Method for improving the flatness of a press

Abstract

The present application relates to printed circuit board pressing processing technical field, disclose a kind of processing method for improving pressing flatness.The method is laminated first prepreg on the board with copper circuit pattern and circuit gap and carries out first pressing, and the resin of first prepreg fills circuit gap;After first pressing, the glass cloth and surface resin of first prepreg are stripped, while the resin in circuit gap is retained;Then laminated second prepreg, and carries out second pressing in the state that resin is filled in circuit gap, so that the board is formed.The method fills circuit gap and board forming into two pressings, and removes the glass cloth and surface resin of first prepreg between two pressings, can improve board flatness while maintaining the filling state of circuit gap.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board lamination technology, and in particular to a processing method for improving lamination flatness. Background Technology

[0002] For boards with copper circuit patterns and gaps, resin is needed to fill the gaps during lamination. One existing method of resin filling involves first filling the gaps with sealing resin or ink, and then laminating with a thin prepreg.

[0003] However, because the filling resin or ink needs to meet requirements such as resin viscosity and filling characteristics, its dielectric constant and loss factor may be difficult to match with the electrical characteristics of the prepreg, which may affect the continuity of the product impedance. In addition, when using prepreg to press and fill the gaps in the circuit board, the resin protrusions formed by the filling may cause unevenness on the board surface, resulting in poor board flatness.

[0004] Therefore, there is an urgent need for a processing method that can improve the flatness of the board surface after board pressing while preserving the filling state of the line gaps, and reduce the impact of inconsistent electrical properties of different resins to overcome the above defects. Summary of the Invention

[0005] The purpose of this invention is to provide a processing method to improve the flatness of the lamination, so as to solve the technical problem that existing processing methods are unable to improve the flatness of the board surface after lamination while preserving the filling state of the line gaps.

[0006] To achieve this objective, the present invention adopts the following technical solution: This invention provides a processing method for improving the flatness of the pressed surface, which includes the following steps: S1. A first prepreg is laminated on a board with copper circuit patterns and circuit gaps, and the board with the first prepreg laminated is pressed for the first time so that the resin of the first prepreg fills the circuit gaps. S2. After the first pressing, peel off the fiberglass cloth and surface resin of the first semi-cured sheet, and retain the resin filled in the gap of the line by the first pressing. S3. After the peeling is completed, a second prepreg is stacked on the board, and while the gaps between the lines are kept filled with resin, the board with the second prepreg is pressed a second time to form the board.

[0007] In some embodiments, the thickness of the fiberglass cloth of the first prepreg is not less than the thickness of the 2116 specification fiberglass cloth, and the specification of the fiberglass cloth of the second prepreg is 106.

[0008] Specifically, the fiberglass cloth of the first semi-cured sheet has a specification of 2116.

[0009] Specifically, the fiberglass cloth of the first semi-cured sheet has a specification of 7628.

[0010] In some embodiments, the first prepreg and the second prepreg use the same resin type.

[0011] In some embodiments, step S2 involves peeling off the fiberglass cloth and surface resin from the first semi-cured sheet, specifically including: Use a utility knife to peel off the fiberglass cloth and surface resin of the first prepreg from the edge of the plate.

[0012] In some embodiments, step S2 involves peeling off the fiberglass cloth and surface resin from the first semi-cured sheet, specifically including: Peel and tear off the fiberglass cloth and surface resin of the first semi-cured sheet from the edge of the plate.

[0013] In some embodiments, after the peeling is completed and before the second prepreg is laminated, the following steps are further included: The plate is cleaned.

[0014] Specifically, cleaning the board includes: Ultrasonic water washing is used to remove debris from the plate.

[0015] Furthermore, after the ultrasonic water washing, the following steps are also included: The plates are cleaned and dried using a pre-pressing treatment process, which is a browning process.

[0016] Compared with the prior art, the present invention has the following beneficial effects: On the one hand, this invention fills the gaps in the circuit with resin from the first prepreg during the first pressing. While retaining the resin within the gaps, the fiberglass cloth and surface resin of the first prepreg are peeled off. Then, a second prepreg is used for a second pressing and molding process, separating the filling of the gaps from the forming of the board. This improves the flatness of the board surface while maintaining the filling of the gaps. On the other hand, in embodiments where the first and second prepregs use the same resin type, the impact of inconsistent electrical properties of different resins can be avoided or reduced.

[0017] The present invention has other features and advantages, which will be apparent from or will be set forth in detail in the accompanying drawings and the following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the overall steps of a processing method for improving the flatness of the pressed surface according to an embodiment of the present invention.

