Thick copper FCBGA packaging substrate and preparation method thereof

Abstract

Provided are a thick copper FCBGA package substrate and a preparation method, the thick copper FCBGA package substrate comprising: a resin substrate comprising a central resin substrate and side resin substrates, a plurality of side resin substrates being symmetrically attached to both sides of a single central resin substrate in a thickness direction, the thickness of the single central resin substrate being greater than the thickness of the single side resin substrate; the copper layer is in contact with the resin substrate, and the copper thickness value of the copper layer ranges from 15 microns to 50 microns; wherein the resin substrate is made of a bismaleimide triazine resin material or an epoxy resin material; the thermal expansion coefficient of the resin substrate ranges from 0.1 PPM / DEG C to 20 PPM / DEG C; the copper layer comprises a plated hole copper layer; the plated hole copper layer comprises tubular plated copper and annular copper layers, and the annular copper layers extend outwards in the radial direction at the two ends of the tubular plated copper; and the tubular plated copper penetrates through the central resin substrate. The prepared FCBGA substrate is high in rigidity, not prone to warping and good in size stability.

Description

Technical Field

[0001] The present application relates to the field of printed circuit boards, and in particular to a thick copper FCBGA packaging substrate and a preparation method thereof. Background Art

[0002] The flip chip ball grid array packaging substrate can be called FCBGA board (Flip Chip Ball Grid Array). FCBGA board is the substrate used for the most advanced chip packaging method in the current semiconductor packaging field. At present, in order to meet the rapidly increasing demand for chip input and output (I / O), the size of FCBGA board is getting larger and larger to meet the needs of carrying multiple heterogeneous bare chips or single larger bare chips at the same time.

[0003] At present, FCBGA boards mainly use bismaleimide triazine resin (full name in English: Bismaleimide Triazine, abbreviated as: BT) to make the core layer (Core) and Ajinomoto build-up film (full name in English: Ajinomoto Build-up Film, abbreviated as: ABF) to make the build-up layer (full name in English: Build-Up, abbreviated as: BU). Due to the different thermal expansion coefficients (CTE) and Young's modulus of each material (ABF material has a large CTE and a small Young's modulus), the substrate is prone to warping after the thermal processing process. This problem will become more prominent when the package size becomes larger. If the warping is too large, it will lead to poor welding when the bare chip is packaged with the FCBGA substrate or when the FCBGA substrate is mounted on the PCB board, resulting in poor reliability after the chip is packaged or mounted on the PCB board.

[0004] Limited by the thickness of ABF materials, when the copper thickness is thicker, more materials are needed to fill the gaps between the circuit patterns of the FCBGA package substrate. In addition, the CTE of ABF materials is large, and when the thickness is thicker, there are potential concerns about the reliability of the connection of the conductive microvias (Via), which limits the use of ABF materials using the semi-additive method (SAP) to produce FCBGA products with a copper thickness of more than 25um. This type of microvia is treated with full copper filling. The hole shape (opening circularity, size, and ratio of the bottom and top of the hole) is controlled by controlling the laser drilling conditions, and then the electroplating parameters are adapted to achieve full copper filling of this type of microvia. However, some high-current and high-voltage chips require the FCBGA substrate BU copper thickness to reach more than 25um to ensure that the chip can achieve the designed performance. Summary of the invention

[0005] This application is made in view of the state of the prior art mentioned above. In the first aspect, the purpose of this application is to provide a thick copper FCBGA package substrate. It includes: a resin substrate, including a central resin substrate and a side resin substrate, a plurality of side resin substrates are symmetrically attached to both sides of a single central resin substrate in the thickness direction, and the thickness of a single central resin substrate is greater than the thickness of a single side resin substrate; a copper layer, the copper layer is in contact with the resin substrate, and the copper thickness of the copper layer ranges from 15um to 50um; wherein, the resin substrate is made of bismaleimide triazine resin or epoxy resin; the thermal expansion coefficient of the resin substrate ranges from 0.1PPM / ℃ to 20PPM / ℃; the copper layer includes a plated-through copper layer; the plated-through copper layer includes a tubular copper plating and an annular copper layer, and the annular copper layer extends radially outward at both ends of the tubular copper plating; the tubular copper plating runs through the central resin substrate.

