CN102555398B - Buffer material for hot press and its application - Google Patents

Abstract

The invention discloses a buffer material for a hot press and a stacking structure of the hot press using the buffer material, wherein the buffer material is prepared by forming fluorine-containing resin with a melting point of more than 260 ℃ and an elastic coefficient of more than 1000 kilograms per square centimeter into a required shape. The stacking structure of the hot press for manufacturing the laminated plate sequentially comprises a heating plate, a bearing disc, a buffer layer and a steel plate from outside to inside, wherein the heating plate, the bearing disc, the buffer layer and the steel plate are arranged in pairs, and the material of the laminated plate to be hot-pressed is arranged between the two steel plates. The cushion material is made of fluorine-containing resin, has good cushion property, thermal conductivity, durability and anti-sticking property, and has a smooth surface and is easy to adsorb and transfer.

Description

Buffer material for hot press and its application

technical field

The invention relates to a buffer material for a hot press and a stacking structure of a hot press using the buffer material.

Background technique

The laminated board is a composite layer structure formed by hot pressing process, such as flexible printed circuit board, IC carrier board, multilayer wiring board, printed circuit board (such as copper foil clad laminated board), etc. Taking a printed circuit board (PCB) as an example, it is formed by bonding several layers of film, insulating layer, adhesive layer and metal layer by hot pressing. In the hot pressing process, the control of temperature and pressure is extremely important, which not only directly affects the bonding effect between the layers of the obtained laminate, but also further affects the physical and electrical properties of the obtained laminate.

Taking the production of copper foil clad laminates as an example, the laminates are usually manufactured by the following method: a reinforcing material (such as glass fabric) is impregnated in a resin, and the reinforcing material impregnated with the resin is cured to Semi-hardened state (i.e. B-stage (B-stage)) to obtain a prepreg; then a certain number of layers of prepreg are laminated, and a copper foil is laminated on at least one outer side of the laminated prepreg to provide a a laminate material; and performing a hot pressing operation (ie, C-stage) on the laminate material to obtain a copper foil clad laminate.

The hot pressing operation of the above C-stage is carried out by a hot press machine. Generally speaking, the stacked structure of the hot press machine includes heating plates, carrying plates, buffer layers and steel plates arranged in pairs from the outside to the inside. The laminate material is placed between two steel plates for hot pressing. Among them, the buffer layer is used to ensure that the pressure and heat energy from the heating plate can be evenly transmitted to the surface of the laminated board material, so as to obtain a finished laminated board with good precision.

Because kraft paper has the advantages of low cost and uniform heat transfer effect, it is often used as the material of the buffer layer, that is, the buffer material. However, under high temperature (such as 150°C) hot pressing conditions, the tensile strength of kraft paper is less than 20% of that at room temperature, and its modulus of elasticity is as low as 250 million Pounds per square inch or less. In addition, after repeated use of kraft paper for many times, it is easy to cause the thermal resistance of the buffer material to increase and the heat transfer efficiency to decrease due to its own deterioration. Therefore, the number of repeated uses is limited, which is neither in line with the concept of environmental protection nor in line with economic benefits. In addition, kraft paper also has the problem of easy staining in practical applications (such as easy to stick to resin and glue overflow of laminated boards).

As far as the material of the buffer layer is concerned, there are currently several reusable buffer materials available, such as the buffer felt disclosed in U.S. Patent No. 4,284,680, the Chinese Taiwan Patent No. I231265 and No. I318924, which are composed of two components. Cushioning non-woven fabrics, etc. Although these cushioning materials have suitable cushioning effect, thermal conductivity and durability, they also have the problem of being easily stained, and the staining may even be aggravated due to the surface structure characteristics, which requires a lot of cleaning costs. Furthermore, these buffer materials have non-smooth and flat surfaces, which are not conducive to adsorption and transfer.

In view of this, the present invention provides a reusable buffer material for a hot press, which can be used as a buffer layer material in a stacked structure of a hot press. The cushioning material is made of fluorine-containing resin, which has good cushioning properties, thermal conductivity, durability and anti-sticking properties, and has a smooth surface for easy adsorption and transfer.