[0020] Figure 2 This is a logic flowchart of a processing method for improving the flatness of the pressing according to an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of the stacking of the first semi-cured sheet and the plate before the first pressing in an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram showing that after the first pressing in this embodiment of the invention, the gap between the lines is filled and a height difference is formed on the board surface.

[0023] Figure 5 This is a schematic diagram of peeling off the fiberglass cloth and surface resin while retaining the resin in the line gap in an embodiment of the present invention.

[0024] Figure 6 This is a schematic diagram of the stacking of the second semi-cured sheet and the plate before the second pressing in an embodiment of the present invention.

[0025] Figure 7 This is a schematic diagram of the plate forming and the improvement of plate surface flatness after the second pressing in an embodiment of the present invention.

[0026] Figure 8 This is a schematic diagram of the operation of peeling off the sheet from the side edge using a utility knife in an embodiment of the present invention.

[0027] Figure 9 This is a schematic diagram of the optional stacking of cushioning material and release material in an embodiment of the present invention. Detailed Implementation

[0028] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this application in detail, the following description, in conjunction with the listed specific embodiments and accompanying drawings, provides a detailed explanation. The embodiments described herein are merely illustrative of the technical solutions of this application and are therefore intended to limit the scope of protection of this application.

[0029] Please see Figures 1-9 The processing method for improving the flatness of the pressing in this embodiment is used to process a board 100 having a copper circuit pattern 110 and a circuit gap 120. Through two pressings and selective peeling between the two pressings, the filling of the circuit gap 120 and the forming of the board 100 are completed respectively.

[0030] In this process, the copper circuit patterns 110 on the board 100 form circuit gaps 120. During the processing, the first prepreg 130 is used to provide resin to fill the circuit gaps 120 during the first pressing, and the second prepreg 150 is used to complete the second pressing while retaining the filling state.

[0031] like Figure 1 As shown, the method of this embodiment includes steps S1, S2 and S3 in sequence. In step S1, the resin 140 fills the line gap 120. In step S2, the fiberglass cloth 131 and surface resin 132 of the first semi-cured sheet 130 are removed and the resin 140 in the line gap 120 is retained. In step S3, a second pressing is performed to form the board 100.

[0032] like Figure 2 As shown, based on the main process of steps S1 to S3, the following can also be added: the selection of the specifications of the first semi-cured sheet 130, the peeling method of the edge side 101 of the plate 100, the cleaning treatment after peeling, and the optional stacking used for the first pressing. Figure 2 The optional processing does not change the order of steps S1 to S3.

[0033] The following will describe in detail each step of the processing method for improving the flatness of the pressed surface in this embodiment.

[0034] S1. A first prepreg 130 is stacked on a board 100 having a copper circuit pattern 110 and a circuit gap 120, and the board 100 with the first prepreg 130 stacked is pressed for the first time, so that the resin of the first prepreg 130 fills the circuit gap 120.

[0035] It is understood that at the beginning of step S1, the board 100 has a formed copper circuit pattern 110, and a circuit gap 120 is left between adjacent copper circuit patterns 110. The first prepreg 130 is superimposed on the side of the board 100 with the copper circuit pattern 110, so that the first prepreg 130 corresponds to the area where the copper circuit pattern 110 and the circuit gap 120 are located.

[0036] Specifically, the first prepreg 130 includes fiberglass cloth 131 and resin. After the first prepreg 130 is stacked onto the board 100, its resin is located on the filling source side of the line gap 120. Therefore, during the first pressing, the first prepreg 130 can supply resin to the line gap 120.

[0037] like Figure 3 As shown, before the first pressing, the first prepreg 130 is stacked on the board 100, covering the copper circuit pattern 110 and the circuit gaps 120. It can be understood that this state is used to receive the first pressing, allowing the resin in the first prepreg 130 to enter the circuit gaps 120.

[0038] During lamination, the first prepreg 130 continuously covers the copper circuit pattern 110 and the area of ​​the line gap 120 defined by adjacent copper circuit patterns 110. This coverage relationship ensures that there is a resin source from the same first prepreg 130 above both the copper circuit pattern 110 and the line gap 120, thereby enabling the first lamination to form a continuous process action area around the filling of the line gap 120.

[0039] During the first lamination, the resin of the first semi-cured sheet 130 fills the gaps 120 between the copper circuit patterns 110. After the first lamination is completed, the gaps 120 are filled with the same resin 140, thus forming the resin 140-filled state that needs to be retained during the subsequent selective peeling process.