[0006] As a further improvement of the present application, the resin substrate contains glass fibers.

[0007] As a further improvement of the present application, the copper thickness of the copper layer ranges from 25um to 50um.

[0008] As a further improvement of the present application, the hollow portion of the tubular copper-plated substrate is filled with a sealing glue, and the sealing glue connects the two adjacent side resin substrates on both sides of the central resin substrate.

[0009] As a further improvement of the present application, the copper layer has a rough surface on a side facing away from the central resin substrate, and the rough surface is in concave-convex matching with the resin substrate in contact.

[0010] As a further improvement of the present application, the total number of layers of the resin substrate and the copper layer ranges from four to thirty layers.

[0011] As a further improvement of the present application, the copper layers are arranged in mirror symmetry on both sides of the central resin substrate in the thickness direction.

[0012] As a further improvement of the present application, the resin substrate is a flame retardant material with a grade code of FR-4.

[0013] As a further improvement of the present application, the opposite back surfaces of the two side resin substrates which are farthest apart are respectively covered with a solder resist ink layer.

[0014] As a further improvement of the present application, a prefabricated solder bump penetrates the solder resist ink layer, and the prefabricated solder bump is in contact with and connected to the copper layer.

[0015] In a second aspect, a thick copper FCBGA package substrate preparation method is provided, which is used to manufacture the thick copper FCBGA package substrate of the present application, comprising: intermediate steps, the intermediate steps comprising: step S7: roughening the surface of the copper layer, using chemical solution to roughen the surface of the copper layer to form a rough surface; step S8: pressing a resin substrate and copper foil made of bismaleimide triazine resin or epoxy resin with a thermal expansion coefficient between 0.1PPM / ℃ and 20PPM / ℃ on the surface after the roughening treatment; step S10: The method comprises the following steps: drilling holes on the surface of the resin substrate; step S11: performing a desmear treatment on the surface of the resin substrate; step S12: thinning the copper foil; step S13: forming a seed copper layer in the hole formed by the punching; step S14: applying a plating resist and exposing the pattern to light; step S15: developing; step S16: adjusting the electroplating parameters to perform pattern electroplating to form a target copper thickness + α copper thickness; step S17: stripping the plating resist; step S18: flash etching to form a build-up layer pattern; step S19: repeating the cycle of steps S7 to S18 until the designed number of build-up layers is obtained.

[0016] As a further improvement of the present application, the thickness of the copper foil in step S8 is in the range of 2um to 5um; the thickness of the copper foil after thinning in step S12 is in the range of 0.3um to 2um; and the α copper thickness in step S16 is in the range of 1um to 2um.

[0017] As a further improvement of the present application, the drilling in step S10 is laser drilling; the de-drilling treatment in step S11 is dry and / or wet de-drilling treatment; and there is also a step S9 between step S8 and step S10 in the intermediate step, in which pre-drilling treatment is performed, and step S9 includes selecting a laser source, controlling laser parameters, and adjusting a laser focal point.

[0018] As a further improvement of the present application, the intermediate step also includes a pre-step, and the pre-step includes: step S1: preparing a copper-clad laminate made of bismaleimide triazine resin material or epoxy resin material with a thermal expansion coefficient between 0.1PPM / ℃ and 20PPM / ℃ and a thickness between 0.10mm and 1.50mm, and heat-treating the copper-clad laminate to remove stress and moisture; step S2: forming interconnection holes that penetrate the copper-clad laminate by laser drilling and / or mechanical drilling; step S3: metalizing the interconnection holes by chemical copper plating or electroplating copper, and forming plated holes after copper plating; step S4: plugging the plated holes with resin; step S5: performing chemical copper plating and electroplating copper again until a copper cap is formed on the plated hole; step S6: forming a circuit pattern by applying a photosensitive film, exposing, developing, and etching.

