A method for manufacturing a high-precision carbon oil resistor circuit board for automobiles

Abstract

The present invention discloses a method for manufacturing a high-precision carbon oil resistor circuit board for automobiles. The method comprises the following steps: taking a thick copper layer and a micro-stick film and attaching them to form an attached board, and making grooves on the attached board corresponding to the resistor pattern; the thickness of the thick copper layer is greater than the depth of the grooves; filling the grooves with carbon oil, and then performing a curing process to form a carbon oil pattern, and the entire board forms a carbon oil pattern board; taking a first single-sided copper-clad board and the carbon oil pattern board and pressing them together; the first single-sided copper-clad board and the carbon oil pattern are arranged relative to each other; removing the micro-stick film, performing a copper reduction process on the thick copper layer to expose the carbon oil pattern, and forming a carbon oil pattern double-sided board; then making a circuit pattern, and performing post-processing to form a circuit board; the carbon oil pattern made by the "reverse making" process has a much higher precision than traditional silk screen printing, which solves the problem that the manufacturing method of silk screen ink in the prior art easily produces the problem that the processing size of the carbon oil pattern is difficult to control, thereby causing the resistance value of the carbon oil pattern to exceed the standard.

Description

Technical Field

[0001] The present invention relates to the field of circuit board manufacturing, and in particular to a method for manufacturing a high-precision carbon oil resistor circuit board for a vehicle. Background Art

[0002] As the functions of products such as intelligent connected cars and low-altitude aircraft become more and more powerful, the requirements for the electronic modules of the control units used in them are also getting higher and higher. Due to limited installation space and the need to increase intelligent functions, the integration density of circuit boards is required to be higher. As a result, a method has emerged to replace the welded surface resistors with resistor patterns formed by processing the surface materials of the board (for example, making carbon oil patterns), thereby improving the integration density of the board.

[0003] The general production method of carbon oil graphics is similar to the processing method of silk screen ink. That is, the surface circuit pattern is first formed, and carbon oil is silk-screened at the location where the carbon oil pattern is required, and then baked and cured to form the carbon oil pattern.

[0004] However, there are the following defects:

[0005] (1) Since the carbon oil pattern needs to strictly control its pattern size, thereby controlling the resistance value of the carbon oil resistor, the screen printing carbon oil generally uses a screen with a mesh size of 43T to 71T. The mesh size cannot be too small, otherwise the amount of oil under the screen printing will be too large and difficult to control. The mesh size cannot be too large, otherwise the amount of oil under the screen printing will be too small and even clog the mesh.

[0006] However, for carbon oil pattern processing with high precision requirements, the size of the carbon oil pattern processed by the above-mentioned production method similar to silk screen ink is difficult to control, which easily leads to problems such as excessive resistance of the carbon oil pattern.

[0007] (2) The production of carbon oil graphics requires a lot of thermal baking processes, including: baking and curing after screen printing carbon oil, and pre-baking and post-baking curing during the screen printing surface solder mask process. Baking will have a great impact on the resistance of carbon oil resistors, making it difficult to ensure the stability of the resistance of carbon oil resistors.

[0008] Therefore, in order to solve the above-mentioned problems, it is necessary to provide a method for manufacturing a high-precision carbon oil resistor circuit board for automobiles. Summary of the Invention

[0009] The present invention aims to solve the comprehensive problem of low processing accuracy of silk-screen resistor patterns in the prior art, and proposes a method for manufacturing a high-precision carbon oil resistor circuit board for automobiles. The circuit board is processed according to design data, and the design data includes resistor patterns. The manufacturing method includes the following steps:

[0010] S10: Taking a thick copper layer and a micro-adhesive film and attaching them to form an attached plate, and then making grooves in the attached plate corresponding to the resistor pattern to form a grooved plate; the thickness of the thick copper layer is greater than the depth of the groove;

[0011] S20: Filling the groove with carbon oil and then performing a curing process to form a carbon oil pattern, and the entire board becomes a carbon oil pattern board;

[0012] S30: Laminating a first single-sided copper clad laminate and the carbon oil patterned laminate to form a laminated laminate; the first single-sided copper clad laminate and the carbon oil patterned laminate are arranged opposite to each other;

[0013] S40: removing the micro-adhesive film, performing copper reduction treatment on the thick copper layer to expose the carbon oil pattern, forming a carbon oil pattern double-sided board, and then performing post-processing to form the circuit board.

