KR102521064B1 - Polyolefin based low-k adhesive composition including LCP filler and low-k bonding sheet using the same - Google Patents

Abstract

Disclosed are a polyolefin-based low-dielectric adhesive composition, and a low-dielectric bonding sheet using the same, wherein the polyolefin-based low-dielectric adhesive composition contains 20 to 50 wt% of the total weight of the composition of an LCP filler with a particle distribution D50 of 5-15 ㎛. According to the polyolefin-based adhesive composition and the bonding sheet and a printed circuit board to which the polyolefin-based adhesive composition is applied, there are excellent low dielectric properties of low dielectric constant and low dielectric loss rates, and excellent adhesion required in the PCB or FPCB manufacturing process, as well as excellent soldering heat resistance, resin flow, thermal expansion coefficient, and rheological viscosity properties.

Description

Polyolefin based low-k adhesive composition including LCP filler and low-k bonding sheet using the same

The present specification discloses a polyolefin-based low-dielectric adhesive composition including an LCP filler and a low-dielectric bonding sheet using the same.

Recently, according to the light weight, miniaturization and high density of electronic products using printed circuit boards (PCBs), it is necessary to mount them easily in a narrower space. Flexible Printed Circuit Boards; FPCB) is being adopted as a core substrate for electronic products.

Since the flexible printed circuit board uses a laminated plate manufactured by attaching metal foil to the surface of a flexible insulating film as a base material, it is thin and easily bendable, enabling three-dimensional wiring, which is advantageous for miniaturization and light weight of devices. am.

Currently, demands for high integration, high refinement, and high performance in the PCB field are increasing, and high-capacity and high-speed transmission are becoming a major topic. there is.

Moreover, in order to transmit large amounts of information at high speed in 5G communication, a low dielectric constant and dielectric loss tangent are required. In particular, the dielectric loss tangent is directly related to the transmission loss, and the transmission loss increases rapidly as the frequency increases.

For example, in the past, silica fillers are commonly used as fillers in insulating layers, and low dielectric bonding sheets using them have a dielectric loss tangent of 0.0020.

In exemplary embodiments of the present invention, on one side, an LCP filler having excellent adhesion while having low permittivity and dielectric loss tangent, and also having excellent soldering heat resistance, resin flow, thermal expansion coefficient, rheological viscosity and physical properties It is to provide a polyolefin-based low-dielectric adhesive composition comprising the same and a low-dielectric bonding sheet using the same.

In exemplary embodiments of the present invention, as a polyolefin-based low-k dielectric adhesive composition, the polyolefin-based low-k dielectric adhesive composition includes an LCP filler having a particle distribution D50 of 5 to 15 μm or a filler including an LCP filler at 20 to 50 wt% of the total weight of the composition. An adhesive composition is provided.

In exemplary embodiments of the present invention, a bonding sheet in which a base film, a polyolefin-based adhesive layer made of the above-described polyolefin-based adhesive composition, and a release layer are laminated is provided.

In exemplary embodiments of the present invention, a polyolefin-based adhesive layer made of the above-described polyolefin-based adhesive composition is provided on a printed circuit board formed on an insulating layer surface or a circuit surface of the printed circuit board.

In exemplary embodiments of the present invention, also, coating the above-described polyolefin-based adhesive composition on a base film to form a polyolefin-based adhesive layer; and forming a release layer on the polyolefin-based adhesive layer.

In exemplary embodiments of the present invention, also, peeling off the base film or release layer of the bonding sheet and attaching the polyolefin adhesive layer to the insulating layer surface or circuit surface of the printed circuit board; manufacturing a printed circuit board comprising provides a way

According to the polyolefin-based adhesive composition of exemplary embodiments of the present invention, and the bonding sheet and printed circuit board to which the same is applied, the low dielectric constant and low dielectric loss ratio are excellent, while the adhesion required in the PCB or FPCB manufacturing process is excellent, In addition, it has excellent properties such as soldering heat resistance, resin flow, thermal expansion coefficient, and rheological viscosity.