[0019] As a further improvement of the present application, the intermediate step also includes a post-step, and the post-step includes: step S20: roughening the surface of the outermost resin substrate and the copper surface; step S21: applying dry film solder resist ink, or applying liquid solder resist ink by printing or spraying; step S22: leveling the ink and exposing it to light; step S23: developing; step S24: performing photothermal curing treatment; step S25: performing chemical nickel gold, chemical nickel palladium gold or chemical tin plating on the surface; step S26: dividing and dicing the thick copper FCBGA package substrate; step S27: planting balls or reflowing printed solder paste to form prefabricated solder bumps; step S28: further cutting the divided and diced thick copper FCBGA package substrate into single PCB board units; step S29: flattening the prefabricated solder bumps.

[0020] The beneficial effects of the thick copper FCBGA package substrate of the present application include: using bismaleimide triazine resin material (BT material) as the resin substrate, because the thermal expansion coefficient (CTE) of the BT material is smaller than that of the Ajinomoto laminated film (ABF) material, and the Young's modulus is larger than that of the Ajinomoto laminated film (ABF) material, and the thick copper circuit technology is used, so the FCBGA substrate prepared in this way is more rigid than the substrate with ABF structure. The overall structure is not easy to warp, has good dimensional stability and high reliability. It has good high thermal performance, thereby improving the bare core packaging or chip mounting yield. In addition, the thickness range of thick copper can be applied to the field of high current and high voltage chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 This is a diagram of the first half of an operation state of an embodiment of a thick copper FCBGA package substrate of the present application;

[0023] Figure 2 This is a diagram of the second half of an operation state of an embodiment of the thick copper FCBGA package substrate of the present application;

[0024] Figure 3 It is a structural schematic diagram of an implementation of a thick copper FCBGA package substrate of the present application;

[0025] Figure 4 yes Figure 3 A partial enlarged view of point A.

[0026] Description of Reference Numerals

[0027] 1-prefabricated solder bump; 2-solder resist ink layer; 31-first copper layer; 32-second copper layer; 33-third copper layer; 34-fourth copper layer; 35-fifth copper layer; 36-sixth copper layer; 37-trapezoidal copper layer; 38-tubular copper plating; 39-rough surface; 41-first resin substrate; 42-second resin substrate; 43-third resin substrate; 44-fourth resin substrate; 45-fifth resin substrate; 5-sealing glue. DETAILED DESCRIPTION

[0028] The exemplary embodiments of the present application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present application, and are not intended to exhaust all possible methods of the present application, nor to limit the scope of the present application.

[0029] See also Figure 3 , the embodiment of the present application provides a thick copper FCBGA package substrate. The thick copper FCBGA package substrate includes several resin substrates and several copper layers. The resin substrate includes a central resin substrate and a side resin substrate, and several side resin substrates are symmetrically attached to both sides of the thickness direction of a single central resin substrate, and the thickness of the single central resin substrate is greater than the thickness of the single side resin substrate. The resin substrate is made of bismaleimide triazine resin material or epoxy resin material. Bismaleimide triazine resin material is BT material, which generally refers to a high-performance substrate material used in the manufacture of PCB boards. In practical applications, BT material has a resin system with a triazine ring structure, which gives BT material higher heat resistance, moisture resistance and dimensional stability. From another perspective, BT material is also synthesized by bismaleimide (full name in English: Bismaleimide, abbreviated as: BMI) and cyanate ester (full name in English: cyanate ester, abbreviated as: CE). The resin substrate can also use a BT-like material, that is, a material that is thermally stable and has electrical properties similar to BT material. The coefficient of thermal expansion (CTE) of the BT material or BT-like material of the resin substrate is between 0.1 PPM / °C and 20 PPM / °C. The copper layer contacts the resin substrate, and the copper thickness of the copper layer ranges from 15 um to 50 um.

[0030] The resin substrate can also use FR-4 flame retardant material with similar thermal expansion coefficient (CTE) and elastic modulus performance as bismaleimide triazine resin material. FR-4 means that the resin material must be able to extinguish itself after burning. It is a composite material formed by epoxy resin, filler and glass fiber. Most bismaleimide triazine resin materials and epoxy resin materials meet the specifications of FR-4.

[0031] The copper layer includes a plated-through copper layer; the plated-through copper layer includes a tubular copper plating 38 and an annular copper layer, the annular copper layer radially extending outward at both ends of the tubular copper plating 38; the tubular copper plating 38 penetrates the central resin substrate. From the perspective of shape, the plated-through copper layer is a reel shape, and the English abbreviation of the plated-through hole is PTH.

