres at the binding point of the gold finger 011 is insufficient, the electrical conductivity is poor, and the potential risk of contact reliability is high, which affects the production yield, the production cost remains high, and the product revenue is low. Experiments show that after pre-shrinking the FPC single section and the whole twice in the same period, the FPC shrinks inward after actual alignment, and the defective rate of the offset greater than half of the width of the FPC gold finger 011 accounts for about 50%, and the offset is significantly increased.

[0073] After a large number of tests and verifications, the inventors found that the reason for the obvious increase in the offset is that the pre-shrinkage value in the second pre-shrinkage direction is much larger than the actual required amount. This is because when the FPC is bound by the hot pressing process, the temperature rise of the reinforcement plate and the binding part is different, and its temperature is much lower than the temperature of the binding part A and the binding part B. Therefore, if the same pre-shrinkage ratio is used for the single section and the whole FPC, the pre-shrinkage of the FPC will be too large, so that after the FPC is bound to the glass, the first Pin f and the last Pin e of the FPC will deviate to the inner side of the corresponding glass conductive contact 03 (that is, the FPC shrinks inward).

[0074] Based on this, see Figure 4 , Figure 5 and Figure 6 As shown, the present application provides a display module, in which the circuit board 2 and the display panel 1 are only preliminarily connected and have not been bound and connected through a hot pressing process. The various sizes of the circuit board 2 are the sizes before binding, that is, the sizes after pre-shrunk according to the design.

[0075] The display module comprises:

[0076] A display panel 1, wherein at least two binding areas 11 are provided on the display panel 1, and each of the binding areas 11 includes a plurality of conductive parts 111 arranged at intervals;

[0077] The circuit board 2 comprises at least two binding parts 21 arranged at intervals, each of the binding parts 21 comprises a plurality of pins 211 arranged at intervals, and the plurality of pins 211 of each binding part 21 correspond to and are connected to the plurality of conductive parts 111 of a binding area 11 one by one;

[0078] The distance between the first central axis of the first pin 2111 of each binding portion 21 and the second central axis of the binding portion 21 is the first distance, the distance between the third central axis of the first conductive portion 1111 of the binding area 11 corresponding to the binding portion 21 and the fourth central axis of the binding area 11 is the second distance, the first pin 2111 is the pin 211 far away from the first central axis among the plurality of pins 211, the first conductive portion 1111 is the conductive portion 111 corresponding to the first pin 2111, and the ratio of the difference between the second distance and the first distance to the second distance is the first pre-shrinkage ratio;

[0079] The distance between the second central axes of two adjacent binding portions 21 is a third distance, the distance between the fourth central axes of two adjacent binding areas 11 is a fourth distance, and the ratio of the difference between the fourth distance and the third distance to the fourth distance is a second pre-shrinkage ratio;

[0080] The first pre-shrinkage ratio is greater than the second pre-shrinkage ratio.

[0081] Specifically, at least two binding areas 11 are provided on the display panel 1 , and each of the binding areas 11 includes a plurality of conductive parts 111 arranged at intervals. The conductive parts 111 are made of conductive material and are used for binding and connecting with the circuit board 2 .

[0082] The circuit board 2 includes at least two binding parts 21 arranged at intervals, and the number of the binding parts 21 is the same as the number of the binding areas 11, so that the at least two binding parts 21 correspond to the at least two binding areas 11. Exemplarily, the circuit board 2 may be a flexible circuit board 2.

[0083] The circuit board 2 is further provided with a reinforcing plate 22, which is used as a base material to ensure the strength of the entire circuit board 2. The binding area 11 is provided on one side of the reinforcing plate 22, and the reinforcing plate 22 can support the binding area 11.

[0084] Each of the binding parts 21 includes a plurality of pins 211 arranged at intervals, and the plurality of pins 211 of each of the binding parts 21 correspond to and are connected to the plurality of conductive parts 111 of the binding area 11 one by one. The connection at this time is an initial connection, and is not bound by a hot pressing process. Therefore, the size of the circuit board 2 at this time is the size after pre-shrinking according to a pre-set pre-shrinking ratio before binding. The pre-shrinked circuit board 2 is connected to the display panel 1, and then hot-pressed by a hot pressing process. During the hot pressing process, the circuit board 2 will expand due to heat, thereby increasing the size of the circuit board 2.

[0085] Therefore, when the circuit board 2 is connected to the display panel 1, the size before binding is closely related to the size after binding. If you want to control the size after binding to meet the process requirements, then you must strictly control the size before binding to ensure that the offset between the circuit board 2 and the display panel 1 after binding meets the process requirements.

[0086] For specific implementation, see Figure 7 As shown, during the hot pressing process, the heated area of ​​the circuit board 2 is divided into two parts. The first heated area is the area where the binding portion 21 is located. The heating of this area will cause the binding portion 21 to move along the Figure 7 The second heated area is the area where the lower base of the binding part 21 is located. The heating of this area will cause the substrate to expand to both sides. The expansion of the substrate will drive the binding part 21 located on the substrate to expand along Figure 7 The second thermal expansion direction shown is expansion.

[0087] Therefore, when designing pre-shrinkage, it is necessary to consider the expansion in these two directions. Figure 8 As shown, when performing preset design, each binding portion 21 needs to be along Figure 8 The first pre-shrinking direction shown in the figure is pre-shrinked to correspond to the expansion of the binding portion 21 in the first heat expansion direction during the hot pressing process. In addition, two adjacent binding portions 21 need to be pre-shrinked along Figure 8 The second pre-shrinking direction shown is pre-shrinked to correspond to the expansion of the binding portion 21 in the first heat expansion direction during the hot pressing process.

[0088] Although the first preshrinkage direction and the second preshrinkage direction are determined, as mentioned above, if the preshrinkage ratio in the first preshrinkage direction and the second preshrinkage direction is not appropriate, it will cause the preshrinkage amount to be too large or too small, and ultimately cause the offset between the circuit board 2 and the display panel 1 after binding to be too large, which does not meet the process requirements.

[0089] Based on this, in the present application, the first pre-shrinkage ratio is controlled to be greater than the second pre-shrinkage ratio, wherein the first pre-shrinkage ratio is the pre-shrinkage ratio in the first pre-shrinkage direction, and the second pre-shrinkage ratio is the pre-shrinkage ratio in the second pre-shrinkage direction.

