CN119031584A - A single-sided flip chip film with high heat dissipation and chemical etching method thereof - Google Patents

Abstract

The invention discloses a high-heat-dissipation single-sided flip chip film and a chemical etching method thereof, and relates to the technical field of flip chip film preparation. According to the high-heat-dissipation single-sided flip chip film and the chemical etching method thereof, the PI layer is provided with the plurality of through holes, the through holes are avoided, the heat dissipation surface area of an Integrated Circuit (IC) is increased, the heat dissipation effect is improved, meanwhile, the arrangement of the Integrated Circuit (IC) is not affected, copper is electroplated in the through holes, the heat is guided to the radiating fins by utilizing the high heat conductivity of a copper material, the heat dissipation effect is further improved, the improved single-sided flip chip film has high heat dissipation, the heat generated in the working process can be effectively released, and the temperature rise caused by heat accumulation is prevented from affecting the working efficiency of the IC.

Description

A single-sided flip chip film with high heat dissipation and chemical etching method thereof

Technical Field

The invention relates to the technical field of chip-on-chip film preparation, in particular to a single-sided chip-on-chip film with high heat dissipation performance and a chemical etching method thereof.

Background Art

Chip-on-film, or COF for short, is a soft film assembly technology that fixes an integrated circuit (IC) on a flexible circuit board. It uses a soft additional circuit board as a package chip carrier to combine the chip with a soft substrate circuit, or refers to a soft additional circuit board for an unpackaged chip. Chip-on-film technology makes the product thinner and lighter, meeting the strict requirements of modern electronic products on size and weight, and the line spacing can be very fine, such as a pitch of 16μm, which increases the reliability and integration of the product. Compared with traditional TAB technology, COF does not have the problem of easy deformation or breakage of hanging leads, which helps to improve production yield and reduce manufacturing costs. Therefore, this technology is very suitable for small-size panels such as liquid crystal module products such as mobile phones or PDAs.

Single-sided Flip Chip refers to a method of mounting chips on one side (single-sided) of a flexible substrate. This method still has the main advantages of COF technology and is usually used in scenarios where double-sided chip layout is not required. However, due to the single-sided assembly, the density of integrated circuits in single-sided Flip Chip is higher than that of double-sided Flip Chip, so its requirements for heat dissipation are also higher.

However, the existing single-sided flip chip film generally assists the circuit components in dissipating heat by gluing a heat sink on the surface where the integrated circuit is located, but this still cannot meet the heat dissipation requirements of the single-sided flip chip film. The heat generated during operation is prone to accumulation, causing its temperature to rise, which is not conducive to maintaining the stable working state of the driver chip. It will also cause performance degradation or damage due to high temperature, shortening its service life.

Therefore, it is urgent to improve this shortcoming. The present invention studies and improves the existing structure and shortcomings, and provides a high heat dissipation single-sided flip chip film and a chemical etching method thereof.

Summary of the invention

The object of the present invention is to provide a single-sided flip chip film with high heat dissipation and a chemical etching method thereof to solve the problems raised in the above background technology.

To achieve the above object, the present invention provides the following technical solutions:

In the first aspect, a single-sided flip chip film with high heat dissipation is provided, wherein the single-sided circuit flip chip film is bonded to an IC. Since the IC operation generates heat energy and is not easy to dissipate heat, a via hole is opened at the bottom of the PI, and the via hole is filled with copper by electroplating. A heat sink is fixedly connected to the bottom of the PI layer.

In a second aspect, a chemical etching method for a high heat dissipation single-sided chip-on-chip film is provided, which is applied to the high heat dissipation single-sided chip-on-chip film as described above, and comprises the following steps:

S1. Raw material preparation: Select a suitable single-sided copper substrate as the starting material, check the material quality to ensure there are no defects, and perform necessary pretreatment;

S2, dry film lamination: accurately align the dry film and substrate, and use a laminating machine to press the dry film onto the substrate;

S3, via hole exposure: the via hole position on the dry film is exposed through a photomask to cause a chemical reaction of the photosensitive material in the exposed part;

S4, via hole development: using a developer to remove the dry film portion that is no longer needed after exposure, exposing the via hole position on the substrate;

S5. Etching the copper surface of the via hole: etching the copper surface using an etchant through a chemical etching device;

S6, Dry film stripping: Use stripping fluid or mechanical methods to remove the remaining dry film;

S7, chemically etching PI vias: chemically etching the polyimide (PI) layer by chemical etching equipment to form a final via structure;

S8, Black shadow: Use black shadow agent, which contains unique additives and conductive colloidal substances (graphite), attached to the wall of PI via hole to form a conductive layer function;