[0032] In one embodiment, the resin substrate contains glass fibers, and the glass fibers may be arranged in a horizontal and vertical cross pattern in the resin substrate.

[0033] The copper thickness of the copper layer ranges from 25um to 50um; the thickness of the copper foil is thinned to 0.3um to 2um. The purpose of thinning the copper foil is to control the thickness of the bottom copper of the seed layer, and to match the etching amount of the flash etching process of the MSAP process, so as to achieve finer and higher precision circuits. Among them, the flash etching process is to quickly etch away the base copper of the seed layer. Among them, in terms of the realization of fine circuit technology of circuit boards, there are mainly two processes in the industry, MSAP and SAP. MSAP is the abbreviation of Modified Semi-Additive Process, and SAP is the abbreviation of Semi-Additive Process.

[0034] like Figure 4 As shown, the copper layer has a rough surface 39 on one side facing away from the central resin substrate, and the rough surface 39 achieves a concave-convex matching connection with the resin substrate in contact, and the rough surface 39 achieves sufficient surface contact with the resin substrate in contact.

[0035] In terms of the total number of layers, the total number of layers of the resin substrate and the copper layer ranges from four to thirty layers, and the copper layers are arranged in a mirror-symmetrical manner on both sides of the thickness direction of the central resin substrate. In a non-limiting example, the resin substrate has a total of five layers, and the number of side resin substrates is four; the copper layers extending parallel to the plane of the resin substrate have a total of six layers. Figure 3 As shown, along the thickness direction, the resin substrate includes a first resin substrate 41, a second resin substrate 42, a third resin substrate 43, a fourth resin substrate 44, and a fifth resin substrate 45 arranged in sequence. Along the thickness direction, according to the actual position of the layer, the copper layer includes a first copper layer 31, a second copper layer 32, a third copper layer 33, a fourth copper layer 34, a fifth copper layer 35, and a sixth copper layer 36 arranged in sequence. The annular copper layer belongs to the category of the third copper layer 33 or the fourth copper layer 34. When observed from a perspective perpendicular to the plane where the resin substrate is located, the contour of the annular copper layer is annular, and the inner circle of the annular copper layer is connected to the axial end of the tubular copper plating 38. At the same time, the third resin substrate 43 is the central resin substrate, and the first resin substrate 41, the second resin substrate 42, the fourth resin substrate 44, and the fifth resin substrate 45 are the side resin substrates.

[0036] In one embodiment, the hollow part of the tubular copper plating 38 is filled with a sealing adhesive 5, and the sealing adhesive 5 connects two side resin substrates adjacent to the central resin substrate. That is, the sealing adhesive 5 connects the second resin substrate 42 and the fourth resin substrate 44.

[0037] In one embodiment, the copper layer further includes a king-shaped copper layer combination, which includes three copper layers, and the three copper layers are sequentially connected by trapezoidal copper layers 37. The annular copper layer and one copper layer in the king-shaped copper layer combination jointly contact the same resin substrate. The first copper layer 31 is connected to the second copper layer 32 by a trapezoidal copper layer 37, and the second copper layer 32 is connected to the third copper layer 33 by another trapezoidal copper layer 37, finally forming a king-shaped copper layer combination. The fourth copper layer 34 is connected to the fifth copper layer 35 by a trapezoidal copper layer 37, and the fifth copper layer 35 is connected to the sixth copper layer 36 by another trapezoidal copper layer 37, finally also forming a king-shaped copper layer combination.

[0038] In one embodiment, a plurality of king-shaped copper layer combinations are distributed on both sides in the thickness direction of the central resin substrate in a mirror-symmetrical layout.

[0039] In one embodiment, solder mask layers 2 are covered on the opposite surfaces of the two side resin substrates that are farthest apart. That is, solder mask layers 2 are covered on the opposite surfaces of the first resin substrate 41 and the fifth resin substrate 45.

[0040] The solder mask layer 2 is penetrated with prefabricated solder bumps 1, and the prefabricated solder bumps 1 are in contact with the king-shaped copper layer combination. That is, the prefabricated solder bumps 1 are in contact with the first copper layer 31. The prefabricated solder bumps 1 facilitate the quick connection of the finished PCB board to other components.