[0090] Specifically, see Fig. 9 , Fig.10 and Fig.11 As shown, the ratio of the difference between the second distance and the first distance and the second distance is the first pre-shrinkage ratio, wherein the first central axis (ie, Fig.11 ) and the second central axis of the binding portion 21 (i.e. Fig.11 The distance between them is the first distance (i.e. Fig.11The first pin 2111 is a pin 211 away from the first central axis among the plurality of pins 211. The pin 211 described in this embodiment is an effective pin 211 in the binding portion 21, that is, a pin 211 that plays an effective electrical connection role, and does not include a pin 211 used for alignment or a pin 211 used to assist in maintaining the uniformity of the binding portion 21.

[0091] The third central axis (i.e. Fig. 9 and Fig.10 ) and the fourth central axis of the binding region 11 (i.e. Fig. 9 and Fig.10 The distance between them is the second distance (i.e. Fig. 9 and Fig.10 The first conductive portion 1111 is a conductive portion 111 corresponding to the first pin 2111.

[0092] That is, the first distance is the distance between the first center axis of the first pin 2111 of each binding part 21 after pre-shrinkage and the second center axis of the binding part 21, and the second distance is the theoretical distance between the first center axis of the first pin 2111 of each binding part 21 and the second center axis of the binding part 21 before pre-shrinkage (that is, the relevant distance of the corresponding binding area 11).

[0093] The ratio of the difference between the fourth distance and the third distance to the fourth distance is the second pre-shrinkage ratio, wherein the second central axes (i.e. Fig.11 The distance between them is the third distance (i.e. Fig.11 The fourth central axis of two adjacent binding regions 11 (ie Fig. 9 and Fig.10 The distance between them is the fourth distance (i.e. Fig. 9 and Fig.10 ).

[0094] That is, the third distance is the distance between the second center axes of two adjacent binding parts 21 after pre-shrinkage, and the fourth distance is the theoretical distance between the second center axes of two adjacent binding parts 21 before pre-shrinkage (that is, the relevant distance of the corresponding binding area 11).

[0095] Since when the FPC is bound by a hot pressing process, the temperature rise of the reinforcement plate 22 (or substrate) and the binding part 21 is different, and the temperature of the reinforcement plate 22 is much lower than the temperature of the binding part 21, therefore, the expansion in the second thermal expansion direction is much smaller than the expansion in the first thermal expansion direction. Therefore, in the present application, controlling the first pre-shrinkage ratio to be greater than the second pre-shrinkage ratio can make the pre-shrinkage in the second pre-shrinkage direction smaller than the pre-shrinkage in the first pre-shrinkage direction during the pre-shrinkage design. In this way, the smaller pre-shrinkage in the second pre-shrinkage direction can just offset the smaller expansion in the second thermal expansion direction, and the larger pre-shrinkage in the first pre-shrinkage direction can just offset the larger expansion in the first thermal expansion direction, thereby making each pin 211 on the circuit board 2 accurately aligned with the corresponding conductive part 111 and bound and connected after hot pressing binding, thereby improving the binding alignment accuracy of the circuit board 2.

[0096] In addition, in the present application, the pins 211 are effective pins 211 in the binding part 21, that is, pins 211 that play an effective electrical connection role, and do not include pins 211 used for alignment or pins 211 used to assist in maintaining the uniformity of the binding part 21. When determining the pre-shrinkage amount and pre-shrinkage ratio, the central axis of the first pin 2111 is used as a reference to determine each distance. The first pin 2111 is the pin 211 farthest from the first central axis among the multiple pins 211 in a certain binding part 21, that is, the first pin 2111 is the first effective pin 211 or the last effective pin 211 in the binding part 21.

[0097] That is, when determining each distance, the reference used is the first effective pin 211 and the last effective pin 211 rather than the pin 211 used for alignment, which can improve the accuracy of the pre-shrinkage design and further improve the alignment accuracy.

[0098] This is because, during the actual test, what is tested is the alignment offset of the effective pin 211, rather than the alignment offset of the alignment pin 212. That is to say, the alignment offset of the alignment pin 212 cannot indicate whether the alignment binding is qualified or not. Therefore, in this application, the benchmark used is the first effective pin 211 and the last effective pin 211, rather than the alignment pin 212. This can improve the accuracy of the pre-shrinkage design and thus improve the alignment accuracy.

[0099] In some embodiments, the first pre-shrinkage ratio is 0.0008-0.001, and the second pre-shrinkage ratio is 0.0001-0.0003.

[0100] Specifically, the first pre-shrinkage ratio may be 0.0008, 0.0009, 0.001, etc. The second pre-shrinkage ratio may be 0.0001, 0.0002, 0.0003, etc.

[0101] When the first preshrinkage ratio and the second preshrinkage ratio are within this range, the preshrinkage amount in the first preshrinkage direction and the second preshrinkage direction are moderate, which can just offset the expansion amount in the second thermal expansion direction and the second thermal expansion direction, so that after hot pressing binding, each pin 211 on the circuit board 2 can be accurately aligned and bound with the corresponding conductive part 111, thereby improving the binding alignment accuracy of the circuit board 2.

[0102] In some embodiments, the distance P′ between the first central axes of the first pins 2111 of two adjacent binding portions 21 is calculated according to the following formula:

[0103] P′=P–(T 21 ×m1)–(D×m2)–(T 22 ×m1);

[0104] Wherein, P is the distance between the third central axes of the first conductive portions 1111 of two adjacent binding regions 11, T 21 is the second distance of one of the two adjacent binding areas 11, T 22 is the second distance of the other binding area 11 of the two adjacent binding areas 11, m1 is the first pre-shrinkage ratio, D is the fourth distance, and m2 is the second pre-shrinkage ratio.

[0105] Specifically, P is the third central axis (i.e. Fig.12 , that is, the theoretical distance between the first central axes of the first pins 2111 of two adjacent binding parts 21 before pre-shrinkage.

[0106] T 21 is the second distance of one of the two adjacent binding areas 11, that is, the theoretical first distance of the binding portion 21 corresponding to the binding area 11 before preshrinkage. m1 is the first preshrinkage ratio, T 21 ×m1 is the pre-shrinkage amount of one of the two adjacent binding portions 21 in the first pre-shrinkage direction.

[0107] Accordingly, T 22 ×m1 is the pre-shrinkage amount of the other binding portion 21 of the two adjacent binding portions 21 in the first pre-shrinkage direction.

[0108] D is the fourth distance, that is, the theoretical third distance before pre-shrinkage, m2 is the second pre-shrinkage ratio, and D×m2 is the overall pre-shrinkage amount of the two binding parts 21 in the second pre-shrinkage direction.

[0109] Therefore, P–(T 21 ×m1)–(D×m2)–(T 22×m1) represents the distance between the two binding parts 21 before pre-shrinking minus the pre-shrinkage amount in the first pre-shrinking direction and the pre-shrinkage amount in the second pre-shrinking direction, and the final value is the distance between the two binding parts 21 after pre-shrinking.