[0014] Furthermore, forming the carbon oil graphic plate includes performing a first supplementary baking process after the curing process.

[0015] Furthermore, after the curing process, the edge of the carbon oil pattern is laser ablated.

[0016] Furthermore, making a groove corresponding to the resistor pattern includes pre-enlarging the side of the resistor pattern facing the surface circuit pattern to form a pre-enlarged area, and the overall resistor pattern forms a pre-enlarged resistor pattern; forming the groove plate includes: making a groove on the attached plate corresponding to the pre-enlarged resistor pattern to form the groove plate; forming the carbon oil pattern double-sided board includes: after removing the micro-viscosity film, sticking a dry film to the position of the carbon oil pattern corresponding to the pre-enlarged resistor pattern and the connected surface circuit pattern, and making a dry film pattern, and then performing copper reduction treatment on the thick copper layer; the area where the dry film pattern covers the pre-enlarged resistor pattern is the pre-enlarged area.

[0017] Furthermore, the thickness of the thick copper layer is 5 microns to 20 microns greater than the depth of the groove.

[0018] Furthermore, the filling of carbon oil includes: making a silk screen stencil having a screen pattern corresponding to the resistor pattern, and using the silk screen stencil to screen print carbon oil on the groove.

[0019] Furthermore, the curing process includes: first performing a pre-baking process, then performing a flattening process, and then performing baking and curing.

[0020] Furthermore, the post-processing includes taking a second single-sided copper clad laminate to form a graphic board; then taking a prepreg and a copper foil layer, stacking them with the carbon oil graphic double-sided board to form a stacked structure, then pressing them to form a laminated board, and molding them to form the circuit board; the stacked structure includes: stacking the carbon oil graphic double-sided board, the prepreg, the graphic board and the copper foil layer in sequence from top to bottom.

[0021] Furthermore, the forming of the laminated board includes arranging a first high-flow adhesive prepreg between the prepreg and the carbon oil pattern double-sided board, and then performing the pressing.

[0022] Furthermore, the stacked structure includes a second high-flow adhesive prepreg stacked between the graphic board and the copper foil layer.

[0023] Furthermore, the post-processing includes making a solder mask layer on the laminated board and then performing a second supplementary baking process.

[0024] The technical solution of the present invention mainly has the following beneficial effects:

[0025] Through the "reverse production" process, grooves are first made on the thick copper layer, and the grooves are filled to complete the high-precision production of the carbon oil pattern. Then, it is pressed with the single-sided copper clad laminate to "transfer" the carbon oil pattern to the insulating dielectric layer of the single-sided copper clad laminate. The grooves are processed through dry film exposure, etching and other processes, with a precision much higher than traditional silk screen printing. The filled carbon oil is constrained by the grooves and the size is relatively more accurate, ensuring the resistance accuracy of the carbon oil pattern. This solves the problem of silk screen carbon oil, which is easy to cause the processing size of the carbon oil pattern to be difficult to control, resulting in the carbon oil pattern exceeding the resistance standard.

[0026] Furthermore, the thickness of the thick copper layer is 5 to 20 microns thicker than the groove. On the one hand (optionally greater than 5 microns), this ensures that after the thick copper layer forms a groove, there is support for the carbon oil at the bottom, avoiding the problem of pattern offset caused by the soft texture of the micro-mucous membrane when screen printing carbon oil. At the same time, a physical barrier layer can be formed at the bottom of the groove, which cooperates with the close fit between the micro-mucous membrane and the thick copper layer to reduce the risk of oil leakage. On the other hand (optionally less than 20 microns), this avoids excessive increase in copper thickness, which will increase the difficulty of copper reduction processing in the subsequent process.