[0041] This application also provides a preparation method for a thick copper FCBGA packaging substrate, which is used to solve the problems that the FCBGA packaging substrate with a monosodium glutamate laminated film (ABF) structure is prone to warping and it is not easy to achieve thick copper. The processes or steps of its preparation method are as follows:

[0042] (1) Refer to Figure 1 in state A, prepare a BT material or a BT-like material copper clad laminate with a coefficient of thermal expansion (CTE) between 0.1 PPM / °C and 20 PPM / °C and a thickness between 0.10 mm and 1.50 mm, and perform heat treatment on the copper clad laminate to remove stress and moisture;

[0043] (2) Refer to Figure 1 in state B, form interconnection holes penetrating the copper clad laminate by laser drilling or mechanical drilling. The interconnection holes can be formed by mechanical drilling or laser pair drilling; among them, necessary pretreatment is carried out before laser drilling, such as selecting a suitable laser source, controlling laser parameters, adjusting the laser focus point, a machine drill bit of appropriate material, controlling the machine drill processing speed, and using a baffle plate;

[0044] (3) See Figure 1 In state C, the interconnection hole is metallized by chemical copper plating or electrolytic copper plating, and the interconnection hole forms a plated-through hole (PTH) after copper plating;

[0045] (4) See Figure 1 In state D, the plated-through hole (PTH) is plugged with a special resin, dried, cured, and polished;

[0046] (5) If necessary, the plated hole (PTH) resin plugged substrate is subjected to chemical copper plating and electroplating again to form a copper cap on the plated hole (PTH); this process is optional. If the subsequent conductive microvia (Via) on the layer adjacent to the plated hole (PTH) needs to be prepared directly above the plated hole (PTH), it is necessary to make a copper cap for the plated hole (PTH) by copper plating. Otherwise, the conductive microvia (Via) will be punched on the resin in the middle of the plated hole (PTH), and electrical conduction cannot be achieved;

[0047] (6) See Figure 1 From state E to state I in the figure, a conductive circuit pattern is produced on the core material through a graphic process; that is, a circuit pattern is formed through a series of processing such as applying a photosensitive film, exposing, developing, and etching;

[0048] (7) See Figure 1 In the state J, the surface of the copper layer is roughened, and the surface and side of the copper layer contacted by the chemical solution are roughened to form a rough surface;

[0049] (8) See Figure 2 In state K, a BT or BT-like prepreg (PP) with a coefficient of thermal expansion (CTE) between 0.1PPM / ℃ and 20PPM / ℃ and an ultra-thin copper foil are pressed on the surface of the roughened product, and the thickness of the ultra-thin copper foil ranges from 2um to 5um;

[0050] (9) See Figure 2 In the state L, the surface is treated before laser drilling;

[0051] (10) The surface is laser punched;

[0052] (11) See Figure 2 In state M, the surface is subjected to dry and / or wet decontamination treatment, wherein dry decontamination treatment refers to plasma treatment, and wet decontamination treatment refers to the removal of burnt resin, debris, etc. caused by laser drilling by immersion in chemical solutions;

[0053] (12) See Figure 2 In state N, the copper foil is thinned to 0.3um to 2um;

[0054] (13) See Figure 2 In state O, chemical copper plating forms a seed copper layer on the inner wall of the hole. The seed copper layer is a thin copper film formed on the substrate through a specific process before electroplating. This copper film serves as the "seed" for the subsequent electroplating process, ensuring that the electroplated copper can be evenly and firmly attached to the substrate, improving adhesion;

[0055] (14) See Figure 2 In the states P and Q, the resist is applied and the pattern is exposed to light;

[0056] (15) See Figure 2 The state R in the development;

[0057] (16) See Figure 2 In the states S and T, the electroplating parameters are adjusted to perform pattern electroplating to form a target copper thickness + α copper thickness, and the α copper thickness value range can be selected from 1um to 2um;

[0058] (17) See Figure 2 In the state U, the anti-plating film is stripped off;

[0059] (18) See Figure 2 State V in the middle, flash erosion, forming a build-up layer (BU layer) pattern;