[0110] In the present application, determining the distance P′ between the first center axes of the first pins 2111 of two adjacent binding parts 21 based on the specific first pre-shrinkage ratio and the second pre-shrinkage ratio, as well as the second distance and the fourth distance can effectively improve the accuracy of the finally determined P′, thereby improving the alignment accuracy.

[0111] In some embodiments, see Fig. 9 As shown, each of the binding parts 21 also includes at least two alignment pins 212, and at least two of the alignment pins 212 are respectively located on both sides of the multiple pins 211; each of the binding areas 11 also includes at least two alignment conductive parts 112, and at least two of the alignment conductive parts 112 are respectively located on both sides of the multiple conductive parts 111, and each of the alignment conductive parts 112 corresponds to a alignment pin 212.

[0112] Specifically, the alignment pin 212 is used as an alignment mark, which is not connected to the circuit and is only used to assist in alignment. The alignment conductive block is arranged corresponding to the alignment pin 212, and the alignment of the alignment conductive block and the alignment pin 212 is used to assist the pin 211 and the corresponding conductive part 111 to accurately align.

[0113] Each of the binding parts 21 includes at least two alignment pins 212, and at least two of the alignment pins 212 are respectively located on both sides of the multiple pins 211. Each of the binding areas 11 also includes at least two alignment conductive parts 112, and at least two of the alignment conductive parts 112 are respectively located on both sides of the multiple conductive parts 111. In this way, the area where the multiple pins 211 and the multiple conductive parts 111 are located is called an alignment area. The alignment of each of the alignment pins 212 and the corresponding alignment conductive blocks can assist in the alignment of one side of the alignment area. The simultaneous alignment of the two alignment pins 212 and the corresponding alignment conductive blocks can assist in the positioning of both sides of the alignment area at the same time, thereby improving the alignment accuracy.

[0114] In some embodiments, see Fig.10 and Fig.11As shown, each of the binding areas 11 also includes at least two first alignment structures 113, and at least two of the first alignment structures 113 are respectively located on the side of each of the alignment conductive parts 112 away from the fourth center axis; each of the binding parts 21 also includes at least two second alignment structures 213, and at least two of the second alignment structures 213 are respectively located on the side of each of the alignment pins 212 away from the second center axis, and each of the second alignment structures 213 corresponds to a first alignment structure 113.

[0115] Specifically, at least two of the first alignment structures 113 are respectively located on a side of each alignment conductive portion 112 away from the fourth central axis, that is, the first alignment structure 113 is located outside the alignment conductive portion 112. At least two of the second alignment structures 213 are respectively located on a side of each alignment pin 212 away from the second central axis, that is, the second alignment structure 213 is located outside the alignment pin 212. In this way, the distance between two adjacent first alignment structures 113 is greater than the distance between two adjacent alignment conductive portions 112, and the distance between two adjacent second alignment structures 213 is greater than the distance between two adjacent alignment pins 212.

[0116] For the alignment process, the alignment device has a higher grasping accuracy when automatically grasping two alignment marks that are farther apart, and thus the alignment accuracy of the two alignment marks can be controlled to be higher. Therefore, in the present application, in the actual alignment process, the alignment device has a better accuracy when grasping two adjacent first alignment structures 113, so that the second alignment structure 213 and the first alignment structure 113 can be accurately positioned, and thus the alignment accuracy between the plurality of pins 211 and the corresponding conductive parts 111 can be improved.

[0117] When the grasping device cannot accurately grasp the first alignment structure 113 due to special reasons (for example, the distance between the two first alignment structures 113 is too far, or the first alignment structure 113 is damaged, etc.), the second alignment structure 213 and the first alignment structure 113 cannot be accurately aligned. At this time, it is necessary to control the grasping device to grasp two adjacent alignment conductive parts 112 with a shorter distance to control the alignment pins 212 and the corresponding alignment conductive parts 112 to be accurately positioned, to ensure that under the premise that the first alignment structure 113 and the second alignment structure 213 cannot be accurately aligned, the alignment pins 212 and the corresponding alignment conductive parts 112 can still be accurately aligned, thereby improving the alignment accuracy between the circuit board 2 and the display panel 1.

[0118] The present application also provides a method for preparing a display module, comprising:

[0119] Step S100, providing a display panel 1, wherein at least two binding areas 11 are provided on the display panel 1, each of the binding areas 11 comprises a plurality of conductive parts 111 arranged at intervals, wherein a distance between a third central axis of a first conductive part 1111 of the binding area 11 and a fourth central axis of the binding area 11 is a second distance, and a distance between the fourth central axes of two adjacent binding areas 11 is a fourth distance;

[0120] Step S200, determining a first pre-shrinkage ratio and a second pre-shrinkage ratio of the circuit board 2, wherein the first pre-shrinkage ratio is greater than the second pre-shrinkage ratio, the circuit board 2 comprises at least two binding parts 21 arranged at intervals, and each of the binding parts 21 comprises a plurality of pins 211 arranged at intervals;

[0121] Step S300, determining the size of the circuit board 2 after pre-shrinking based on the first pre-shrinking ratio, the second pre-shrinking ratio, the second distance and the fourth distance, and obtaining the pre-shrinking circuit board 2;

[0122] Step S400, align each binding portion 21 of the pre-shrunk circuit board 2 with a binding area 11 of the display panel 1, and bind and connect them through a hot pressing process, so that the multiple pins 211 of each binding portion 21 correspond to the multiple conductive portions 111 of a binding area 11 and are bound and connected one by one.

[0123] Specifically, when preparing the display module, a display panel 1 and a circuit board 2 need to be provided first.

[0124] See also Fig.13 As shown, at least two binding areas 11 are provided on the display panel 1, and each of the binding areas 11 includes a plurality of conductive parts 111 arranged at intervals, wherein the distance between the third center axis of the first conductive part 1111 of the binding area 11 and the fourth center axis of the binding area 11 is the second distance, and the distance between the fourth center axes of two adjacent binding areas 11 is the fourth distance.

[0125] like Fig.11 As shown, the circuit board 2 includes at least two binding parts 21 arranged at intervals, and each of the binding parts 21 includes a plurality of pins 211 arranged at intervals.

[0126] After providing the display panel 1 and the circuit board 2 , the circuit board 2 needs to be pre-shrunk to obtain a specific size of the pre-shrunk circuit board 2 .

[0127] Specifically, first, according to actual project requirements, determine the specific values ​​of the first pre-shrinkage ratio and the second pre-shrinkage ratio of the circuit board 2. In this embodiment, the first pre-shrinkage ratio is 0.0008-0.001, and the second pre-shrinkage ratio is 0.0001-0.0003.