[0040] After resin 140 enters the line gap 120 from the side of the first prepreg 130, it occupies the space between adjacent copper line patterns 110. Thus, step S1 not only forms a bond between the first prepreg 130 and the board 100, but also forms resin 140 located inside the line gap 120 that can be retained separately during the subsequent peeling process, thereby providing a structural basis for step S2 to distinguish between the peeling target and the retention target.

[0041] In this embodiment, the first pressing serves to fill the line gap 120. The resin 140 formed at this stage is located within the line gap 120. Even if the fiberglass cloth 131 and surface resin 132 in the first semi-cured sheet 130 are subsequently removed, the resin 140 already formed within the line gap 120 will still be used for further processing.

[0042] At the end of the first pressing, the intermediate plate 100 has at least two distinguishable portions, including the fiberglass cloth 131 and surface resin 132 located on one side of the plate, and the resin 140 that has entered the line gap 120. The former portion is removed in step S2, while the latter portion remains in step S2. Performing selective peeling according to this positional relationship helps maintain the continuity of the filling formed in step S1.

[0043] like Figure 4 As shown, after the resin of the first semi-cured sheet 130 fills the gaps 120 between the copper circuit patterns 110, the resin protrusions formed by the filling can create a height difference on the board surface after the first pressing. Figure 4 The state shown is that of board 100 after the line gap 120 has been filled and before selective stripping is performed.

[0044] in, Figure 4 The interval indicated by the double arrows is represented by H. H is used to indicate the height difference between the higher and lower positions on the plate surface after the first pressing. This symbol is used to express a relative distance relationship and does not limit the specific value. Additionally... Figure 4 The height difference shown corresponds to the stage of the board surface state after the first pressing and glue filling are completed. Its technical meaning is to illustrate the state of the board 100 after subsequent selective peeling and second pressing.

[0045] In summary, the completion of the first pressing is marked by the formation of resin 140 filling the line gap 120 as the process handover point. The height difference on the board surface at this stage is left to be addressed by subsequent selective peeling and the second pressing process, and the final forming of the board 100 is not required to be completed simultaneously with the first pressing.

[0046] Furthermore, the prepreg can be distinguished according to the specifications of the fiberglass cloth 131 therein. The thicknesses of the fiberglass cloth 131 with specifications of 106, 1080, 2116 and 7628 are 1.3mil, 2.1mil, 3.7mil and 6.8mil respectively. The above specifications are used to illustrate the thickness relationship of the fiberglass cloth 131 in the prepreg involved in this embodiment.

[0047] Preferably, in this embodiment, the thickness of the fiberglass cloth 131 of the first prepreg 130 is not less than the thickness of the 2116 specification fiberglass cloth 131, and the specification of the fiberglass cloth 131 of the second prepreg 150 is 106. Thus, the specifications of the fiberglass cloth 131 of the prepreg used in the two pressing processes are different.

[0048] For example, the first prepreg 130 can be a prepreg with a fiberglass cloth 131 specification of 2116 or a prepreg with a fiberglass cloth 131 specification of 7628. Both of the above choices satisfy the relationship that the thickness of the fiberglass cloth 131 of the first prepreg 130 is not less than the thickness of the 2116 specification.

[0049] When the first prepreg 130 adopts specification 2116 or specification 7628, it is stacked and first pressed according to step S1, and the resin of the first prepreg 130 is used to fill the line gap 120. Specification 1080 is only used to illustrate the specification and thickness sequence of fiberglass cloth 131, and is not a specific alternative to the first prepreg 130 in this embodiment.

[0050] S2. After the first pressing, the fiberglass cloth 131 and surface resin 132 of the first semi-cured sheet 130 are peeled off, while the resin 140 filled in the line gap 120 by the first pressing is retained.

[0051] Step S2 follows the resin 140 filling state formed in step S1. The objects to be peeled in step S2 are the fiberglass cloth 131 and surface resin 132 of the first semi-cured sheet 130. It is worth noting that the resin 140 filled in the line gap 120 by the first pressing is not the object to be removed in this step. After selective peeling, this part of the resin 140 is still left on the board 100.

[0052] like Figure 5 As shown, after the peeling is completed, the fiberglass cloth 131 and surface resin 132 of the first semi-cured sheet 130 have been removed from the surface of the board 100, while the line gaps 120 between the copper circuit patterns 110 still retain the resin 140 filled in step S1. The peeled object and the retained object are distinguished by their role in this intermediate state.

[0053] It is understood that by retaining the resin 140 within the line gap 120, the filling result obtained in step S1 will not be removed along with the peeling of the fiberglass cloth 131 and the surface resin 132. The peeled board 100 therefore still has the resin 140 filling state of the line gap 120 for the second lamination and the second pressing.