1 is a schematic diagram showing a bonding sheet layer configuration of an exemplary embodiment of the present invention.

Hereinafter, exemplary implementations of the present invention will be described in more detail.

The embodiments of the present invention disclosed in the text are illustrated for purposes of explanation only, and the embodiments of the present invention may be implemented in various forms and should not be construed as being limited to the embodiments described in the text. . The present invention can have various changes and can have various forms, the embodiments are not intended to limit the present invention to a specific form disclosed, and all changes, equivalents or substitutes included in the spirit and technical scope of the present invention It will be understood to include.

Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "comprise" or "having" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features The possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not excluded.

In this specification, the LCP filler means a liquid crystal polymer filler.

In the present specification, adhesion refers to adhesive strength (kgf/cm) obtained by bonding between copper foil and an insulating film such as a polyimide film using a bonding sheet. The minimum specification of adhesion is 0.7 kgf/cm or more.

In this specification, soldering heat resistance means heat resistance at a temperature exceeding the melting point of 240 ° C. of lead-free solder used during the soldering (soldering) process, for example, in the range of 260 to 288 ° C.

Resin flow in this specification means the degree of resin flow. For reference, if there is a lot of resin flow in the bonding sheet, excessive burr may occur during hole processing, and as a result, an additional desmear process may be required.

In this specification, in the thermal expansion coefficients (CTE α1, α2), α1 is the CTE (coefficient of thermal expansion) value of the linear section at a temperature below Tg, and α2 is the CTE (coefficient of thermal expansion) value of the linear section at a temperature higher than Tg. it means

In this specification, rheological viscosity means a viscosity value (Pa.s) required for weldability.

In this specification, weldability means adhesiveness at the time of temporary bonding before complete bonding through a press process. In addition, the bonding process means a process of temporary bonding before complete bonding through a press process. The bonded specimens are completely bonded through the press process, and the bonding strength after complete bonding is called the original bonding strength.

Description of Exemplary Embodiments

In exemplary embodiments of the present invention, an LCP filler having a specific particle diameter distribution or a filler including the corresponding LCP filler is included in a certain amount in the polyolefin-based low dielectric adhesive composition.

Specifically, in exemplary embodiments of the present invention, as a polyolefin-based low dielectric adhesive composition, an LCP filler having a particle size D50 of 5 to 15 μm or a filler including the LCP filler is used in an amount of 20 to 50 wt% of the total weight of the composition. It provides a polyolefin-based low dielectric adhesive composition comprising.

Here D50 can be measured using a laser particle size analyzer.

If the D50 is greater than the range of 5 to 15 μm, unevenness of the coating surface and consequently poor appearance may occur during adhesive coating (coating). In addition, it is difficult to grind the LCP filler when it is less than 5 μm.

In an exemplary embodiment, a thermotropic type may be used as the LCP filler. For reference, there are two types of LCP, for example, a concentration transition type (Lyotropic) type and a temperature transition type (Thermotropic type), of which the one applicable as a filler is the thermotropic type.

In an exemplary embodiment, the LCP filler may have a Tm (melting temperature) of 300 to 340 °C, preferably 320 °C. In addition, the LCP filler has a dielectric constant (Dk, based on 10 GHz) of 3.3 to 3.7, or 3.4 to 3.6, or preferably 3.5, and a dielectric loss tangent (Df, based on 10 GHz) of 0.0008 or less, preferably 0.0007.

In an exemplary embodiment, the LCP filler or the filler including the corresponding LCP filler may be used in an amount of 20 to 50% by weight, or 25 to 45% by weight, or 30 to 40% by weight. For example, the LCP filler or the filler containing the corresponding LCP filler is 20% by weight or more, 22% by weight or more, 24% by weight or more, 26% by weight or more, 28% by weight or more, 30% by weight or more, 32% by weight or more, 34% by weight or more % or more, 36% or more, 38% or more, 40% or more, 42% or more, 44% or more, 46% or more, 48% or more, or 50% or less, 48% or more % or less, 46% or less, 44% or less, 42% or less, 40% or less, 38% or less, 36% or less, 34% or less, 32% or less, 30% or less, 28% or less % or less, 26% or less, 24% or less, 22% or less may be used.

