CN115361795A - Semi-additive process method for FCBGA substrate - Google Patents

Abstract

The invention provides a semi-additive process method of an FCBGA substrate, and relates to the technical field of manufacturing of packaging substrates. The method comprises the following steps: step S1, sequentially laminating an ABF layer and a copper foil on the surface of an inner layer circuit of a packaging substrate; s2, placing the laminated ABF layer in an oven for baking to finish pre-curing; s3, carrying out vacuum heating and pressurization on the pre-cured ABF layer to completely cure the ABF layer; s4, removing the copper foil, and manufacturing an outer layer circuit on the completely cured ABF layer; and S5, repeating the steps S1 to S4 to form the multilayer circuit packaging substrate. The invention can solve the technical problem of large copper sheet explosion, ensure the reliability of the substrate, reduce the process limitation, improve the design freedom, reduce the process window, improve the yield and reduce the substrate warpage.

Description

Semi-additive process method for FCBGA substrate

technical field

The invention relates to the technical field of packaging substrate manufacturing, in particular to a semi-additive process method for FCBGA substrates.

Background technique

Due to the requirement of high-density wiring, the main process method of FCBGA (Flip Chip Ball Grid Array, flip-chip ball grid array) substrate manufacturing is the semi-additive method. The semi-additive method is not only a problem of copper circuit manufacturing technology, but this technology can usually only use ABF (Ajinomoto Build-up Film, Ajinomoto build-up film) material as the insulating layer. In other words, only ABF materials can realize high-density wiring by semi-additive method.

Due to the nature of the material itself, the ABF material contains a certain amount of solvent. If the solvent is not removed during the substrate manufacturing process, after the subsequent wiring layers accumulate multiple layers, the solvent accumulated in the substrate will easily cause the substrate to bubble and explode. . Continuous large-area copper skin cannot be set in the wiring metal layer of the substrate, and air holes at a certain distance must be processed in the area where the copper skin is required, so that the gas in the ABF layer can pass through to avoid explosion.

Contents of the invention

In view of the above problems, the present invention provides a semi-additive process method for FCBGA substrates, which avoids board explosion caused by large copper skins.

In order to achieve the above object, the present invention provides a semi-additive process method for FCBGA substrates, comprising: Step S1, sequentially pressing ABF layer 3 and copper foil 4 on the surface of the inner circuit 2 of the package substrate; Step S2, The pressed ABF layer 3 is baked in an oven to complete pre-curing; step S3, vacuum-heating and pressing the pre-cured ABF layer 3, so that the ABF layer 3 is completely cured; step S4, removing the copper foil 4 , manufacturing the outer circuit 9 on the fully cured ABF layer 3; step S5, repeating the above steps S1-S4 to form a multilayer circuit packaging substrate.

Further, in step S1 , before sequentially laminating the ABF layer 3 and the copper foil 4 , it also includes: roughening the surface of the inner circuit 2 .

Further, in step S2, the laminated ABF layer 3 is baked in an oven, including: firstly baking at 130° C. for 30 minutes, and then baking at 180° C. for 60 minutes.

Further, in step S3, the pre-cured ABF layer 3 is vacuum heated and pressurized, including: placing the pre-cured ABF layer 3 under vacuum conditions, under the clamping of the mirror isolation steel plate of the laminator, by heating And pressurize, the ABF layer 3 is completely cured.

Further, the temperature after heating is 190° C. to 210° C., and the pressure after pressurization is greater than 1 MPa.

Further, in step S4, the copper foil 4 is removed, and the outer layer circuit 9 is manufactured on the fully cured ABF layer 3, including: step S41, the fully cured ABF layer 3 and the copper foil 4 are laser drilled to make the ABF layer 3 and copper foil 4 to form a blind hole 5 communicating with the inner layer circuit 2; step S42, remove the residual slag from laser drilling; step S43, remove the surface copper foil 4; step S44, in the ABF layer 3 and the blind hole 5 Electroless copper plating to form an electroplating seed layer 6; step S45, forming a patterned electroplating mask 7 by photolithography on the electroplating seed layer 6; step S46, forming a circuit by electroplating in an area of the electroplating seed layer 6 that is not covered by the patterned electroplating mask 7 pattern 8 and fill the blind hole 5; step S47, remove the pattern electroplating mask 7; step S48, remove the electroplating seed layer 6 covered by the pattern electroplating mask 7, and form the outer circuit 9.

Further, in step S44, the thickness of the electroplating seed layer 6 is 0.3 μm˜1 μm.