Contents of the invention

In order to solve the above problems, the object of the present invention is to provide a reusable buffer material for a hot press, which can be used as a buffer layer material in a stacked structure of a hot press.

Another object of the present invention is to provide a stacked structure of a heat press machine for manufacturing a laminate using the above buffer layer material.

The invention provides a buffer material for a hot press, which is obtained by forming a fluorine-containing resin with a melting point greater than 260°C and an elastic coefficient greater than 1000 kg/cm2 into a predetermined shape, which can be used as a hot press The buffer layer material in the stack structure of the machine.

The present invention also provides a stacking structure of a heat press machine for manufacturing laminated boards, which sequentially includes a heating plate arranged in pairs up and down, a carrying plate, a buffer layer including the above buffer material, and a steel plate from the outside to the inside , wherein the laminate material to be hot-pressed is placed between the two steel plates.

The beneficial effect of the present invention is that the cushioning material of the present invention has good cushioning properties, thermal conductivity, durability and anti-sticking properties, and is very suitable as a cushioning layer material in a stacked structure of a hot press. In addition, the buffer material made of fluorine-containing resin has a smooth surface, which is easy to absorb and transfer, and greatly improves the convenience of the process.

In order to make the above-mentioned purpose, technical features and advantages of the present invention more comprehensible, the following is a detailed description of some specific implementation forms.

Description of drawings

FIG. 1 is a schematic structural view of an embodiment of the stacked structure of the present invention.

Detailed ways

The following will specifically describe some specific implementation forms according to the present invention; just, without departing from the spirit of the present invention, the present invention can still be practiced in a variety of different forms, and the protection scope of the present invention should not be interpreted as being limited to the specification. declarant. In addition, "a", "the" and similar terms used in this specification (especially in the scope of the patent application) should be understood as including singular and plural forms, unless otherwise stated in the context. In addition, for the sake of clarity, the dimensions of various components and regions may be exaggerated in the drawings, but not drawn according to actual scale.

The buffer material of the present invention is made of a fluorine-containing resin. The buffer material has the characteristics of high heat resistance, high elastic coefficient, high thermal conductivity, anti-sticking property, flame resistance, high toughness, etc., and can be used alone to provide good It can also be used together with traditional kraft paper to greatly reduce the loss rate of kraft paper. In addition, compared with the existing cushioning materials of polymer felt and non-woven fabrics, the cushioning material of the present invention has excellent anti-adhesive properties, and has a smooth surface, so it is particularly beneficial for adsorption and transfer.

Specifically, the cushioning material of the present invention is produced by molding a fluorine-containing resin having a melting point greater than 260°C and an elastic modulus greater than 1000 kg/cm2 into a desired shape (predetermined shape). Due to its high melting point, the cushioning material of the present invention can avoid qualitative change during the hot pressing process, and because it is made of plastic and has a dense structure and a high elastic coefficient, it can provide the desired cushioning effect with a relatively thin thickness .

Without being limited by theory, any fluorine-containing resin with a melting point greater than 260° C. and an elastic modulus greater than 1000 kg/cm 2 can be used in the present invention. However, based on the convenience of raw material acquisition and price considerations, it is preferred to use fluorine-containing resins selected from the following groups: polydifluoroethylene, polytrifluoroethylene, polytetrafluoroethylene (polytetrafluoroethylene, PTFE), ethylene-tetrafluoroethylene Copolymer (poly(ethylene-co-tetrafluoroethylene), ETFE) and combinations thereof. In the appended examples, tetrafluoroethylene and ethylene-tetrafluoroethylene copolymers are used as examples.

The forming method of the cushioning material of the present invention is not particularly limited. Those skilled in the art may use appropriate forming methods according to their common knowledge, such as: molding-sintering method, extrusion Forming, impregnation molding, etc. In addition, the cushioning material of the present invention can be made into any shape and size according to user's needs. For example, it can be made into a sheet with a smooth surface to facilitate adsorption and transfer, or it can be made into a sheet with structures such as bumps or grooves on the surface to increase the cushioning capacity. Similarly, the thickness of the cushioning material of the present invention can also be designed according to the needs of users. Generally speaking, the cushioning material of the present invention with a thickness of about 0.05 mm to about 20 mm is suitable for most hot-pressing processes. In the attached examples, the smooth cushioning material sheets with a thickness of about 0.2 mm to about 0.25 mm were prepared by molding-sintering method or dip-press molding.