[0027] The resistor pattern is pre-enlarged, and grooves are made according to the pre-enlarged resistor pattern. A dry film is applied to make a dry film pattern. Then, copper is reduced so that the increased copper thickness at the dry film pattern position (the thick copper layer is thicker than the copper thickness in the groove) is retained. The increased copper thickness layer at this position can effectively cover the pre-enlarged area of ​​the pre-enlarged resistor pattern, forming an effect of the copper layer (of the surface circuit pattern) covering the carbon oil pattern. This effectively avoids the problems of gaps and poor contact between the surface circuit pattern and the carbon oil pattern caused by simple adjacent connection, thereby preventing problems such as unstable and inaccurate resistance values ​​of the carbon oil resistor.

[0028] Through two supplementary baking processes, the carbon oil can be ensured to be fully dried and the stress in the board can be effectively released, avoiding carbon oil pattern deformation or resistance instability caused by residual substances or stress concentration, thereby improving the stability and reliability of the product.

[0029] The overall process forms an effective coordination between the front and back, with process synergy. First, high-precision carbon oil graphics are produced through the "reverse production" process, and then the carbon oil graphics are further stabilized through supplementary baking. At the same time, this process can be extended to multi-layer boards, and the carbon oil graphics are buried inside through stacking and pressing to meet high-density integration requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0031] Figure 1 This is a physical picture of the carbon oil pattern processed by silk screen printing in the existing technology;

[0032] Figure 2 Schematic diagram of the process flow of an embodiment of the present invention;

[0033] Figure 3 is a schematic cross-sectional view of an attachment plate according to an embodiment of the present invention;

[0034] Figure 4 Schematic cross-sectional view of a groove plate according to an embodiment of the present invention;

[0035] Figure 5 is a schematic cross-sectional view of a carbon oil graphic plate according to an embodiment of the present invention;

[0036] Figure 6 is a schematic cross-sectional view of a pressed plate according to an embodiment of the present invention;

[0037] Figure 7 Schematic cross-sectional view of a copper reduction plate according to an embodiment of the present invention;

[0038] Figure 8 Schematic cross-sectional view of another copper-reducing plate according to an embodiment of the present invention;

[0039] Figure 9 Schematic cross-sectional view of a carbon-oil patterned double-sided board according to an embodiment of the present invention;

[0040] Figure 10 for Figure 9 Bottom view in the AA direction;

[0041] Figure 11 A physical image of a silk-screen carbon ink pattern produced in accordance with an embodiment of the present invention;

[0042] Figure 12 is a schematic cross-sectional view of a stacked structure according to an embodiment of the present invention;

[0043] Figure 13 is a schematic cross-sectional view of a laminated plate according to an embodiment of the present invention;

[0044] Figure 14 is a schematic cross-sectional view of a circuit board according to an embodiment of the present invention;

[0045] Figure 15 This is a resistance comparison chart of the circuit board of this embodiment using the existing technology production process and the two-step supplementary baking process.

[0046] Explanation of the accompanying numbers: 10, attached board; 1010, thick copper layer; 20, groove board; 2010, groove; 30, carbon oil pattern board; 3010, carbon oil pattern; 40, pressed board; 4010, first single-sided copper clad board; 50, reduced copper board; 50A, another reduced copper board; 5010, covered copper layer; 60, carbon oil pattern double-sided board; 6010, surface circuit pattern; 70, stacked structure; 7010, first high-flow adhesive prepreg; 7020, prepreg; 7030, second high-flow adhesive prepreg; 7040, pattern board; 7050, copper foil layer; 80, laminated board; 90, circuit board; 9010, solder mask; 100X, existing technology production process; 100A, two supplementary baking processes.

[0047] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, inside, outside, etc.) are only used to explain the relative position relationship and movement status of the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0050] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0051] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0052] Please refer to Figure 1 , Figure 1 This is a physical picture of the carbon oil pattern processed by silk screen printing technology.