Further, in step S5, after forming the multilayer circuit packaging substrate, it further includes: forming a solder resist layer 10 on the outermost layer of the multilayer circuit packaging substrate.

Further, after making the solder resist layer 10 , it also includes: coating an organic protective film 11 on the outermost area of the multilayer circuit packaging substrate not covered by the solder resist layer 10 .

Further, the material of the organic protective film 11 includes any one of NiAu, NiPdAu, OSP, and Sn.

Compared with the prior art, the semi-additive process method of the FCBGA substrate provided by the present invention has at least the following beneficial effects:

(1) The large copper skin does not explode, ensuring the reliability of the substrate;

(2) Reduce process restrictions and increase design freedom;

(3) Reduce the process window and improve the yield rate;

(4) Reduce substrate warpage.

Description of drawings

Through the following description of the embodiments of the present invention with reference to the accompanying drawings, the above-mentioned and other objects, features and advantages of the present invention will be more clear, in the accompanying drawings:

Fig. 1 schematically shows the operation flowchart of the semi-additive process method of the FCBGA substrate according to the embodiment of the present invention;

Fig. 2 schematically shows the process flow chart of the semi-additive process method of the FCBGA substrate according to the embodiment of the present invention;

Fig. 3 schematically shows the operation flowchart of the manufacturing process of the outer layer circuit according to the embodiment of the present invention;

FIG. 4 schematically shows a process flow diagram of the manufacturing process of the outer layer circuit according to an embodiment of the present invention;

FIG. 5 schematically shows a structural diagram of a multilayer circuit packaging substrate according to an embodiment of the present invention;

FIG. 6 schematically shows a structural diagram of a solder resist layer according to an embodiment of the present invention;

Fig. 7 schematically shows a structure diagram of an organic protective film according to an embodiment of the present invention.

[Description of Reference Signs]

1-core board; 2-inner layer circuit; 3-ABF layer; 4-copper foil; 5-blind hole; 6-electroplating seed layer; 7-graphic plating mask; 8-circuit pattern; 9-outer layer circuit; 10-solder resist layer; 11-organic protective film.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings. Apparently, the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting of the invention. The terms "comprising", "comprising", etc. used herein indicate the presence of stated features, steps, operations and/or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

All terms (including technical and scientific terms) used herein have the meaning commonly understood by one of ordinary skill in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted to have a meaning consistent with the context of this specification, and not be interpreted in an idealized or overly rigid manner.

FIG. 1 schematically shows an operation flowchart of a semi-additive process method for an FCBGA substrate according to an embodiment of the present invention. FIG. 2 schematically shows a process flow diagram of a semi-additive process method for an FCBGA substrate according to an embodiment of the present invention.

Please refer to FIG. 1 and FIG. 2 , the semi-additive process method for the FCBGA substrate according to this embodiment may include steps S1 to S5.

In step S1, the ABF layer 3 and the copper foil 4 are laminated sequentially on the surface of the inner circuit 2 of the packaging substrate.

The innermost layer material of the packaging substrate is a core board 1 , on which a copper circuit is manufactured as an inner layer circuit 2 . The manufacturing method and structure of the inner layer circuit 2 are the same as those of a conventional printed circuit board. For example, as shown in FIG. The inner circuit 2 is filled in the slot and extends to the upper and lower surfaces of the core board 1 .

Before sequentially laminating the ABF layer 3 and the copper foil 4 , it is necessary to roughen the surface of the inner circuit 2 to improve the bonding force between the inner circuit 2 and the ABF layer 3 .

The embodiment of the present invention adopts the ABF layered product as the circuit interlayer insulating material, which can be used to manufacture precise circuits on the surface of the material by using a semi-additive process.

Next, on the surface of the inner circuit 2 , the ABF layer 3 can be laminated first by using a vacuum film laminating machine at a temperature lower than the conventional one, and then the copper foil 4 can be laminated on the surface of the ABF layer 3 .

In step S2, the laminated ABF layer 3 is baked in an oven to complete pre-curing.

This step adopts low-temperature baking, the main purpose of which is to remove the water vapor absorbed by the packaging substrate during processing. Specifically, the laminated ABF layer 3 is baked in an oven, which may be baked at 130° C. for 30 minutes, and then baked at 180° C. for 60 minutes. After baking, the curing degree of ABF layer 3 increased slightly.

In step S3, the pre-cured ABF layer 3 is vacuum-heated and pressurized to completely cure the ABF layer 3 .

In the embodiment of the present invention, vacuum heating and pressurizing the pre-cured ABF layer 3 may include: placing the pre-cured ABF layer 3 under vacuum conditions, clamped by the mirror isolation steel plate of the laminator, by heating And pressurize, the ABF layer 3 is completely cured.