S9, dry film lamination: align the dry film and substrate, and use a laminating machine at a certain temperature and pressure to firmly adhere the dry film to the substrate;

S10, circuit exposure: exposing the dry film through a photomask to cause a chemical reaction in the photosensitive material of the exposed part;

S11, circuit development: using a developer to remove the dry film portion that is no longer needed after exposure, exposing the copper layer on the substrate, and forming a circuit pattern;

S12, Circuit copper plating: Use electroplating equipment to control the composition, temperature and current density of the electroplating solution, electroplate a layer of copper on the exposed copper layer, and also fill the via holes with copper plating;

S13, dry film stripping: Use stripping liquid or mechanical method to remove the remaining dry film to expose the complete circuit pattern;

S14: Remove the bottom copper of the raw material without layer increase to form the circuit;

S15, Tinning: Use a tin-containing acid solution on the copper surface with circuits, and use a special tinning equipment to chemically deposit a layer of tin on the copper surface. The purpose is to bind the IC and form a eutectic package with the IC's gold bumps;

S16, Solder mask printing: Use screen printing in the non-bonding area to print a layer of solder mask on the conductive area of the circuit to prevent the outer layer from oxidation or contact short circuit.

S17, attaching heat sink: Use heat pressing method to attach heat sink to the back of the substrate.

The present invention provides a single-sided chip-on-chip film with high heat dissipation and a chemical etching method thereof, which has the following beneficial effects:

The present invention opens a plurality of via holes on the PI layer, avoiding the integrated circuit (IC), and increases the heat dissipation surface area of the PI layer by using the via holes, thereby improving the heat dissipation effect without affecting the layout of the integrated circuit (IC). The via holes are filled with copper by electroplating, and the high thermal conductivity of the copper material is used to conduct the heat to the heat sink, thereby further improving the heat dissipation effect. The improved single-sided flip chip film has high heat dissipation, can effectively release the heat generated during the working process, and prevent the temperature increase caused by heat accumulation from affecting the working efficiency of the IC. It not only helps to maintain the stable working state of the driver chip, but also can avoid performance degradation or damage caused by high temperature, thereby extending its service life.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a front cross-sectional structure of a single-sided flip chip film with high heat dissipation performance according to the present invention.

FIG. 2 is a schematic diagram of an existing heat dissipation technology of a single-sided chip-on-film with high heat dissipation performance according to the present invention.

DETAILED DESCRIPTION

The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

As shown in Figures 1 and 2, a single-sided flip chip film with high heat dissipation performance is used. The single-sided circuit flip chip film is bonded to the IC. Since the IC operation generates heat energy and is not easy to dissipate heat, a via hole is opened at the bottom of the PI, and the via hole is electroplated with copper. A heat sink is fixedly connected to the bottom of the PI layer.

A chemical etching method for a high heat dissipation single-sided chip-on-chip film is applied to the high heat dissipation single-sided chip-on-chip film as described above, comprising the following steps:

S1. Raw material preparation: Select a suitable single-sided copper substrate as the starting material (the starting material is composed of a PI layer and a copper surface), check the material quality to ensure that there are no defects, and perform necessary pretreatment, using solvents, sandpaper or mechanical polishing to clean the substrate surface;

S2, dry film lamination: accurately align the dry film and substrate, and use a laminator to press the dry film (a film containing photosensitive substances) onto the substrate in preparation for subsequent pattern exposure;

S3, via hole exposure: the via hole position on the dry film is exposed through a photomask to cause a chemical reaction of the photosensitive material in the exposed part;

S4, via hole development: using a developer to remove the dry film portion that is no longer needed after exposure, exposing the via hole position on the substrate;

S5. Etching the copper surface of the via hole: etching the copper surface using an etchant through a chemical etching device;

S6, Dry film stripping: Use stripping fluid or mechanical methods to remove the remaining dry film;

S7, chemical etching of PI vias: chemically etching the polyimide (PI) layer by chemical etching equipment to process surface defects such as burrs on the PI layer to form the final via structure;

S8, Black shadow: Use black shadow agent, which contains unique additives and conductive colloidal substances (graphite), attached to the wall of PI via hole to form a conductive layer function;

S9, dry film lamination: align the dry film and substrate, and use a laminating machine at a certain temperature and pressure to firmly adhere the dry film to the substrate;

S10, circuit exposure: exposing the dry film through a photomask to cause a chemical reaction in the photosensitive material of the exposed part;

S11, circuit development: using a developer to remove the dry film portion that is no longer needed after exposure, exposing the copper layer on the substrate, and forming a circuit pattern;