In order to improve the strength of the cushioning material, structural reinforcing materials can be introduced into the cushioning material of the present invention to prevent damage or slow down the expansion of the damage that has occurred during use. Reinforcing materials also provide proper stiffness to the cushioning material to avoid excessive stretching or twisting due to cyclic heat and pressure. For example, suitable reinforcing materials may be selected from the group consisting of glass fibres, natural fibres, organic fibres, woven or non-woven fabrics of one or more of the aforementioned fibers, and linter tissue paper. In some of the attached examples, it is exemplified that glass fiber cloth is used as a reinforcing material, and the reinforcing material is impregnated in a fluorine-containing resin glue solution, taken out and dried, and then subjected to a compression molding step to obtain the cushioning material of the present invention. material. In addition, in order to prevent edge damage, appropriate edge treatment can be carried out on the buffer material, such as the edge of the highly heat-pressed buffer material or the edge treatment of the buffer material to strengthen its edge structure.

It should be noted that, in addition to designing the thickness of the cushioning material according to the user's needs, the user's needs can also be met by adjusting the number of layers of the cushioning material used. In other words, by using multiple layers of thinner buffer materials instead of a single layer of thicker buffer materials, a similar buffer effect can be achieved without changing the specifications of the buffer materials, and the flexibility and applicability of the buffer materials can be improved. In the case of using a multi-layer cushioning material, the cushioning materials of each layer may have the same or different specifications (such as shape, thickness, etc.), for example, a cushioning material sheet with a smooth surface and a cushioning material with particle protrusions on the surface may be combined. The slices are used in combination. Of course, the cushioning material of the present invention can also be used together with existing cushioning materials. For example, in some of the attached embodiments, the cushioning material of the present invention is combined with kraft paper to form a desired cushioning layer. There are no special restrictions on the way of combined use, and adjustments can be made depending on the needs of users. For example, taking low-cost kraft paper as an example, considering that kraft paper is prone to sticking, it is better to coat both sides of the kraft paper with the cushioning material of the present invention.

According to the present invention, fillers can be added to the buffer material to enhance the properties of the buffer material, and the fillers can be selected from the following group: metals, inorganic oxides, carbonaceous materials, and combinations thereof. Specifically, one or more metals such as aluminum, silver, copper, nickel, etc. can be added to the buffer material to increase the thermal conductivity of the buffer material; one or more metals such as aluminum oxide, aluminum hydroxide, zinc oxide, di Inorganic oxides such as silicon oxide, boron nitride, kaolin, talc, mica, etc., to increase the thermal conductivity and pressure resistance of the buffer material; or add one or more carbonaceous materials such as activated carbon, graphite, carbon, etc., to increase the buffer The antistatic ability and stain resistance of the material. Although there is no special limitation on the amount of the filler, on the premise of not affecting the properties of the fluororesin itself and providing an effective gain effect, based on the weight of the fluororesin, the amount of the filler is preferably about 0.01% by weight to about 40% by weight, more preferably about 0.1% by weight to about 20% by weight, even more preferably about 1% by weight to about 15% by weight. If the filler is added in an amount lower than 0.01% by weight, the gain effect provided is not obvious; on the contrary, if the filler is added in an amount higher than 40% by weight, there may be problems affecting the properties of the fluorine-containing resin, and it will increase the process efficiency. Difficulty (e.g., the resin may be too thick to stir, or the degree of polymerization may be uneven, etc.). In addition, without being limited by theory, the shape of the filler is not particularly limited. Taking carbonaceous material as an example, it can be in the shape of powder, flake, nanotube, etc. As for the way of adding fillers, those skilled in the art can choose an appropriate technical solution according to their general knowledge after viewing this specification. For example, in the attached examples, before the fluorine-containing resin is cured and formed, the filler is firstly added to the fluorine-containing resin glue solution and mixed evenly, and then the resulting mixture is cured and formed into a cushioning material.