Further, the temperature after heating may be 190°C-210°C, and the pressure after pressurization may be greater than 1 MPa.

It should be noted that the conventional ABF curing is to bake in an oven at 130°C for 30 minutes after the ABF surface circuit is made, and then bake in an oven at a temperature of 190°C to 210°C for 1 hour. However, in the embodiment of the present invention, the pre-cured packaging substrate is clamped by the mirror isolation steel plate in the laminator, and the ABF is completely cured in a vacuum chamber under the action of temperature and pressure.

In step S4 , the copper foil 4 is removed, and the outer circuit 9 is manufactured on the fully cured ABF layer 3 .

In step S5, the above steps S1-S4 are repeated to form a multilayer circuit packaging substrate.

Thus, the outer circuit 9 is fabricated on the surface of the fully cured ABF layer 3, and the outer circuit 9 is used as the inner circuit 2 to repeat the above steps to obtain a multilayer circuit packaging substrate.

In order to specifically illustrate the manufacturing process of the outer layer circuit 9, Fig. 3 schematically shows the operation flow chart of the manufacturing process of the outer layer circuit according to an embodiment of the present invention, and Fig. 4 schematically shows the outer layer according to an embodiment of the present invention Process flow chart of the manufacturing process of the circuit.

Please refer to Fig. 3 and Fig. 4, in the embodiment of the present invention, in the above step S4, the copper foil 4 is removed, and the outer layer circuit 9 is manufactured on the fully cured ABF layer 3, which may further include steps S41 to S48.

Step S41 , laser drilling is performed on the fully cured ABF layer 3 and copper foil 4 , so that blind holes 5 communicating with inner-layer circuits 2 are formed in the ABF layer 3 and copper foil 4 .

Laser drilling forms blind holes 5 in the ABF layer 3 and copper foil 4 that communicate with the inner layer lines 2, thereby forming interlayer interconnection channels.

It should be noted that the conventional laser drilling process is completed on the surface of the pre-cured ABF. Different from the conventional process, the laser drilling process in the embodiment of the present invention is completed on the surface of the fully cured ABF layer 3 .

Step S42, removing residual glue residue from laser drilling.

Residual slag carried by the laser drilling inside the blind hole 5 is removed. Different from the conventional process, the conventional process is to remove the glue on the surface of the pre-cured ABF hole.

Step S43 , removing the surface copper foil 4 .

Thus, the ABF layer 3 and the blind holes 5 are exposed.

Step S44 , electroless copper plating in the ABF layer 3 and the blind hole 5 to form an electroplating seed layer 6 .

Electroless copper plating provides conductivity for subsequent electroplating. Different from conventional electroless copper plating deposited on the surface of the pre-cured ABF, the electroless copper plating of the embodiment of the present invention is deposited on the surface of the fully cured ABF layer 3, and the non-hole area of the ABF layer 3 is not subjected to glue removal and roughening treatment. .

Further, the thickness of the electroplating seed layer 6 may be 0.3 μm˜1 μm.

Step S45 , forming a patterned electroplating mask 7 on the electroplating seed layer 6 by photolithography.

A dry film is pressed on the electroplating seed layer 6, and a pattern electroplating mask 7 is formed by photolithography and development.

Step S46 , forming circuit pattern 8 by electroplating in the area of electroplating seed layer 6 not covered by pattern electroplating mask 7 and filling blind hole 5 .

This step is pattern electroplating, which is used to plate out the circuit pattern 8 .

Step S47, removing the patterned plating mask 7.

Step S48 , removing the electroplating seed layer 6 covered by the pattern electroplating mask 7 to form the outer circuit 9 .

The electroplating seed layer covered by the pattern electroplating mask 7 is removed by rapid etching to form the outer circuit 9 .

Next, FIG. 5 schematically shows a structure diagram of a multilayer circuit packaging substrate according to an embodiment of the present invention.

As shown in Figure 5, in the embodiment of the present invention, the manufactured outer layer circuit 9 is used as the inner layer circuit 2, and the above steps S1-S4 are repeated, so that the inner layer circuit 2, the ABF layer 3 and the outer layer circuit 9 are alternately stacked , to obtain a multilayer circuit packaging substrate.

FIG. 6 schematically shows a structure diagram of a solder resist layer according to an embodiment of the present invention.

As shown in FIG. 6 , in the embodiment of the present invention, in step S5 , after forming the multilayer circuit packaging substrate, it may further include: making a solder resist layer 10 on the outermost layer of the multilayer circuit packaging substrate. As a protective layer, the solder resist layer can be coated on the circuit or base material of the package substrate that does not need to be soldered, and can also protect the formed circuit pattern for a long time.