[0128] Secondly, based on the first pre-shrinkage ratio, the second pre-shrinkage ratio, the second distance and the fourth distance, the size of the circuit board 2 after pre-shrinkage is determined.

[0129] Finally, after the pre-shrunk size of the circuit board 2 is determined, it is necessary to align and bind the circuit board 2 and the display panel 1. Specifically, each binding portion 21 of the pre-shrunk circuit board 2 is aligned with a binding area 11 of the display panel 1, and a binding connection is performed through a hot pressing process, so that the multiple pins 211 of each binding portion 21 correspond to the multiple conductive portions 111 of a binding area 11 one by one and are bound and connected.

[0130] In the present application, before pre-shrinking the circuit board 2, the first pre-shrinkage ratio and the second pre-shrinkage ratio are first determined according to actual needs, and then the pre-shrinked size of the circuit board 2 is determined based on the first pre-shrinkage ratio, the second pre-shrinkage ratio, the second distance and the fourth distance, and finally the pre-shrinked circuit board 2 is bound and connected to the display panel 1. Since the first pre-shrinkage ratio is controlled to be greater than the second pre-shrinkage ratio, the pre-shrinkage amount in the second pre-shrinkage direction is smaller than the pre-shrinkage amount in the first pre-shrinkage direction during the pre-shrinkage design, so that the smaller pre-shrinkage amount in the second pre-shrinkage direction can just offset the smaller expansion amount in the second thermal expansion direction, and the larger pre-shrinkage amount in the first pre-shrinkage direction can just offset the larger expansion amount in the first thermal expansion direction, so that after hot pressing binding, each pin 211 on the circuit board 2 can be accurately aligned and bound with the corresponding conductive part 111, thereby improving the binding alignment accuracy of the circuit board 2.

[0131] In some embodiments, determining the pre-shrunk size of the circuit board 2 based on the first pre-shrunk ratio, the second pre-shrunk ratio, the second distance, and the fourth distance includes:

[0132] Based on the first pre-shrinkage ratio, the second pre-shrinkage ratio, the second distance and the fourth distance, determine the first distance between the first center axis of the first pin 2111 of each binding part 21 of the circuit board 2 and the second center axis of the binding part 21, and the distance between the first center axes of the first pin 2111 of two adjacent binding parts 21 to determine the pre-shrinkage size of the circuit board 2.

[0133] Specifically, see Fig.11 As shown, to determine the pre-shrinked size of the circuit board 2, it is necessary to determine the specific sizes of the following three parts, so as to finally determine the accurate pre-shrinked size of the circuit board 2. Specifically, it includes:

[0134] Part 1: The distance between the first pin 2111 and the edge of the circuit board 2. This part of the dimensions belongs to the industry standard and can be set according to the standard;

[0135] The second part: a first distance between the first central axis of the first pin 2111 of each of the binding portions 21 and the second central axis of the binding portion 21 (i.e. Fig.11 The first distance can be calculated based on the first pre-shrinkage ratio and the second distance. Specifically, the product of the second distance and the first pre-shrinkage ratio is determined as the pre-shrinkage distance, and the difference between the second distance and the pre-shrinkage distance is determined as the first distance, so that the first distance after pre-shrinkage can be determined.

[0136] The third part: the second distance between the second central axes of two adjacent binding parts 21 (i.e. Fig.11 The calculation of the second distance essentially requires determining the distance between two adjacent binding portions 21. Therefore, based on the determination of the first distance, if the distance between the first central axes of the first pins 2111 of the two adjacent binding portions 21 can be determined (i.e. Fig.11 ), then it is equivalent to determining the second distance.

[0137] Therefore, in the present application, based on the first pre-shrinkage ratio, the second pre-shrinkage ratio, the second distance and the fourth distance, the distance between the first central axes of the first pins 2111 of the two adjacent binding parts 21 of the circuit board 2 is determined. Specifically, the distance P′ between the first central axes of the first pins 2111 of the two adjacent binding parts 21 is calculated according to the following formula: P′=P–(T 21 ×m1)–(D×m2)–(T 22 ×m1);

[0138] Wherein, P is the distance between the third central axes of the first conductive portions 1111 of two adjacent binding regions 11, T 21 is the second distance of one of the two adjacent binding areas 11, T 22 is the second distance of the other binding area 11 of the two adjacent binding areas 11, m1 is the first pre-shrinkage ratio, D is the fourth distance, and m2 is the second pre-shrinkage ratio.

[0139] Specifically, P is the third central axis (i.e. Fig.12 , that is, the theoretical distance between the first central axes of the first pins 2111 of two adjacent binding parts 21 before pre-shrinkage.

[0140] T 21 is the second distance of one of the two adjacent binding areas 11, that is, the theoretical first distance of the binding portion 21 corresponding to the binding area 11 before preshrinkage. m1 is the first preshrinkage ratio, T 21 ×m1 is the pre-shrinkage amount of one of the two adjacent binding portions 21 in the first pre-shrinkage direction.

[0141] Accordingly, T 22 ×m1 is the pre-shrinkage amount of the other binding portion 21 of the two adjacent binding portions 21 in the first pre-shrinkage direction.

[0142] D is the fourth distance, that is, the theoretical third distance before pre-shrinkage, m2 is the second pre-shrinkage ratio, and D×m2 is the overall pre-shrinkage amount of the two binding parts 21 in the second pre-shrinkage direction.

[0143] Therefore, P–(T 21 ×m1)–(D×m2)–(T 22 ×m1) represents the distance between the two binding parts 21 before pre-shrinking minus the pre-shrinkage amount in the first pre-shrinking direction and the pre-shrinkage amount in the second pre-shrinking direction, and the final value is the distance between the two binding parts 21 after pre-shrinking.

[0144] In the present application, based on the first pre-shrinkage ratio, the second pre-shrinkage ratio, the second distance and the fourth distance, the first distance between the first center axis of the first pin 2111 of each binding part 21 of the circuit board 2 and the second center axis of the binding part 21, and the distance between the first center axes of the first pins 2111 of two adjacent binding parts 21 can be accurately determined. In this way, the dimensions of each part of the circuit board 2 can be accurately controlled, so that when the circuit board 2 is bound and connected to the display panel 1 through a hot pressing process, the thermal expansion amount of each part thereof is basically consistent with the pre-shrinkage amount, thereby improving the alignment accuracy of the circuit board 2 and the display panel 1.