The present invention also provides a stacked structure of a heat press machine for manufacturing laminates, as shown in Figure 1, which sequentially includes a heating plate arranged in pairs up and down, a carrier plate, and a cushioning material of the present invention from the outside to the inside. The buffer layer and the steel plate, and the laminate material to be hot-pressed is placed between the two steel plates. Among them, as mentioned above, the cushioning material of the present invention can be used together with low-cost kraft paper to provide a desired cushioning layer, and the amount of kraft paper and the ratio of the cushioning material of the present invention can be freely matched according to user needs.

It should be noted that, in addition to the above configuration methods, depending on the application field, the buffer material of the present invention can be configured in various appropriate ways depending on the type of hot press machine used (such as directly contacting the material to be processed or not Direct contact with the material to be processed) into different stacking structures, so that the pressure and heat can be evenly distributed on the surface of the laminate material, providing the desired buffer effect, and obtaining a finished laminate with good precision. However, considering this configuration change is not the technical focus of the present invention, and those with ordinary knowledge in the art can choose an appropriate configuration according to their general knowledge after viewing the contents of this specification, so no detailed description will be given here. . For other configuration methods, please refer to the applicant's Taiwan Patent Application No. 099125584, the full text of which is hereby incorporated by reference.

The present invention is further exemplified with the following specific implementation forms, wherein the measuring instruments and methods used are as follows:

[melting point]

The melting point of the fluorine-containing resin was measured by the capillary melting point analyzer of Shangtai Company.

[Thermal conductivity]

The thermal conductivity of the buffer material was measured with a thermal conductivity analyzer from Hot Disk Company.

[elastic coefficient]

The elastic coefficient of the cushioning material is measured according to the tension and elasticity testing machine of Sanguang Instrument Company.

[flame resistance]

The flame resistance of the cushioning material was measured according to the UL-94 standard method.

[extensibility]

The ductility of the cushioning material was measured according to the standard method of the tensile and elastic testing machine of Sanko Instrument Company.

[sticky surface]

Visually observe the sticking condition of the cushioning material after using the heat press machine with the stacked structure of the present invention to carry out the heat pressing operation.

Example 1

Inject DuPont's ETFE glue (glue temperature at 280°C to 300°C) into the preheated mold (mold preheating temperature is 100°C to 150°C), and keep the glue in the mold for 1 to 2 minutes Thereafter, the mold was removed and the resulting shaped product was cooled to room temperature to obtain a smooth sheet of ETFE having a thickness of about 0.2 mm (cushion material 1). The relevant properties of the cushioning material 1 were measured by the aforementioned measurement methods, and the results are recorded in Table 1.

Use the single-layer buffer material 1 as the upper and lower buffer layers of the stacked structure of the hot press machine shown in Figure 1, and perform the hot pressing operation according to the following conditions to make a copper foil-coated laminate:

Laminate material: Four laminated prepregs, and one 1 oz copper foil laminated on each of the outermost layers on both sides, where the prepreg is 7628 fiberglass coated with epoxy resin Cloth (resin/glass fiber cloth: 43%); and

Hot pressing conditions: heat up to 180°C at a heating rate of 2.0°C/min, and press at 180°C with a total pressure of 15 kg/cm2 (initial pressure of 8 kg/cm2) for 60 minutes.

Observe the sticking condition of the buffer material 1 after the hot pressing operation, and record the results in Table 1.

Example 2

Inject DuPont's PTFE glue (glue temperature at 330°C to 350°C) into the preheated mold (mold preheating temperature is 100°C to 150°C), and keep the glue in the mold for 1 to 2 minutes Thereafter, the mold was removed and the resulting shaped product was cooled to room temperature to obtain a smooth sheet of PTFE having a thickness of about 0.2 mm (cushion material 2). The relevant properties of the cushioning material 2 were measured by the aforementioned measurement methods, and the results are recorded in Table 1.