[0054] Therefore, the peeling process includes both material removal and state preservation. Specifically, on the one hand, it removes the fiberglass cloth 131 and the surface resin 132 on its surface from the board 100, and on the other hand, it avoids taking away the resin 140 located inside the line gaps 120 as the same peeling layer. After peeling is completed, the copper circuit pattern 110 is still separated from each other by the resin 140 retained in the line gaps 120, forming a surface state for subsequent lamination.

[0055] In a specific operation, such as Figure 8As shown, the fiberglass cloth 131 and surface resin 132 of the first prepreg 130 can be peeled off from the edge side 101 of the board 100 using a utility knife 180. Figure 8 The central area of ​​the middle plate 100 is the delivery area, and the utility knife 180 is used to form a peeling part on the edge side 101 that allows for further peeling and tearing operations.

[0056] After peeling is completed, the fiberglass cloth 131 and surface resin 132 of the first prepreg 130 are peeled off from the edge side 101 of the plate 100 and torn off. This operation continues along the processing relationship starting from the edge, so that the fiberglass cloth 131 and surface resin 132 are removed from the surface of the plate 100.

[0057] Understandably, the utility knife 180 is used to create a peeling starting point at the edge 101 of the board 100. After creating the peeling starting point, the subsequent action involves peeling and tearing off the fiberglass cloth 131 and the surface resin 132, while continuously identifying the resin 140 within the line gaps 120 that should be retained during this process. Thus, edge peeling, continued peeling, and retention of resin 140 correspond to the starting point of the operation, the material removal process, and the intermediate state control, respectively.

[0058] The peeling and subsequent peeling and tearing constitute an interconnected operation process. In this process, the desired result is still the removal of the fiberglass cloth 131 and the surface resin 132, while retaining the resin 140 that was first pressed and filled in the line gap 120.

[0059] After step S2 is completed, the fiberglass cloth 131 and surface resin 132 on the surface of the board 100 have been removed, while the resin 140 in the line gaps 120 remains filled. The intermediate board 100 can then proceed to the cleaning process or be stacked with the second prepreg 150 according to the main process.

[0060] In one embodiment, after peeling is completed and before the second semi-cured sheet 150 is stacked, the plate 100 is cleaned. This cleaning is located between steps S2 and S3 and is an optional step for processing the peeled intermediate plate 100.

[0061] Specifically, ultrasonic water washing can be used to remove debris from the plate 100. The ultrasonic water washing is performed on the plate 100 after peeling and before the second semi-cured sheet 150 is laminated, thus forming a clear temporal relationship with the aforementioned selective peeling and subsequent second lamination.

[0062] After ultrasonic water washing, the plate 100 is cleaned and dried using a pre-lamination process, which is a browning process. Both cleaning and drying are completed before the second semi-cured sheet 150 is laminated.

[0063] After cleaning and drying, the board 100 continues to be filled with resin 140 within the line gaps 120 and proceeds to step S3. It is worth noting that if the aforementioned optional cleaning treatment is not used, the board 100 after selective peeling is also laminated with the second prepreg 150 according to step S3.

[0064] Furthermore, the cleaning process targets the debris remaining on board 100 after selective peeling and the board surface condition before lamination, rather than reforming the filling of the line gaps 120. After ultrasonic water washing, browning cleaning, and drying, the retention relationship of resin 140 within the line gaps 120 continues to be maintained. Therefore, the cleaning and direct lamination paths have a consistent core board 100 state when entering step S3.

[0065] S3. After peeling is completed, a second prepreg 150 is stacked on the board 100, and the board 100 with the second prepreg 150 is pressed a second time while the line gap 120 is filled with resin 140, so that the board 100 is formed.

[0066] like Figure 6 As shown, before the second pressing, a second prepreg 150 is stacked on the plate 100 containing resin 140, and the gaps 120 between the copper circuit patterns 110 remain filled. The fiberglass cloth 131 of the second prepreg 150 has a specification of 106, and its stacking is based on the resin 140 filling state that was formed in step S1 and retained in step S2.

[0067] It is also understandable that, in terms of spatial correspondence, the second prepreg 150 covers the board surface that has undergone selective peeling, and together with the resin 140 retained in the line gap 120, they form an overlap state before the second lamination. Since the line gap 120 has been maintained filled with resin 140 when entering step S3, the second lamination does not change the source of this filling. The second lamination continues to shape the board 100 and improve the flatness of the board surface in this intermediate state.

[0068] In one embodiment, the first prepreg 130 and the second prepreg 150 use the same resin type. In this way, the resin 140 retained in the line gap 120 after the first pressing is the same type of resin as the prepreg used in the second pressing, so as to avoid or reduce the impact of inconsistent electrical properties of different resins.