Fig. 7 schematically shows a structure diagram of an organic protective film according to an embodiment of the present invention.

As shown in FIG. 7 , in the embodiment of the present invention, after making the solder resist layer 10 , it may further include: coating an organic protective film 11 on the outermost area of the multilayer circuit packaging substrate not covered by the solder resist layer 10 . The coating of the organic protective film can not only protect the copper from oxidation, but also improve the solderability of the copper pad.

Further, the material of the organic protective film 11 includes any one of NiAu, NiPdAu, OSP, and Sn.

From the above description, it can be seen that the semi-additive process method of the FCBGA substrate provided by the embodiment of the present invention at least achieves the following technical effects:

(1) The large copper skin does not explode, ensuring the reliability of the substrate;

(2) Reduce process restrictions and increase design freedom;

(3) Reduce the process window and improve the yield rate;

(4) Reduce substrate warpage.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Therefore, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined. Furthermore, the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A semi-additive process method of an FCBGA substrate is characterized by comprising the following steps:

the method comprises the following steps of S1, sequentially pressing an ABF layer (3) and a copper foil (4) on the surface of an inner layer circuit (2) of a packaging substrate;

s2, placing the laminated ABF layer (3) in an oven for baking to finish pre-curing;

s3, carrying out vacuum heating and pressurization on the pre-cured ABF layer (3) to completely cure the ABF layer (3);

s4, removing the copper foil (4), and manufacturing an outer layer circuit (9) on the completely solidified ABF layer (3);

and S5, repeating the steps S1 to S4 to form the multilayer circuit packaging substrate.

2. The FCBGA substrate semi-additive process method of claim 1, wherein the step S1 further comprises, before the step of sequentially laminating the ABF layer (3) and the copper foil (4):

and roughening the surface of the inner layer circuit (2).

3. The semi-additive process method for FCBGA substrate of claim 1, wherein in step S2, the step of baking the laminated ABF layer (3) in an oven comprises:

baking at 130 deg.C for 30min, and baking at 180 deg.C for 60min.

4. The semi-additive process of FCBGA substrate of claim 1, wherein in step S3, said vacuum heating and pressurizing the pre-cured ABF layer (3) comprises:

and (2) putting the pre-cured ABF layer (3) under a vacuum condition, and heating and pressurizing under the clamping of a mirror surface isolation steel plate of a laminating machine to completely cure the ABF layer (3).

5. The semi-additive process of claim 4, wherein the temperature after heating is 190 ℃ to 210 ℃, and the pressure after pressurizing is greater than 1MPa.

6. The semi-additive process of FCBGA substrate of claim 1, wherein in step S4, said removing said copper foil (4) and fabricating outer layer traces (9) on the fully cured ABF layer (3) comprises:

step S41, carrying out laser drilling on the completely cured ABF layer (3) and the copper foil (4) to form a blind hole (5) communicated with the inner layer circuit (2) in the ABF layer (3) and the copper foil (4);

s42, removing residual glue residues of laser drilling;

step S43, removing the surface copper foil (4);

step S44, electroless copper plating is carried out in the ABF layer (3) and the blind holes (5) to form a plating seed layer (6);

step S45, forming a pattern electroplating mask (7) on the electroplating seed layer (6) through photoetching;

step S46, forming a circuit pattern (8) in the electroplating seed layer (6) in an electroplating area uncovered by the pattern electroplating mask (7) by electroplating and filling the blind hole (5);

s47, removing the pattern electroplating mask (7);

and S48, removing the electroplating seed layer (6) covered by the pattern electroplating mask (7) to form the outer layer circuit (9).

7. The FCBGA substrate semi-additive process method of claim 6, wherein in step S44, the plating seed layer (6) has a thickness of 0.3 μm to 1 μm.

8. The FCBGA substrate semi-additive process of claim 1, wherein the step S5, after forming the multi-layer circuit package substrate, further comprises:

and manufacturing a solder mask layer (10) on the outermost layer of the multilayer circuit packaging substrate.

9. The FCBGA substrate semi-additive process of claim 8, wherein after the solder mask layer (10) is formed, the method further comprises:

and an organic protective film (11) is coated on the region of the outermost layer of the multilayer circuit packaging substrate, which is not covered by the solder mask layer (10).

10. The FCBGA substrate semi-additive process of claim 9, wherein the organic protective film (11) material comprises any one of NiAu, niPdAu, OSP, sn.

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