The hot pressing operation was performed in substantially the same manner as in Example 1, but using the single-layer buffer material 2 as the upper and lower buffer layers, respectively. Observe the sticking condition of the buffer material 2 after the hot pressing operation, and record the results in Table 1.

Example 3

Soak the glass fiber cloth of Taiwan Glass Company (model: 7628, thickness: 170 microns) in the PTFE glue solution as in Example 2, take out the glass fiber cloth and press mold it (molding temperature: 150°C to 200°C) The glass fiber cloth was processed in the same manner to obtain a smooth sheet (cushion material 3) of glass fiber-containing PTFE with a thickness of about 0.24 mm. The relevant properties of the cushioning material 3 were measured by the aforementioned measurement methods, and the results are recorded in Table 1.

The hot-pressing operation was performed in substantially the same manner as in Example 1, but the single-layer buffer material 3 was used as the upper and lower buffer layers respectively. The adhesion of the buffer material 3 after the hot-pressing operation was observed, and the results were recorded in Table 1.

Example 4

The PTFE glue of DuPont (the temperature of glue keeps 330 ℃ to 350 ℃) and the active carbon powder of Shikoku Chemical Co., Ltd. are uniformly mixed in a ratio of 10:1 to obtain a glue mixture, and the resulting glue The mixture is poured into a preheated mold (the mold preheating temperature is 100°C to 150°C), and after the glue mixture is maintained in the mold for 1 minute to 2 minutes, the mold is removed and the resulting shaped product is cooled to room temperature to obtain A smooth sheet of activated carbon-containing PTFE (bumper 4) with a thickness of about 0.21 mm. The relevant properties of the cushioning material 4 were measured by the aforementioned measurement methods, and the results are recorded in Table 1.

The hot-pressing operation was performed in substantially the same manner as in Example 1, but the single-layer cushioning material 4 was used as the upper and lower buffer layers respectively. The adhesion of the cushioning material 4 after the hot-pressing operation was observed, and the results were recorded in Table 1.

Example 5

Make the buffer material of the present invention in the same manner as in Example 4, but replace the activated carbon powder with talcum powder to obtain a smooth sheet of PTFE containing talc powder with a thickness of about 0.22 mm (cushion material 5). The relevant properties of the cushioning material 5 were measured by the aforementioned measurement methods, and the results are recorded in Table 1.

The hot-pressing operation was performed in substantially the same manner as in Example 1, but the single-layer buffer material 5 was used as the upper and lower buffer layers respectively, and the adhesion of the buffer material 5 after the hot-pressing operation was observed, and the results were recorded in Table 1.

Example 6

The PTFE glue of DuPont (the temperature of the glue is maintained at 330°C to 350°C) and the activated carbon powder of Shikoku Chemical Co., Ltd. are evenly mixed in a ratio of 10:1 by weight to obtain a glue mixture, and then the PTFE glue of Taiwan Glass Co., Ltd. Glass fiber cloth (model: 7628, thickness: 170 microns) is impregnated in the obtained glue mixture, and the glass fiber cloth is taken out and processed by compression molding (compression molding temperature: 150°C to 200°C) , a smooth sheet (cushion material 6) of glass fiber-containing PTFE with a thickness of about 0.24 mm was obtained. The relevant properties of the cushioning material 6 were measured by the aforementioned measurement methods, and the results are recorded in Table 1.

The hot-pressing operation was performed in substantially the same manner as in Example 1, but the single-layer buffer material 6 was used as the upper and lower buffer layers. The adhesion of the buffer material 6 after the hot-pressing operation was observed, and the results are recorded in Table 1.

Comparative Example 7

Kraft paper sold by International Paper was used as a comparative cushioning material 7. The flame resistance of the comparative buffer material 7 was measured by the aforementioned measurement method, and the results are recorded in Table 1.

The hot-pressing operation was performed in substantially the same manner as in Example 1, but the single-layer comparative buffer material 7 was used as the upper and lower buffer layers respectively, and the adhesion of the comparative buffer material 7 after the hot-pressing operation was observed. The results are recorded in Table 1.