[0069] Understandably, the first lamination focuses on filling the line gaps 120 with the resin of the first semi-cured sheet 130, while the second lamination completes the forming of the board 100 after the line gaps 120 have been filled with resin 140. The two laminations are connected by a selective peeling process in between and each performs its corresponding function.

[0070] During the second pressing, the second semi-cured sheet 150 and the plate 100, in which resin 140 is retained within the line gap 120, are pressed together, so that the plate 100 forms the molded state after the second pressing. Figure 7 As shown, with Figure 4 Compared to the height difference shown after the first pressing, the flatness of the board surface is improved after the second pressing.

[0071] After the second lamination is completed, the resin 140 within the line gaps 120 previously established by the first lamination and retained through selective peeling remains between the copper circuit patterns 110, and the second prepreg 150 forms a unified state with the board 100 after the second lamination. Since the filling of the line gaps 120 has been completed in the previous stage, the second lamination can further improve the board surface... Figure 4 The state shown has changed from a high-low elevation difference to a high-low elevation difference. Figure 7 The flatness shown is improved.

[0072] It should be noted that, as Figure 9 As shown, the first lamination can also use a material with better cushioning properties to prioritize filling the line gaps 120. Specifically, the corresponding stack can include a cushioning material 160, a release material 170, a first prepreg 130, and a board 100 with copper circuit patterns 110 and line gaps 120. It should be noted that this stack is an optional implementation of the first lamination and does not change the main process of steps S1 to S3.

[0073] Combination Figures 1-9 On the one hand, the present invention fills the line gap 120 with resin from the first prepreg 130 through a first pressing, while retaining the resin 140 within the line gap 120, and peeling off the fiberglass cloth 131 and surface resin 132 from the first prepreg 130. Then, a second pressing is performed using the second prepreg 150, separating the filling of the line gap 120 from the molding of the board 100, thereby improving the flatness of the board surface while maintaining the filling state of the line gap 120. On the other hand, in embodiments where the first prepreg 130 and the second prepreg 150 use the same resin type, the influence caused by the inconsistency of electrical properties of different resins can be avoided or reduced.

[0074] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A processing method for improving the flatness of pressing, characterized in that, Includes the following steps: A first prepreg is laminated onto a board with copper circuit patterns and gaps, and the board with the first prepreg laminated is pressed for the first time so that the resin of the first prepreg fills the gaps in the circuit. After the first pressing, the fiberglass cloth and surface resin of the first prepreg are peeled off, while the resin filled in the gap of the circuit by the first pressing is retained; After the peeling is completed, a second prepreg is laminated onto the board, and while the gaps between the lines are still filled with the resin, the board with the second prepreg laminated is pressed a second time to shape the board.

2. The processing method for improving the flatness of the pressed surface as described in claim 1, characterized in that, The thickness of the fiberglass cloth of the first semi-cured sheet is not less than the thickness of the 2116 specification fiberglass cloth, and the specification of the fiberglass cloth of the second semi-cured sheet is 106.

3. The processing method for improving the flatness of the pressed surface as described in claim 2, characterized in that, The fiberglass cloth specification of the first semi-cured sheet is 2116.

4. The processing method for improving the flatness of pressing as described in claim 2, characterized in that, The fiberglass cloth specification of the first semi-cured sheet is 7628.

5. The processing method for improving the flatness of the pressed surface as described in claim 1, characterized in that, The first prepreg and the second prepreg use the same resin type.

6. The processing method for improving the flatness of pressing as described in claim 1, characterized in that, The process of peeling off the fiberglass cloth and surface resin of the first semi-cured sheet specifically includes: Use a utility knife to peel off the fiberglass cloth and surface resin of the first prepreg from the edge of the plate.

7. The processing method for improving the flatness of the pressed surface as described in claim 1, characterized in that, The process of peeling off the fiberglass cloth and surface resin of the first semi-cured sheet specifically includes: Peel and tear off the fiberglass cloth and surface resin of the first semi-cured sheet from the edge of the plate.

8. The processing method for improving the flatness of pressing as described in claim 1, characterized in that, After the peeling is completed and before the second prepreg is laminated, the following steps are also included: The plate is cleaned.

9. The processing method for improving the flatness of pressing as described in claim 8, characterized in that, The cleaning of the aforementioned plates specifically includes: Ultrasonic water washing is used to remove debris from the plate.

10. The processing method for improving the flatness of the pressed surface as described in claim 9, characterized in that, Following the ultrasonic water washing, the following steps are also included: The plates are cleaned and dried using a pre-pressing treatment process, which is a browning process.

Images