[0060] (19) See Figure 2 In the state W in the above process, the above process (7) to the process (18) are repeated until the designed number of build-up layers (BU layers) is obtained;

[0061] (20) roughening the outermost resin substrate and the copper surface to increase the bonding strength between the copper surface and the resin substrate and the solder resist ink;

[0062] (21) Apply dry film solder resist ink, or apply liquid solder resist ink by printing, spraying, etc.;

[0063] (22) The ink is leveled and exposed;

[0064] (23) Development;

[0065] (24) performing photothermal curing treatment;

[0066] (25) The surface is subjected to one of the following surface treatments: chemical nickel-gold, chemical nickel-palladium-gold, chemical tin plating, etc.;

[0067] (26) Cutting the entire thick copper FCBGA package substrate into small panels;

[0068] (27) Ball planting or printed solder paste reflow to form prefabricated solder bumps;

[0069] (28) Cutting into individual pieces, that is, the small panels are further cut into individual PCB board units;

[0070] (29) flattening the prefabricated solder bump;

[0071] Figure 3 yes Figure 2 For an enlarged view of state X, see Figure 2 State X in corresponds to step (20) to step (29).

[0072] The process characteristics of the preparation method are: starting from step (8), BT or BT-like materials are used, and the MSAP process with copper foil is adopted, instead of using ABF film materials and not using the SAP process without copper foil.

[0073] The beneficial effects of the thick copper FCBGA packaging substrate and the preparation method thereof of the present application include: providing a FCBGA packaging substrate with low warpage performance, and using BT and BT-like materials in the whole layer will improve the defect of substrate warpage, thereby improving the packaging yield, and improving the bare core packaging and chip mounting yield and reliability. The preparation of FCBGA with a copper thickness of 15um to 50um in the build-up layer (BU layer), especially the preparation of FCBGA with a copper thickness of 25um to 50um in the build-up layer (BU layer), meets the demand of high-current, high-voltage and high-power chips for FCBGA substrates, and thick copper can improve the heat dissipation, voltage drop and other performances in high-power application scenarios.

[0074] The above embodiments are only for illustrating the technical concept and features of the present application, and their purpose is to enable people familiar with this technology to understand the content of the present application and implement it. They cannot be used to limit the scope of protection of the present application. All equivalent changes or modifications made according to the spirit of the present application should be included in the scope of protection of the present application.

Claims

1. A thick copper FCBGA package substrate, characterized in that: include: A resin substrate, comprising a central resin substrate and side resin substrates, wherein a plurality of side resin substrates are symmetrically attached to both sides of a single central resin substrate in a thickness direction, and a thickness of a single central resin substrate is greater than a thickness of a single side resin substrate; A copper layer, the copper layer is in contact with the resin substrate, and the copper thickness of the copper layer ranges from 15um to 50um; The resin substrate is made of bismaleimide triazine resin or epoxy resin; the thermal expansion coefficient of the resin substrate ranges from 0.1 PPM / °C to 20 PPM / °C; the copper layer includes a plated-through copper layer; the plated-through copper layer includes a tubular copper plating (38) and an annular copper layer, and the annular copper layer extends radially outward at both ends of the tubular copper plating (38); the tubular copper plating (38) runs through the central resin substrate.

2. The thick copper FCBGA package substrate according to claim 1, characterized in that: The resin substrate contains glass fibers.

3. The thick copper FCBGA package substrate according to claim 1, characterized in that: The copper thickness of the copper layer ranges from 25um to 50um.

4. The thick copper FCBGA package substrate according to claim 1, characterized in that: The hollow part of the tubular copper plating (38) is filled with a sealing glue (5), and the sealing glue (5) connects the two adjacent side resin substrates on both sides of the central resin substrate.

5. The thick copper FCBGA package substrate according to claim 1, characterized in that: The copper layer has a rough surface (39) on a side facing away from the central resin substrate, and the rough surface (39) is butted against the resin substrate in a concave-convex manner.

6. The thick copper FCBGA package substrate according to claim 1, characterized in that: The total number of layers of the resin substrate and the copper layer ranges from four to thirty layers.

7. The thick copper FCBGA package substrate according to claim 1, characterized in that: The copper layers are arranged in a mirror-symmetrical manner on both sides of the central resin substrate in a thickness direction.