Table 1

It can be seen from Table 1 that the cushioning material of the present invention has a melting point greater than 260° C. and an elastic coefficient greater than 1000 kg/cm2, and its heat transfer coefficient is greater than 0.2 W/m.K and has excellent flame resistance. It is advantageous in terms of cushioning performance. In the surface adhesion test, the cushioning material of the present invention will not stick to the glue overflow of the laminate. In contrast, the traditional kraft paper (comparative cushioning material 7) has poor flame resistance and is prone to sticking situation. In addition, in the buffer material of the present invention, the service life of the buffer material can be increased through the use of reinforcing materials (such as the buffer material 3 and the buffer material 6); carbonaceous materials (such as the buffer material 4), inorganic Oxide (such as buffer material 5) and other fillers are used to increase the pressure resistance and antistatic properties of the buffer material. The use of the aforesaid reinforcing material or additional material can simultaneously reduce the consumption of relatively expensive fluorine-containing resin and reduce the production cost.

Embodiment 8: durability test

The stacking structure and hot-pressing conditions of the hot-press machine as in Example 1 were adopted, and the buffer layer shown in Table 2 was used to carry out the hot-pressing operation. After repeating the hot pressing operation 200 times, the durability of the buffer layer was visually observed, and the results are recorded in Table 2.

Table 2

It can be seen from Table 2 that whether the cushioning material of the present invention is used alone or in combination with kraft paper, it can provide good durability, greatly reduce the loss rate of the cushioning material, and reduce the production cost.

From the above results, it can be seen that the cushioning material of the present invention has good cushioning properties, thermal conductivity, durability and anti-sticking properties, and is very suitable as a cushioning layer material in a stacked structure of a hot press. In addition, the buffer material made of fluorine-containing resin has a smooth surface, which is easy to absorb and transfer, and greatly improves the convenience of the process.

The above-mentioned embodiments are only illustrative to illustrate the principles and effects of the present invention, and explain the technical features of the present invention, but are not intended to limit the scope of protection of the present invention. Any change or arrangement that can be easily accomplished by those skilled in the art without violating the technical principle and spirit of the present invention falls within the scope of the present invention. Therefore, the protection scope of the present invention is as listed in the appended patent scope.

Claims (9)

1. A buffer material for a hot press, characterized in that the whole is substantially made of a fluorine-containing resin formed into a sheet, and the melting point of the fluorine-containing resin is greater than 260° C. and the modulus of elasticity is greater than 1000 kg /cm2, and the fluorine-containing resin is selected from the following group: polydifluoroethylene, polytrifluoroethylene, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and combinations thereof. 2 . The buffer material according to claim 1 , wherein the fluorine-containing resin further comprises a filler, and based on the weight of the fluorine-containing resin, the content of the filler is 0.01 wt % to 40 wt %. 3. The buffer material according to claim 2, wherein the filler is selected from the group consisting of metals, inorganic oxides, carbonaceous materials and combinations thereof. 4. The buffer material according to claim 3, wherein the metal is a powder selected from the group consisting of aluminum, silver, copper, nickel and combinations thereof. 5. The buffer material according to claim 3, characterized in that the inorganic oxide is a powder selected from the group consisting of aluminum oxide, aluminum hydroxide, zinc oxide, silicon dioxide, boron nitride, kaolin, talc, mica and combinations of the foregoing. 6. The buffer material according to claim 3, wherein the carbonaceous material is selected from the group consisting of activated carbon, graphite and combinations thereof. 7. The cushioning material according to claim 1, wherein the thickness of the cushioning material is 0.05 mm to 20 mm. 8. A stacked structure for a heat press machine for manufacturing laminates, characterized in that it includes, from outside to inside, a heating plate arranged in pairs up and down, a carrying tray, and a heating plate according to any one of claims 1 to 7. A buffer layer of a buffer material and a steel plate, wherein the laminate material to be hot-pressed is placed between the two steel plates. 9. The stacked structure according to claim 8, wherein the buffer layer further comprises kraft paper.