[0053] The existing carbon oil pattern is screen-printed on the upper surface of the existing surface circuit pattern on both sides, which easily causes problems such as carbon oil edge peeling or scratching. In addition, the edges of the existing carbon oil pattern are irregular and the surface is uneven (uneven thickness), which makes it difficult to control the resistance value of the carbon oil resistor and it is difficult to form a high-precision carbon oil resistance value.

[0054] See also Figure 2 , Figure 2 Schematic diagram of the process flow of an embodiment of the present invention.

[0055] The manufacturing process of the embodiment of the present invention includes using Figure 2 The following will implement the various steps in the process Figure 2 Each step in the process is further explained step by step.

[0056] The circuit board 90 of this embodiment is processed according to the design data, which includes the resistor pattern. The manufacturing method includes the following steps:

[0057] See also Figure 3 and Figure 4 , Figure 3 is a schematic cross-sectional view of an attachment plate according to an embodiment of the present invention; Figure 4 Schematic cross-sectional view of a groove plate according to an embodiment of the present invention.

[0058] Step S10 : taking the thick copper layer 1010 and the micro-adhesive film 1020 and attaching them to form an attached board 10 , and then making a groove 2010 on the attached board 10 corresponding to the resistor pattern to form a grooved board 20 ; the thickness of the thick copper layer 1010 is greater than the depth of the groove 2010 .

[0059] In the circuit board design data, the copper layer for making the surface circuit pattern 6010 is thickened, and the thick copper layer 1010 is taken as the basic material and attached with a micro-adhesive film 1020 to form a stable attached board 10, which provides a processing basis for the subsequent precise production of the groove 2010 and also provides support for the subsequent silk screen printing carbon oil process.

[0060] Specifically, the micro-mucous film 1020 ensures the stable attachment of the thick copper layer 1010 and the micro-mucous film 1020 to form a stable attachment plate 10 through its adhesion properties. On the other hand, the micro-mucous film 1020 also provides a protective effect on the thick copper layer 1010, preventing the etching solution from corroding the other copper surface when making the groove 2010.

[0061] Furthermore, the thickness setting of the thick copper layer 1010 also includes the following functions:

[0062] On the one hand, since the adhesion strength of the micro-mucous membrane 1020 itself is limited, carbon oil can easily be pressed into the gap between the thick copper layer 1010 and the micro-mucous membrane 1020 due to pressure during the silk screen printing process, causing oil leakage defects and affecting the accuracy of the resistance value and circuit reliability. Therefore, the thickness design of the thick copper layer 1010 can form a physical barrier layer at the bottom of the groove 2010, and the close fit between the thick copper layer 1010 and the micro-mucous membrane 1020 can reduce the risk of oil leakage.

[0063] On the other hand, if the copper layer is thin and the rigid support force is insufficient, it is easy for the groove 2010 to be displaced due to force during silk screen printing, which in turn causes large deviations in the length, width and thickness of the carbon oil pattern 3010; therefore, by designing a thick copper layer 1010 and utilizing its relatively large rigid support force, a stable support is provided for the groove 2010, avoiding etching deformation or damage caused by the copper layer being too thin, and combined with the uniform adhesion distribution of the micro-mucous film 1020, the displacement of the groove 2010 can be effectively suppressed, ensuring high-precision alignment of the carbon oil pattern 3010 with the design pattern, and improving the processing accuracy and consistency of the carbon oil pattern 3010.

[0064] Optionally, the thickness of the thick copper layer 1010 is 5 micrometers to 20 micrometers greater than the depth of the groove 2010 .

[0065] That is, after etching to form the groove 2010, the remaining copper thickness is 5μm to 20μm. If the remainder is too thick (>20μm), the difficulty of copper reduction processing will increase significantly. If the remainder is too thin (<5μm), excessive etching may occur due to etching errors, resulting in insufficient support for the remaining copper thickness.

[0066] Please refer to Figure 5 , Figure 5 Schematic cross-sectional view of a carbon oil graphic plate according to an embodiment of the present invention.

[0067] Step S20 : ​​Filling the groove 2010 with carbon oil and then performing a curing process to form a carbon oil pattern 3010 , and forming the entire plate into a carbon oil pattern plate 30 .