[0145] In some embodiments, the method of aligning each binding portion 21 of the pre-shrunk circuit board 2 with a binding area 11 of the display panel 1 and binding and connecting them through a hot pressing process so that a plurality of pins 211 of each binding portion 21 and a plurality of conductive portions 111 of a binding area 11 correspond to each other one by one and are bound and connected includes:

[0146] Align each of the binding portions 21 with a binding area 11 so that the fifth central axis between two adjacent binding portions 21 at least partially overlaps with the sixth central axis of the corresponding two adjacent binding areas 11;

[0147] Each of the binding portions 21 is bound and connected to one of the binding areas 11 by a heat pressing process.

[0148] Specifically, the aligning of each of the binding parts 21 with a binding area 11 includes: aligning each of the second alignment structures 213 with a first alignment structure 113, and aligning each of the alignment pins 212 of the binding part 21 with the corresponding alignment conductive part 112 of the binding area 11, so that each of the binding parts 21 is aligned with a binding area 11. In this way, through the alignment between the first alignment structure 113 and the second alignment structure 213, and the alignment between the alignment pins 212 and the alignment conductive part 112, the alignment accuracy between each pin 211 and the corresponding alignment conductive part 112 can be improved, thereby improving the alignment accuracy between the circuit board 2 and the display panel 1.

[0149] In some embodiments, the step of binding each of the binding portions 21 to a binding area 11 by a heat pressing process includes:

[0150] A conductive adhesive layer 3 is provided between the binding portion 21 and the binding area 11;

[0151] After the binding part 21 and the binding area 11 are heated to a preset temperature, the binding part 21 and the binding area 11 are pressed together at a preset pressure so that the multiple pins 211 of each binding part 21 correspond to the multiple conductive parts 111 of a binding area 11 and are bound and connected one by one.

[0152] Specifically, see Fig.14 As shown, a conductive adhesive layer 3 is arranged between the binding part 21 and the binding area 11. After the binding part 21 and the binding area 11 are heated to a preset temperature, the binding part 21 and the binding area 11 are pressed together at a preset pressure so that the multiple pins 211 of each binding part 21 correspond one-to-one with the multiple conductive parts 111 of the binding area 11 and are bound and connected.

[0153] The preset temperature and the preset pressure are both conventional parameters in the hot pressing process of the circuit board 2 and the display panel 1 , and are not specifically limited here, and can be selected according to actual process parameters.

[0154] In some embodiments, after aligning each binding portion 21 of the pre-shrunk circuit board 2 with a binding area 11 of the display panel 1 and binding and connecting them through a hot pressing process, so that a plurality of pins 211 of each binding portion 21 correspond to a plurality of conductive portions 111 of a binding area 11 one by one and are bound and connected, the method further includes:

[0155] The side wall of the first pin 2111 away from the second center axis is the first side wall 4, and the side wall of the first conductive part 1111 corresponding to the first pin 2111 away from the second center axis is the second side wall 5. The distance between the first side wall 4 and the second side wall 5 in the first direction is less than half of the width of the first pin 2111, and the first direction is the width direction of the first pin.

[0156] Specifically, see Fig.15 and Fig.16 As shown, after numerous experimental verifications, after the pre-shrunk circuit board 2 described in the present application is bound and connected to the display panel 1, the distance between the first side wall 4 and the second side wall 5 in the first direction (i.e., the alignment offset between the first pin 2111 and the first conductive part 1111) is less than half of the width of the first pin 2111, indicating that the pre-shrunk size of the pre-shrunk circuit board 2 described in the present application is very accurately controlled, and the alignment offset after binding is small, which fully meets the alignment binding requirements.

[0157] In some embodiments, a vehicle-mounted "U"-shaped large FPC binding process structure is further discussed through specific embodiments, such as Fig.17 shown.

[0158] When the large FPC (i.e., the circuit board 2) is bound to the glass substrate (i.e., the display panel 1), the binding process of a single binding part 21 is the same as that of an ordinary small-size FPC. The FPC binding part 21 directly contacts the high-temperature thermal compression head 6 of the equipment. The thermal compression head 6 quickly heats and pressurizes the FPC binding part 21. The thickness of the FPC in the binding area 11 is only 0.07 mm, and it will expand rapidly when heated.

[0159] There is a conductive adhesive layer 3 (ACF for short) under the FPC, and below the ACF is a binding area 11 on the glass substrate. The conductive part 111 of the binding area 11 is made on the glass substrate (the thickness of the vehicle-mounted substrate is generally 0.25-0.5 mm).

[0160] During the hot pressing process of ACF, the pressed conductive rubber balls are crushed, and the conductive liquid after the crushed rubber balls will be connected to form a conductive layer. The more the conductive balls are crushed, the larger the area of ​​the conductive layer, the more reliable the connection between the pins 211 of the FPC and the conductive part 111 of the glass substrate, and the better the electrical conductivity.

[0161] The thickness of the display panel 1 is much thicker than that of the FPC. During the hot pressing process, the heat transfer order of the high-temperature hot pressing head 6 is: hot pressing head 6 cutting → FPC substrate → FPC pin 211 → ACF → conductive part 111 → single glass substrate. When the heat is transferred to the glass substrate, it is very small, and the temperature of the glass substrate basically does not change, so the glass substrate does not expand.

[0162] In some embodiments, a pre-shrinking method for improving the alignment accuracy of a vehicle-mounted "U"-shaped large FPC is further discussed through specific embodiments, such as Fig.18 shown.

[0163] The preshrinking method includes two preshrinking directions: a first preshrinking direction and a second preshrinking direction

[0164] First pre-shrinking direction: the effective pin of the gold finger of the single binding part 21 of the FPC (i.e., the first pin 2111) is pre-shrinked from both ends toward the center of the binding part 21;

[0165] Second pre-shrinking direction: The left binding part A and the right binding part B of the FPC are pre-shrinked toward the center (Center ling L0)

[0166] 1. Calculation of pre-shrinkage ratio:

[0167] (I) Shrinkage ratio of the first shrinkage direction (hereinafter referred to as “direction one”):

[0168] 1. Calculation of expansion in one direction:

[0169] The pre-shrinkage ratio depends on the actual hot pressing temperature of the production line. The hot pressing temperature is generally set to 180℃~190℃. Because the hot pressing head is relatively long, the temperature of the hot pressing head (the contact surface with the FPC) is only about 75℃. The thermal expansion of the FPC is calculated as follows: a=△L / (L×△T)

[0170] in:

[0171] a: FPC linear expansion coefficient. For example, the expansion coefficient of the FPC binding portion 21 is 16-18 ppm / °C.

[0172] △L: Expansion after temperature change

[0173] L: Length dimension affected by temperature changes

[0174] △T: temperature change value, the binding process is the temperature rise value, △T = hot press head lower knife temperature - room temperature ≈ 75-25 ≈ 50℃

[0175] ∴△L=a×△T×L=(16~18ppm / ℃)×50℃×L=(8E-4~9E-4)×L

[0176] Therefore, the expansion amount of the single binding portion 21 is 8 to 9 ten-thousandths (ie, 0.0008 to 0.0009) of the length.