8. The thick copper FCBGA package substrate according to claim 1, characterized in that: The resin substrate is a flame retardant material with a grade code of FR-4.

9. The thick copper FCBGA package substrate according to claim 1, characterized in that: The two side resin substrates which are farthest apart are respectively covered with a solder resist ink layer (2) on their opposite back surfaces.

10. The thick copper FCBGA package substrate according to claim 9, characterized in that: The solder resist ink layer (2) is penetrated by a prefabricated solder bump (1), and the prefabricated solder bump (1) is in contact with and connected to the copper layer.

11. A method for preparing a thick copper FCBGA package substrate, used to manufacture the thick copper FCBGA package substrate according to any one of claims 1 to 10, characterized in that: include: Intermediate steps, the intermediate steps comprising: Step S7: roughening the surface of the copper layer by using chemical solution to roughen the surface of the copper layer to form a rough surface; Step S8: Laminating a resin substrate made of bismaleimide triazine resin or epoxy resin with a thermal expansion coefficient between 0.1 PPM / °C and 20 PPM / °C and a copper foil on the roughened surface; Step S10: drilling holes on the surface of the resin substrate; Step S11: performing a desmear treatment on the surface of the resin substrate; Step S12: thinning the copper foil; Step S13: forming a seed copper layer in the holes formed by the punching; Step S14: applying a resist coating and exposing the pattern to light; Step S15: Development; Step S16: adjusting electroplating parameters to perform pattern electroplating to form a target copper thickness + α copper thickness; Step S17: stripping off the anti-plating film; Step S18: flash etching to form a build-up layer pattern; Step S19: Repeat the steps S7 to S18 until the designed number of added layers is obtained.

12. The method for preparing a thick copper FCBGA package substrate according to claim 11, characterized in that: The thickness of the copper foil in step S8 is in the range of 2um to 5um; The thickness of the copper foil after thinning in step S12 ranges from 0.3um to 2um; The α copper thickness in step S16 ranges from 1 um to 2 um.

13. The method for preparing a thick copper FCBGA package substrate according to claim 11, characterized in that: The punching in step S10 is laser punching; The desmear treatment in step S11 is a dry and / or wet desmear treatment; There is also a step S9 between step S8 and step S10, in which pre-drilling processing is performed. Step S9 includes selecting a laser source, controlling laser parameters, and adjusting a laser focus point.

14. The method for preparing a thick copper FCBGA package substrate according to claim 11, characterized in that: The intermediate step also includes a preparatory step before the intermediate step, and the preparatory step includes: Step S1: preparing a copper-clad laminate made of bismaleimide triazine resin or epoxy resin with a thermal expansion coefficient between 0.1 PPM / °C and 20 PPM / °C and a thickness between 0.10 mm and 1.50 mm, and heat-treating the copper-clad laminate to remove stress and moisture; Step S2: forming interconnection holes penetrating the copper clad laminate by laser drilling and / or mechanical drilling; Step S3: the interconnection holes are metallized by chemical copper plating or electrolytic copper plating, and the interconnection holes are plated holes after copper plating; Step S4: plugging the plated holes with resin; Step S5: performing chemical copper plating and electrolytic copper plating again until a copper cap is formed on the plated hole; Step S6: forming a circuit pattern by applying a photosensitive film, exposing, developing, and etching.

15. The method for preparing a thick copper FCBGA package substrate according to claim 11, characterized in that: The intermediate step also includes a post-step, and the post-step includes: Step S20: performing surface roughening treatment on the outermost resin substrate and the copper surface; Step S21: applying dry film solder resist ink, or applying liquid solder resist ink by printing or spraying; Step S22: ink leveling and exposure; Step S23: Development; Step S24: performing light and heat curing treatment; Step S25: performing chemical nickel-gold plating, chemical nickel-palladium-gold plating or chemical tin plating on the surface; Step S26: dividing and dicing the thick copper FCBGA package substrate; Step S27: ball planting or printed solder paste reflow to form prefabricated solder bumps (1); Step S28: further cutting the thick copper FCBGA package substrate after segmentation into individual PCB board units; Step S29: Flattening the prefabricated solder bump (1).

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