[0068] It is worth noting that the resistance calculation formula of the resistor graph is: R=ρ×L / S=(ρ×L) / (D×H)where:

[0069] L is the length in mm;

[0070] ρ is the material resistivity, in Ω·mm;

[0071] S is the cross-sectional area in mm 2 ;

[0072] D is the resistor width in mm;

[0073] H is the thickness of the thin film resistor, in mm;

[0074] It can be seen that the length L, width D, and thickness H all affect the size of the resistor R.

[0075] Therefore, the three-dimensional dimensions of the resistor pattern need to be strictly controlled during processing to ensure the realization of high-precision resistance values. In this embodiment, the resistor pattern is designed as a groove 2010 structure, and a carbon oil pattern 3010 is formed by filling the groove 2010. Compared with the traditional silk screen printing process, the accuracy can be significantly improved, providing a precise graphic basis for silk screen printing carbon oil in the groove 2010, and also laying the foundation for the subsequent "reverse production" process.

[0076] Furthermore, filling the carbon oil includes: making a silk screen stencil having a stencil pattern corresponding to the resistor pattern, and silk screen printing the carbon oil on the groove 2010 using the silk screen stencil.

[0077] Since the groove 2010 is processed by a graphic transfer method (i.e., processing by dry film application, exposure, development, etching, and film stripping), the processing accuracy is higher than that of the traditional direct silk screen printing process on the board. Therefore, this embodiment first accurately controls the size of the groove 2010 by etching, and then, on this basis, the carbon oil is directionally filled into the groove 2010 through the mesh of the silk screen. The carbon oil is limited by the boundary constraints of the groove 2010 and gathers in the groove 2010, so that the processing accuracy of the carbon oil pattern 3010 is significantly improved.

[0078] Optionally, an aluminum sheet mesh or a copper sheet mesh is used for silk screen printing; specifically, an aluminum sheet or a copper sheet is taken, and a groove 2010 is made corresponding to the resistor pattern to form a windowed aluminum sheet or a windowed copper sheet, and then the windowed aluminum sheet or the windowed copper sheet is adhered to the mesh to form an aluminum sheet mesh or a copper sheet mesh; this can make the silk screen processing accuracy higher.

[0079] Optionally, the curing process includes pre-baking, flattening, and post-baking to make the carbon oil smoother, improve the accuracy of its thickness, and improve the resistance accuracy of the carbon oil pattern 3010.

[0080] Optionally, the flattening process is to lay a release film on one side of the carbon oil pattern 3010, flatten it with a laminator, and flatten it after pre-baking. On the one hand, pre-baking can make the carbon oil form a preliminary solidification to prevent excessive overflow or excessive adhesion of the carbon oil during flattening. On the other hand, the flattening process can ensure the flatness of the carbon oil and improve the thickness uniformity of the carbon oil pattern 3010.

[0081] Furthermore, forming the carbon oil pattern plate 30 includes performing a first supplementary baking process after the curing process.

[0082] Optionally, the maximum temperature of the first supplementary baking is 110° C. to 120° C., and the maximum temperature baking time is 20 minutes to 50 minutes.

[0083] By gradually increasing the temperature during the first supplementary baking and performing high-temperature baking, the moisture or solvent in the carbon oil can be fully evaporated, while removing the internal stress of the board, making the carbon oil pattern 3010 more stable and accurate. The relatively low baking temperature can prevent the board from being overbaked and causing problems such as delamination.

[0084] Furthermore, after the curing process, the edge of the carbon oil pattern 3010 is laser ablated.

[0085] Through laser ablation, the carbon oil overflowing from the edge is accurately removed, eliminating the problem of increased pattern width caused by carbon oil overflow, improving the processing accuracy of the carbon oil pattern 3010, and effectively avoiding the resistance value of the carbon oil pattern 3010 being affected by the processing accuracy.

[0086] Please refer to Figure 6 , Figure 6 Schematic cross-sectional view of a pressed plate according to an embodiment of the present invention.