[0177] 2. Direction 1 pre-shrinkage ratio:

[0178] The pre-shrinkage ratio of the FPC single binding part 21 is consistent with the actual binding expansion, that is, the length dimension of the FPC before binding must be pre-shrunk. The binding conditions of different devices are different. For example, the pre-shrinkage ratio of direction one is 0.0008 to 0.001.

[0179] (ii) Shrinkage ratio of the second shrinkage direction (hereinafter referred to as “direction 2”)

[0180] 1. Calculation of expansion in two directions:

[0181] Since the adjacent binding parts of the "U"-shaped large FPC are disconnected in the middle, the temperature of the hot press head is directly transferred to the binding part during binding. The heat in other areas outside the FPC binding part is conducted from the binding part within the FPC substrate. When the heat is transferred to the substrate at the bottom of the binding area, the substrate will expand after being heated, and the expansion at this point will cause the FPC pins to move to the left and right outside.

[0182] The FPC shape, material and structure of different projects are different. There is no fixed ratio for the expansion amount of the lower part of the FPC binding area, and there will be some differences due to different projects.

[0183] To obtain the specific expansion amount, process test verification is required to determine the change in the center distance between adjacent binding parts before and after binding △D 12 ,See Fig.19 and Fig. 20 shown.

[0184] △D 12 =D′ 12 –D 12

[0185] △D 12 : The change in the center distance between adjacent binding parts before and after binding

[0186] D 12 : The center distance between binding part A and binding part B before binding

[0187] D′ 12 : The center distance between binding part A and binding part B after binding

[0188] Process test verification: Make more than 20 samples and measure D 12 , D′ 12 The average value is △D 12。

[0189] Then, the expansion coefficient in direction 2 is a2 = △D 12 / D 12 .

[0190] 2. Pre-shrinkage ratio in direction 2:

[0191] From the process test verification results, the expansion coefficient of direction 2 can be obtained, and the size P from the first effective pin to the last effective pin of the FPC can be calculated. total The pre-shrinkage ratio is obtained to obtain the Total pitch P' after pre-shrinkage total , the pre-shrinkage ratio is composed of different pre-shrinkage ratios of multiple sizes, such as Fig.21 shown.

[0192] P total : The total pitch from the first pin to the last pin before FPC pre-shrinkage;

[0193] P′ total : The total pitch from the first pin to the last pin after FPC pre-shrinkage;

[0194] ∵P total =T A +D 12 +T B , T A Pre-shrinkage ratio = pre-shrinkage ratio in direction 1 (exemplarily, 0.8 to 10.000), D 12 Pre-shrinkage ratio = a2 = △D 12 / D 12 , T B Pre-shrinkage ratio = T A Pre-shrinkage ratio;

[0195] ∴P′ total =(T A -T A × direction - pre-shrinkage ratio) + (D 12 -D 12 ×a2)+(T B -T B × direction - pre-shrinkage ratio) = P total –(T A × direction - pre-shrinkage ratio) – (D 12 ×a2)–(T B × direction - pre-shrinkage ratio).

[0196] 2. Dimension calculation of a vehicle-mounted "U" shaped large FPC with improved alignment accuracy, see Fig. 22 shown.

[0197] ① Pre-shrinkage direction - dimension T pitch1 , T pitch2 calculate

[0198] FPC single binding part pre-shrinkage size:

[0199] T pitch1 , T pitch2: The total Pitch (Pitch is the distance or size) from the first valid Pin to the Nth valid Pin of the gold finger of a single binding part

[0200] T pitch1 =T pitch2 =P 1～N (Center distance from effective Pin 1 to effective Pin N on the glass) -P 1～N × Direction 1 pre-shrinkage ratio. For example, the direction 1 pre-shrinkage ratio is 0.0008, so Tpitch1 =T pitch2 =P 1～N -P 1～N ×0.0008.

[0201] Assume that P has been determined 1～N =34.2mm, then T pitch1 =T pitch2 =34.2–34.2×0.0008=34.1726mm.

[0202] ②Calculation of the second dimension P′total in the pre-shrinking direction

[0203] P′ total =P total –(T A × direction - pre-shrinkage ratio) – (D 12 ×a2)–(T B × direction - pre-shrinkage ratio).

[0204] P total : The total pitch from the effective first pin to the effective last pin before FPC pre-shrinkage;

[0205] P′ total : The total pitch from the effective first pin to the effective last pin after FPC pre-shrinkage;

[0206] T A : The distance from the first effective pin of the binding part A on the glass to the center line L1 of the binding part A;

[0207] T A =T B =1 / 2×P 1～N ;

[0208] D 12 : The center distance between the binding part A and the binding part B before binding;

[0209] Expansion coefficient a2: The pre-shrinkage ratio of the second dimension D12 in the pre-shrinkage direction, which is determined according to the process verification results of the actual project. For example, the expansion coefficient a2 is generally less than 0.03%.

[0210] 3. Calculation of effective first pin and last pin deviation tolerance

[0211] (I) Effective first pin and last pin center deviation δ1, δ2 tolerance

[0212] The maximum FPC deviation occurs on the effective first and last pins on the left and right outer sides. First, calculate the center deviation δ1 (effective first pin of the left binding part) and δ2 (effective last pin of the right binding part) between the first pin of the FPC and the first conductive part on the glass substrate. Fig.23 .

[0213] δ1=δ2=C1–C 1tft =C2–C 2tft , C1=C2=(P mark -P' total ) / 2

[0214] in:

[0215] δ1: The center deviation between the effective first pin of the FPC (i.e. the first pin at the leftmost end) and the corresponding conductive part;

[0216] δ2: The center deviation between the effective tail pin of the FPC (i.e. the first pin at the rightmost end) and the corresponding conductive part;

[0217] C1: The distance from the effective first pin of FPC to the outer mark on the left side of FPC (i.e. the second alignment structure), with a normal tolerance of ±0.02mm and an optimal tolerance of ±0.015mm;

[0218] C2: The distance from the effective tail pin of FPC to the outer mark on the right side of FPC. The tolerance is normally ±0.02mm and the best is ±0.015.