If the LCP filler or the filler containing the LCP filler exceeds 50% by weight, the peel strength with the adherend may be lowered, and the required peel strength level (0.7 kgf/ cm) can be obtained

In an exemplary embodiment, a silica filler may be additionally mixed and used as the filler in addition to the LCP filler. Even when silica fillers are mixed and used, the total filler is used so that it is 20 to 50 wt%. For reference, in the case of Example 1, 40% by weight of the LCP filler alone was used, and in the case of Example 2, 20% by weight of the LCP filler and 20% by weight of the silica filler were mixed and used.

In an exemplary embodiment, the LCP filler and the silica filler may be mixed and used in a weight ratio of 4:6 to 6:4, preferably 5:5.

In an exemplary embodiment, the composition includes 20 to 50 wt% of the above-described LCP filler or a filler including the corresponding LCP filler, 40 to 80 wt% of a polyolefin resin, 0.1 to 10 wt% of an epoxy resin, 0.1 to 10 wt% of an epoxy curing agent, and the rest of the catalyst. (For example, 0.1 wt%). Peel strength may be lowered when the LCP filler or the filler containing the LCP filler is used in excess of 50wt%. When the epoxy resin is used in excess of 10wt%, the dielectric constant (Dk) and dielectric loss tangent (Df) values increase, and dielectric performance may deteriorate. When using an epoxy curing agent in excess of 10wt%, an unreacted curing agent may remain and affect adhesion, resin flow, dielectric performance, and heat resistance. When using a catalyst content of more than 0.1wt%, pot life (adhesive usable time, Pot-life) may be shortened.

In an exemplary embodiment, the polyolefin resin may be at least one copolymer, terpolymer, or tetrapolymer selected from the group consisting of ethylene, propylene, butylene, butene, butadiene, octene, and styrene.

In an exemplary embodiment, the epoxy resin curing agent may be at least one selected from an amine-based curing agent, a phenol-based curing agent, an isocyanate-based curing agent, and an active ester curing agent.

In an exemplary embodiment, the composition has a dielectric constant (Dk, based on 10 GHz) of 2.1 to 2.7, or 2.2 to 2.6, or 23 to 2.5, or preferably 2.4, and a dielectric loss tangent (Df, based on 10 GHz) of 0.0015 or less. , or 0.0014 or less, or 0.0013 or less, or 0.0012 or less, or 0.0011 or less, preferably 0.0010.

In an exemplary embodiment, the composition has a contact temperature of 34000 Pa.s or less, or 33000 Pa.s or less, or 32000 Pa.s or less, more preferably 31000 Pa.s or less from a temperature of 140 ° C. to a temperature of 160 ° C. , or 30000 Pa.s or less, 29000 Pa.s or less, or 28000 Pa.s or less, 27000 Pa.s or less, or 26000 Pa.s or less, 25000 Pa.s or less, or 24000 Pa.s or less, 23000 Pa. s or less, or 22000 Pa.s or less, 21000 Pa.s or less, or 20000 Pa.s or less, 19000 Pa.s or less, or 18000 Pa.s or less, 16000 Pa.s or less, or 15000 Pa.s or less there is. or greater than 14000 Pa.s, greater than 15000 Pa.s, greater than 16000 Pa.s, greater than 17000 Pa.s, greater than 18000 Pa.s, greater than 19000 Pa.s, greater than 20000 Pa.s, greater than 21000 Pa.s, 22000 Pa.s or more, 23000 Pa.s or more, 24000 Pa.s or more, 25000 Pa.s or more, 26000 Pa.s or more, 27000 Pa.s or more, 28000 Pa.s or more, 29000 Pa.s or more, 30000 Pa. s or more, 31000 Pa.s or more, 32000 Pa.s or more, or 33000 Pa.s or more.