[0087] Step S30 : laminating the first single-sided copper clad laminate 4010 and the carbon oil pattern plate 30 to form a laminated plate 40 ; the first single-sided copper clad laminate 4010 and the carbon oil pattern 3010 are arranged opposite to each other.

[0088] By pressing the first single-sided copper clad laminate 4010 and the carbon oil pattern 3010 correspondingly, and combining the subsequent process of reducing copper to expose the carbon oil pattern 3010, a "reverse production" process is formed. That is, the high-precision production of the carbon oil pattern 3010 is first completed on the thick copper layer 1010, and then the carbon oil pattern 3010 is "transferred" to the surface of the insulating dielectric layer of the first single-sided copper clad laminate 4010 through a pressing process. The dimensional accuracy of the produced carbon oil pattern 3010 is higher, and reliable precision control is also provided for resistor processing.

[0089] Optionally, a high-flow adhesive prepreg is provided between the first single-sided copper clad laminate 4010 and the carbon oil pattern plate 30 ; the thickness of the high-flow adhesive prepreg is 5 μm to 20 μm.

[0090] The high-flow prepreg has better fluidity during the lamination process, and thus can produce a greater buffering effect on the carbon oil pattern 3010, thereby preventing the carbon oil pattern 3010 from being crushed and improving the interlayer bonding strength.

[0091] Optionally, a pure glue layer is provided between the first single-sided copper clad laminate 4010 and the carbon oil pattern plate 30 ; the pure glue layer is an acrylic pure glue layer or an epoxy resin pure glue layer; and its function is the same as that of providing a high-flow adhesive prepreg.

[0092] Please refer to Figures 7 to 14 , Figure 7 Schematic cross-sectional view of a copper reduction plate according to an embodiment of the present invention; Figure 8 Schematic cross-sectional view of another copper-reducing plate according to an embodiment of the present invention; Figure 9 Schematic cross-sectional view of a carbon-oil patterned double-sided board according to an embodiment of the present invention; Figure 10 for Figure 9 Bottom view in the AA direction; Figure 11 A physical image of a silk-screen carbon ink pattern produced in accordance with an embodiment of the present invention; Figure 12 is a schematic cross-sectional view of a stacked structure according to an embodiment of the present invention; Figure 13 is a schematic cross-sectional view of a laminated plate according to an embodiment of the present invention; Figure 14 Schematic cross-sectional view of a circuit board according to an embodiment of the present invention.

[0093] Step S40: remove the micro-mucus film, perform copper reduction treatment on the thick copper layer 1010, expose the carbon oil pattern 3010, form a copper reduction board 50, form a carbon oil pattern double-sided board 60, and then make a surface circuit pattern 6010. After post-processing, a circuit board 90 is formed.

[0094] Furthermore, making a groove 2010 corresponding to the resistor pattern includes pre-enlarging the side of the resistor pattern facing the surface circuit pattern 6010 to form a pre-enlarged area, and the overall resistor pattern forms a pre-enlarged resistor pattern; forming a groove plate 20 includes: making a groove 2010 corresponding to the pre-enlarged resistor pattern on the attached board 10 to form a groove plate 20; forming a carbon oil pattern double-sided board 60 includes: after removing the micro-adhesive film 1020, sticking a dry film to the position of the carbon oil pattern 3010 corresponding to the pre-enlarged resistor pattern and the connected surface circuit pattern 6010, and making a dry film pattern, and then performing copper reduction treatment on the thick copper layer 1010 to form another copper reduction board 50A, and forming a covering copper layer 5010 at the position of the dry film pattern; the area where the dry film pattern covers the pre-enlarged resistor pattern is the pre-enlarged area.

[0095] The resistor pattern is pre-enlarged, and a groove 2010 is made according to the pre-enlarged resistor pattern. A dry film is applied to form a dry film pattern. Then, copper is reduced so that the increased copper thickness at the dry film pattern position (the thickness of the thick copper layer 1010 compared to the groove 2010) is retained. This allows the increased copper thickness layer at this position to effectively cover the pre-enlarged area of ​​the pre-enlarged resistor pattern, creating an effect where the copper layer (of the surface circuit pattern 6010) covers the carbon oil pattern 3010. This effectively avoids problems such as gaps and poor contact between the surface circuit pattern 6010 and the carbon oil pattern 3010 that would otherwise occur if they were simply adjacent to each other, thereby preventing problems such as unstable and inaccurate resistance values ​​of the carbon oil resistor.