[0219] C 1tft : The distance from the effective first pin pad of the glass substrate (i.e. the first conductive part at the far left) to the outer mark on the left side of the glass (i.e. the first alignment structure), with a tolerance of ±0.004mm;

[0220] C 2tft : The distance from the effective tail pin pad of the glass substrate (i.e., the second conductive part at the far left) to the outer mark on the right side of the glass (i.e., the first alignment structure), with a tolerance of ±0.004mm;

[0221] P mark : The center distance between the left and right outer marks of the FPC (i.e., the second alignment structure) is theoretically the same as the center distance between the marks on the corresponding glass substrate (i.e., the first alignment structure);

[0222] P′ total : The total pitch from the effective first pin to the effective last pin after FPC pre-shrinkage.

[0223] ∴δ1=δ2=(C1±0.015)–(C 1tft ±0.004)=(C2±0.015)–(C 2tft ±0.004)=(C1–C 1tft )±0.019=(C2–C 2tft )±0.019mm.

[0224] The effective first pin and tail pin center deviation δ1, δ2 tolerance can be ±0.019mm.

[0225] (II) Effective first pin, tail pin and conductive part offset tolerance A dev1 , A dev2 ,See Fig.24 .

[0226] A dev1 =A dev2 =W / 2+δ1–W pad / 2; among them,

[0227] A dev1 : The offset distance between the effective first pin of the FPC and the corresponding first conductive part;

[0228] A dev2 : The offset distance between the effective tail pin of FPC and the corresponding first conductive part;

[0229] W: FPC effective Pin width, tolerance ±0.02mm;

[0230] δ1: The center deviation between the effective first pin of the FPC and the corresponding first conductive part;

[0231] W pad : Width of the first conductive part of the effective glass pin, tolerance ±0.002mm;

[0232] ∴A dev1 =W / 2+δ1–W pad / 2=(W±0.02) / 2+(δ1±0.019)+(W pad ±0.002) / 2=(W / 2±0.01)+(δ1±0.019)+(W pad / 2±0.001)=(W / 2+δ1–W pad / 2)±0.03mm

[0233] Therefore, the deviation tolerance of the effective head and tail pins of the FPC is ±0.03mm. That is to say, after the FPC design adopts the appropriate pre-shrinkage method and pre-shrinkage ratio, the thermal expansion during binding can make the FPC pins and the glass conductive parts accurately aligned, and the deviation fluctuation can be controlled within ±30um.

[0234] Car Glass Pad pitch ≥0.16mm, the gold finger width (W) of FPC design is half of Pitch, that is, W≥0.08mm,

[0235] The deviation is max 30um≤1 / 2W, so the FPC binding deviation meets the specifications.

[0236] 4. A vehicle-mounted "U"-shaped large FPC binding mark grabbing method and size control, see Fig.25 .

[0237] Based on the above pre-shrinkage design, the Mark needs to be captured in the following way to ensure that the binding alignment fluctuation is minimal.

[0238] Mark capture method:

[0239] There are two cameras for capturing Mark during binding, with priority given to the left outer Mark A and the right outer Mark D.

[0240] Dimension Control:

[0241] According to the above pre-shrinkage design, the following dimensions and their tolerances need to be controlled:

[0242] (1)P′ total : The total pitch from the effective first pin to the effective last pin after FPC pre-shrinkage;

[0243] (2) C1, C2: The distance from the effective first and last pins of the FPC to the center of the left and right outer marks of the FPC;

[0244] (3)P mark : The distance between the left and right outer centers of FPC;

[0245] (4)T pitch1 , T pitch2 : The total pitch of the first valid pin to the Nth valid pin of the gold finger of a single binding part;

[0246] (5) M1, M2: Total pitch of valid pins of a single binding unit.

[0247] In this application, a new method for improving the alignment accuracy is proposed to address the problem of serious misalignment of a large "U"-shaped FPC after it is bound to a glass substrate. This method can greatly improve the alignment accuracy, effectively increase the area of ​​the ACF conductive glue balls and the total number of conductive ball particles, improve electrical conductivity, production yield and FPC connection reliability, and significantly reduce production costs.

[0248] The distance between the left and right outer marks of the “U”-shaped large FPC is controlled by dimensional tolerance, which reduces the fluctuation range of the alignment mark during binding and improves the alignment accuracy.

[0249] The single binding part of the FPC expands after being bonded to the glass at high temperature, so the incoming FPC material is pre-shrunk first. The total distance from the leftmost to the rightmost effective pin of the FPC is obtained from the actual data after bonding from the process, the expansion coefficient relative to the center of the FPC is determined, and then the pre-shrinkage ratio of the FPC is calculated.

[0250] Controlling the dimensional tolerance of the single-segment FPC alignment mark to the pin closest to it can reduce the deviation fluctuation of the left and right outer pins.

[0251] Different FPC substrate materials, shapes, and structures will result in different pre-shrinkage ratios for the binding parts. The pre-shrinkage ratios for specific projects can be accurately calculated through process verification results.

[0252] The present application also provides a display device, comprising the display module described in any of the above embodiments.

[0253] The display device can be a product with an image display function, for example, it can be: a monitor, a television, a billboard, a digital photo frame, a laser printer with a display function, a telephone, a mobile phone, a personal digital assistant (PDA), a digital camera, a portable camcorder, a viewfinder, a navigator, a vehicle, a large-area wall, a home appliance, an information query device (such as business query equipment and monitors of e-government, banks, hospitals, power and other departments).

[0254] The display device has the technical effects described in any of the above embodiments, which will not be elaborated here.

[0255] It should be noted that the above describes some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the above embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0256] A person skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present application is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0257] The embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the present application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the protection scope of the present application.

Claims

1. A display module, It is characterized in that include: A display panel, wherein at least two binding areas are provided on the display panel, and each of the binding areas includes a plurality of conductive parts arranged at intervals; A circuit board, comprising at least two binding parts arranged at intervals, each of the binding parts comprising a plurality of pins arranged at intervals, and the plurality of pins of each binding part corresponding to and connected with the plurality of conductive parts of a binding area one by one; The distance between the first central axis of the first pin of each binding portion and the second central axis of the binding portion is the first distance, the distance between the third central axis of the first conductive portion of the binding area corresponding to the binding portion and the fourth central axis of the binding area is the second distance, the first pin is a pin far away from the first central axis among the plurality of pins, the first conductive portion is a conductive portion corresponding to the first pin, and the ratio of the difference between the second distance and the first distance to the second distance is the first pre-shrinkage ratio; The distance between the second central axes of two adjacent binding parts is a third distance, the distance between the fourth central axes of two adjacent binding areas is a fourth distance, and the ratio of the difference between the fourth distance and the third distance to the fourth distance is a second pre-shrinkage ratio; The first pre-shrinkage ratio is greater than the second pre-shrinkage ratio.