S12, circuit copper plating: before copper electroplating, use chemical agents for activation treatment, and coat a conductive layer on the hole wall and the circuit. Use electroplating equipment to control the composition, temperature and current density of the electroplating solution, electroplate a layer of copper on the exposed copper layer, and also fill the conductive hole with copper plating; and after the electroplating is completed, take the substrate out of the electroplating tank and clean it to remove the electroplating solution residue and impurities on the surface, and perform deoxidation treatment to remove the oxides generated during the electroplating process;

S13, dry film stripping: Use stripping liquid or mechanical method to remove the remaining dry film to expose the complete circuit pattern;

S14: Remove the bottom copper of the raw material without layer increase to form the circuit;

S15, Tinning: Use a tin-containing acid solution on the copper surface with circuits, and use a special tinning equipment to chemically deposit a layer of tin on the copper surface. The purpose is to bind the IC and form a eutectic package with the IC's gold bumps;

S16. Use screen printing to print a layer of solder resist ink on the non-bonding area of the circuit conductive area to prevent the outer layer of the circuit from oxidation or contact short circuit. The solder resist ink is used to form a protective film on the circuit board, and needs to be dried and cured after printing to form a solid solder resist layer. The solder resist ink is divided into heat curing type, UV curing type and liquid photosensitive type according to the curing method;

S17, attaching heat sink: Use heat pressing method to attach heat sink to the back of the substrate.

The embodiments of the present invention are given for the purpose of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

Claims (6)

1. The utility model provides a high heat dissipation single face flip chip film, its characterized in that, single face circuit flip chip film binds IC, because IC operation can produce heat energy, is difficult for the heat dissipation, then has offered the via hole in PI's bottom to the copper is filled in the electroplating in the via hole, the bottom fixedly connected with fin on PI layer.

2. A chemical etching method of a high heat dissipation single-sided flip chip film, applied to the high heat dissipation single-sided flip chip film as claimed in claim 1, comprising the steps of:

s1, preparing raw materials: selecting a proper single-sided copper base material as a starting material, checking the quality of the material, ensuring no defect, and carrying out necessary pretreatment;

s2, dry film lamination: precisely aligning the dry film with the substrate, and pressing the dry film on the substrate by using a pressing machine;

S3, exposure of the through hole: exposing the via holes on the dry film through a photomask to enable the photosensitive substances in the exposed parts to have chemical reaction;

S4, developing through holes: removing the dry film part which is not needed after exposure by using a developing solution, and exposing the via hole position on the substrate;

s5, etching conduction Kong Tongmian: etching the copper surface by using an etchant through chemical etching equipment;

S6, stripping a dry film: removing the residual dry film by using a stripping solution or a mechanical method;

s7, chemically etching the PI via hole: and chemically etching the polyimide layer by chemical etching equipment to form a final via structure.

3. The method for chemically etching a high thermal dissipation single-sided flip chip film according to claim 2, further comprising the steps of:

S8, shadow: the black shadow agent is utilized, the components contain unique additives and conductive colloid substances, and a conductive layer function is formed by adhering to the wall of the PI conducting hole;

S9, dry film lamination: aligning the dry film with the substrate, and firmly attaching the dry film to the substrate at a certain temperature and pressure by using a pressing machine;

s10, line exposure: exposing the dry film through a photomask to enable the photosensitive substances in the exposed part to chemically react;

s11, line development: and removing the dry film part which is not needed after exposure by using a developing solution, exposing the copper layer on the substrate, and forming a circuit pattern.

4. The method for chemically etching a high thermal dissipation single-sided flip chip film according to claim 3, further comprising the steps of:

s12, copper plating of a circuit: electroplating a layer of copper on the exposed copper layer by using electroplating equipment, controlling the composition, the temperature and the current density of the electroplating solution, and simultaneously filling copper into the through holes;

s13, dry film stripping: removing the residual dry film by using a stripping solution or a mechanical method to expose the complete circuit pattern;

s14, removing the base copper, namely removing the base copper of the raw material without the build-up layer, and forming the circuit.

5. The method for chemically etching a high thermal dissipation single-sided flip chip film according to claim 4, further comprising the steps of:

s15, tin melting: the copper surface with the circuit is subjected to tin-containing acid solution, and a layer of tin is deposited on the copper surface by a chemical method through special tin melting equipment, so that the copper surface with the circuit is subjected to eutectic encapsulation with gold bumps of an Integrated Circuit (IC) for the purpose of IC binding;

S16, printing solder mask ink: screen printing is used to print a layer of solder resist ink on the non-bonding area of the circuit conductive area so as to prevent the outer layer line from oxidizing or contacting short circuit.

6. The method for chemically etching a high thermal dissipation single-sided flip chip film according to claim 5, further comprising the steps of:

s17, sticking a cooling fin: and attaching a heat sink to the back surface of the base material by using a hot pressing method.