[0096] Since copper is a good conductor and carbon oil is a conductor with resistance properties, the resistance of the copper surface circuit pattern 6010 can be ignored, while the carbon oil pattern has resistance. Therefore, the method of making the pattern of the copper layer 5010 covered with the copper layer after pre-enlargement will not affect the resistance value of the carbon oil.

[0097] Furthermore, the post-processing includes taking a second single-sided copper clad laminate to form a graphic board 7040; then taking a semi-cured sheet 7020 and a copper foil layer 7050, stacking them with the carbon oil graphic double-sided board 60 to form a stacked structure 70, and then pressing them together to form a laminated board 80, and molding them to form a circuit board 90; the stacked structure 70 includes: a carbon oil graphic double-sided board 60, a semi-cured sheet 7020, a graphic board 7040 and a copper foil layer 7050 stacked in sequence from top to bottom.

[0098] Furthermore, forming the laminated board 80 includes placing a first high-flow adhesive prepreg 7010 between the carbon oil pattern double-sided board 60 and the prepreg 7020, and then laminating them.

[0099] Furthermore, the stacked structure 70 includes a second high-flow adhesive prepreg 7030 stacked between the graphic board 7040 and the copper foil layer 7050 .

[0100] The adhesive content of the first high-flow adhesive prepreg 7010 and the second high-flow adhesive prepreg 7030 are both 65% to 80%.

[0101] A carbon oil pattern double-sided board 60, a first high-flow adhesive prepreg 7010, a prepreg 7020, a pattern board 7040, a second high-flow adhesive prepreg 7030 and a copper foil layer 7050 are stacked in sequence from top to bottom to form a final laminated board 80. The carbon oil pattern 3010 is buried inside by stacking and pressing, which can effectively avoid the risks of carbon oil falling off or scratching in traditional processes, while also meeting the needs of high-density integration.

[0102] Furthermore, the post-processing includes forming a solder resist layer 9010 on the laminated board 80 and then performing a second supplementary baking process.

[0103] The maximum temperature of the second supplementary baking is controlled at 110°C to 150°C, preferably 125°C, and the maximum temperature baking duration is 20 minutes to 60 minutes, which can effectively release the internal stress of the board and promote the full volatilization of the solvent or moisture in the board, thereby avoiding deformation of the carbon oil pattern 3010 or resistance fluctuation caused by residual substances or stress concentration, thereby significantly improving the structural stability of the board and the long-term reliability of the carbon oil pattern 3010.

[0104] Please refer to Figure 15 , Figure 15 This is a resistance comparison chart of the circuit board of this embodiment using the existing technology production process and the two-step supplementary baking process.

[0105] In the carbon oil resistance diagram of the existing technology production process 100X, the resistance is R X ,in:

[0106] S1X: Test the resistance after printing carbon ink and baking;

[0107] S2X: Test resistance after pre-baking the silk screen solder mask ink;

[0108] S3X: Test resistance after solder mask is baked and cured;

[0109] S4X: Test resistance of finished board.

[0110] In the carbon oil resistance diagram for the two supplementary baking processes at 100A, the resistance is R1, where:

[0111] S1: Test the resistance after printing carbon ink and baking;

[0112] S2: Test the resistance value after the first supplementary baking;

[0113] S3: Test the resistance value after pre-baking the silk screen solder mask ink;

[0114] S4: Test the resistance value after the solder mask is baked and cured;

[0115] S5: Test the resistance value after the second supplementary baking;

[0116] S6: Test the resistance of the finished board.

[0117] Obviously, the resistance value of the carbon oil resistor produced by the prior art manufacturing process 100X fluctuates greatly in each baking process, which is not conducive to the resistance stability control of the carbon oil resistor.