2. The display module according to claim 1, It is characterized in that The distance P′ between the first central axes of the first pins of two adjacent binding parts is calculated according to the following formula: P′=P–(T 21 ×m 1 )–(D×m 2 )–(T 22 ×m 1 ); Wherein, P is the distance between the third central axes of the first conductive portions of two adjacent binding regions, T 21 is the second distance of one of the two adjacent binding regions, T 22 is the second distance of the other binding area in the two adjacent binding areas, m 1 is the first pre-shrinkage ratio, D is the fourth distance, m 2 is the second pre-reduction ratio.

3. The display module according to claim 1, It is characterized in that The first pre-shrinkage ratio is 0.0008-0.001, and the second pre-shrinkage ratio is 0.0001-0.0003.

4. The display module according to claim 1, It is characterized in that Each of the binding parts also includes at least two alignment pins, and at least two of the alignment pins are respectively located on both sides of the multiple pins; each of the binding areas also includes at least two alignment conductive parts, and at least two of the alignment conductive parts are respectively located on both sides of the multiple conductive parts, and each of the alignment conductive parts corresponds to a alignment pin.

5. The display module according to claim 4, It is characterized in that Each of the binding regions further comprises at least two first alignment structures, and the at least two first alignment structures are respectively located on a side of each of the alignment conductive portions away from the fourth central axis; Each of the binding portions further includes at least two second alignment structures. The at least two second alignment structures are respectively located on a side of each alignment pin away from the second central axis. Each of the second alignment structures corresponds to one of the first alignment structures.

6. A method for preparing a display module, It is characterized in that include: A display panel is provided, wherein at least two binding areas are provided on the display panel, each of the binding areas comprises a plurality of conductive parts arranged at intervals, wherein a distance between a third central axis of a first conductive part of the binding area and a fourth central axis of the binding area is a second distance, and a distance between the fourth central axes of two adjacent binding areas is a fourth distance; Determine a first pre-shrinkage ratio and a second pre-shrinkage ratio of the circuit board, wherein the first pre-shrinkage ratio is greater than the second pre-shrinkage ratio; wherein the circuit board comprises at least two binding parts arranged at intervals, and each of the binding parts comprises a plurality of pins arranged at intervals; Based on the first pre-shrinkage ratio, the second pre-shrinkage ratio, the second distance and the fourth distance, determining a pre-shrinkage size of the circuit board to obtain a pre-shrinkage circuit board; Each binding part of the pre-shrunk circuit board is aligned with a binding area of ​​the display panel and is bound and connected by a hot pressing process, so that multiple pins of each binding part correspond to multiple conductive parts of a binding area one by one and are bound and connected.

7. The preparation method according to claim 6, It is characterized in that The step of determining the size of the circuit board after pre-shrinking based on the first pre-shrinking ratio, the second pre-shrinking ratio, the second distance, and the fourth distance includes: Based on the first pre-shrinkage ratio, the second pre-shrinkage ratio, the second distance and the fourth distance, determine the first distance between the first center axis of the first pin of each binding part of the circuit board and the second center axis of the binding part, and the distance between the first center axes of the first pins of two adjacent binding parts to determine the pre-shrinkage size of the circuit board.

8. The preparation method according to claim 7, It is characterized in that The step of determining a first distance between a first central axis of a first pin of each binding portion of the circuit board and a second central axis of the binding portion includes: The product of the second distance and the first pre-shrinkage ratio is determined as the pre-shrinkage distance; The difference between the second distance and the pre-shrinkage distance is determined as the first distance.

9. The preparation method according to claim 7, It is characterized in that The step of determining the distance between the first central axes of the first pins of two adjacent binding parts includes: The distance P′ between the first central axes of the first pins of two adjacent binding parts is calculated according to the following formula: P′=P–(T 21 ×m 1 )–(D×m 2 )–(T 22 ×m 1 ); Wherein, P is the distance between the third central axes of the first conductive portions of two adjacent binding regions, T 21 is the second distance of one of the two adjacent binding regions, T 22 is the second distance of the other binding area in the two adjacent binding areas, m 1 is the first pre-shrinkage ratio, D is the fourth distance, m 2 is the second pre-reduction ratio.

10. The preparation method according to claim 6, It is characterized in that The method of aligning each binding portion of the pre-shrunk circuit board with a binding area of ​​the display panel and binding and connecting them by a hot pressing process so that a plurality of pins of each binding portion correspond to a plurality of conductive portions of a binding area one by one and are bound and connected comprises: Aligning each of the binding portions with a binding area so that the fifth central axis between two adjacent binding portions at least partially overlaps with the sixth central axes of the corresponding two adjacent binding areas; Each of the binding parts is bound and connected to a binding area through a hot pressing process.

11. The preparation method according to claim 10, It is characterized in that Each of the binding portions further comprises at least two alignment pins, and at least two of the alignment pins are respectively located on both sides of the plurality of pins; each of the binding regions further comprises at least two alignment conductive portions, and at least two of the alignment conductive portions are respectively located on both sides of the plurality of conductive portions; Each of the binding regions further comprises at least two first alignment structures, and the at least two first alignment structures are respectively located on a side of each of the alignment conductive portions away from the fourth central axis; Each of the binding portions further comprises at least two second alignment structures, the at least two second alignment structures are respectively located on a side of each alignment pin away from the second central axis, and each of the second alignment structures corresponds to a first alignment structure; The step of aligning each of the binding portions with a binding area comprises: Each of the second alignment structures is aligned with a first alignment structure respectively, and each of the alignment pins of the binding part is aligned with the alignment conductive part of the corresponding binding area, so that each of the binding parts is aligned with a binding area.

12. The preparation method according to claim 11, It is characterized in that The step of binding each of the binding parts to a binding area by a hot pressing process comprises: Disposing a conductive adhesive layer between the binding portion and the binding area; After the binding part and the binding area are heated to a preset temperature, the binding part and the binding area are pressed together at a preset pressure so that the multiple pins of each binding part correspond to the multiple conductive parts of a binding area and are bound and connected one by one.

13. The preparation method according to claim 6, It is characterized in that After aligning each of the binding parts of the pre-shrunk circuit board with a binding area of ​​the display panel and binding and connecting them through a hot pressing process, so that a plurality of pins of each binding part correspond to a plurality of conductive parts of a binding area one by one and are bound and connected, the method further includes: The side wall of the first pin away from the second center axis is the first side wall, and the side wall of the first conductive part corresponding to the first pin away from the second center axis is the second side wall. The distance between the first side wall and the second side wall in the first direction is less than half of the width of the first pin, and the first direction is the width direction of the first pin.

14. A display device, It is characterized in that The invention comprises the display module according to any one of claims 1 to 5 or the display module prepared by the preparation method according to any one of claims 6 to 13.

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