[0118] The resistance value of the carbon oil at 100A after two supplementary baking processes shows regular changes: the resistance value changes in a small range and has high stability. The fluctuation of the resistance value (S4 to S6) of the final finished board test is significantly reduced. It can be seen that the two supplementary baking processes can effectively improve the stability of the resistance value.

[0119] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's description and drawings, or direct / indirect applications in other related technical fields, within the scope of the present invention are included in the patent protection scope of the present invention.

Claims

1. A method for manufacturing a high-precision carbon oil resistor circuit board for automobiles, wherein the circuit board is processed according to design data, wherein the design data includes a resistor pattern, and wherein: The production method comprises the following steps: S10: taking a thick copper layer and a micro-adhesive film and attaching them to form an attached plate, and then making grooves in the attached plate corresponding to the resistor pattern to form a grooved plate; The thickness of the thick copper layer is greater than the depth of the groove; S20: Filling the groove with carbon oil and then performing a curing process to form a carbon oil pattern, and the entire board becomes a carbon oil pattern board; S30: Laminating the first single-sided copper clad laminate and the carbon oil patterned plate to form a laminated plate; The first single-sided copper clad laminate is arranged opposite to the carbon oil pattern; S40: removing the micro-adhesive film, performing copper reduction treatment on the thick copper layer to expose the carbon oil pattern, forming a carbon oil pattern double-sided board, then making a surface circuit pattern, and performing post-processing to form the circuit board; The post-processing includes taking the second single-sided copper clad laminate to form a patterned board; then taking the prepreg and the copper foil layer, stacking them with the carbon oil patterned double-sided board to form a stacked structure, then pressing them together to form a laminated board, and then forming it to form the circuit board; The stacking structure comprises: stacking the carbon oil pattern double-sided board, the prepreg, the pattern board and the copper foil layer in sequence from top to bottom; The forming of the groove corresponding to the resistor pattern includes pre-enlarging the side of the resistor pattern facing the surface circuit pattern to form a pre-enlarged area, and the entire resistor pattern forms a pre-enlarged resistor pattern; The forming of the groove plate includes: making a groove on the attachment plate corresponding to the pre-large resistor pattern to form the groove plate; The forming of the carbon oil pattern double-sided board includes: after removing the micro-sticky film, applying a dry film to the position of the carbon oil pattern corresponding to the pre-large resistor pattern and the connected surface circuit pattern, and making a dry film pattern, and then performing a copper reduction treatment on the thick copper layer; The area where the dry film pattern covers the pre-enlarged resistor pattern is the pre-enlarged area.

2. The method for manufacturing a high-precision carbon oil resistor circuit board for a vehicle according to claim 1, characterized in that: The forming of the carbon oil graphic plate includes performing a first supplementary baking process after the curing process.

3. The method for manufacturing a high-precision carbon oil resistor circuit board for a vehicle according to claim 1 or 2, characterized in that: After the curing process, the edge of the carbon oil pattern is laser ablated.

4. The method for manufacturing a high-precision carbon oil resistor circuit board for a vehicle according to claim 1, wherein: The thickness of the thick copper layer is 5 micrometers to 20 micrometers greater than the depth of the groove.

5. The method for manufacturing a high-precision carbon oil resistor circuit board for a vehicle according to claim 1, wherein: The curing process includes: pre-baking, flattening, and baking and curing.

6. The method for manufacturing a high-precision carbon oil resistor circuit board for a vehicle according to claim 1, wherein: The forming of the laminated board includes arranging a first high-flow adhesive prepreg between the prepreg and the carbon oil pattern double-sided board, and then performing the lamination.

7. The method for manufacturing a high-precision carbon oil resistor circuit board for a vehicle according to claim 1, wherein: The stacked structure includes a second high-flow adhesive prepreg stacked between the graphic board and the copper foil layer.

8. The method for manufacturing a high-precision carbon oil resistor circuit board for a vehicle according to claim 6, wherein: The post-processing includes forming a solder resist layer on the laminated board and then performing a second supplementary baking process.

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