Additionally, the adhesive composition according to exemplary embodiments of the present invention may contain, if necessary, a dehydrating agent, a plasticizer, a weathering agent, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a bleaching agent, a colorant, a conductive agent, a release agent, a surface treatment agent, and a viscosity agent. Additives such as flame retardant fillers such as regulators and phosphorus flame retardants can be further blended.

On the other hand, Figure 1 is a schematic diagram showing the configuration of the bonding sheet layer in an exemplary embodiment of the present invention.

As shown in FIG. 1, in an exemplary embodiment of the present invention, a base film 10 such as a polyethylene terephthalate (PET) film, the above-described polyolefin-based adhesive layer 20, and a release layer 30 of a three-layer structure A bonding sheet is provided.

To manufacture the bonding sheet, a polyethylene terephthalate (PET) film (base film for coating) is used as a base film, for example. Such a base film preferably has a thickness of, for example, 25 to 75 μm. If the thickness of the substrate is too thin, it can be easily wrinkled, making it difficult to handle, and if it is too thick, it may become bulky and difficult to handle, and manufacturing cost may also increase.

Meanwhile, the above-described polyolefin-based adhesive is coated on the base film. At this time, the thickness of the adhesive layer is preferably to have a thickness of 10 ~ 100㎛. If the thickness of the polyolefin-based adhesive layer is less than 10㎛, the adhesive strength may decrease when bonding to an insulating film such as a copper circuit or a polyimide film due to the insignificant thickness, and the filling in the copper circuit area Failure to do so may result in poor heat resistance. Conversely, when the thickness of the polyolefin-based adhesive layer exceeds 100 μm, it becomes a factor in cost increase, and in thin film FPCBs that require flexibility, the bending radius is small due to the excessively thick thickness, which may cause a decrease in flexibility.

On the other hand, a release layer for protection is laminated on the polyolefin-based adhesive layer described above. The release layer is to serve as a protective film for protection from foreign matter during the FPCB manufacturing process. The release layer is laminated using a release material, and as a release material, for example, a release film and a release paper (release paper) may be mainly used.

In a non-limiting example, as the release paper, PE-coated, PP-coated, or PP laminated paper may be used, and release paper coated with a release agent for peeling may be used, if necessary. It has excellent punchability and considers the peel strength, etc., and selects the thickness, coating material, and release agent and applies it as a release material.

When the polyolefin-based adhesive is coated on the base film, for example, by using one or more coating processes such as gravure coating, micro gravure coating, spin coating, screen printing, comma coating, and die coating After the polyolefin-based adhesive is applied on a base film and dried, a release material (eg, a release film or release paper) may be laminated.

On the other hand, the bonding sheet manufactured in this way is applied as an adhesive layer for forming multilayer circuits in manufacturing FPCB.

It is used to peel off the base film or release material of the bonding sheet and attach the polyolefin adhesive side to the insulation layer side or circuit side of the flexible printed circuit board (FPCB) and laminate it. FPCB products are manufactured by pressing through

In a non-limiting example, the hot-press condition may be performed under a temperature condition of, for example, 140 to 185° C. for about 30 minutes to 2 hours, and a surface pressure of about 20 to 50 kg.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as being limited by these examples.

[Production and test examples]

Examples and Comparative Examples were prepared and measured with the same composition as the following [Table 1].

manufacturing method

As shown in the table below, a thermotropic LCP (D50 5-15um) is added as a filler to a mixture containing a polyolefin resin, an epoxy resin, an epoxy curing agent, and a catalyst, and mixed.

Comparative Example 1 is the case where only the silica filler is used, and Comparative Example 2 is the same as Example 1, but D50 10-20um outside the D50 5-15um is used. Comparative Example 3, unlike Examples 1 and 2, is a case of using an excessive amount of 60 wt% out of 20 to 50 wt%.

In all of the prepared Examples 1 and 2 and Comparative Example 1, low-dielectric bonding sheets having a thickness of 25 μm were prepared and physical properties were evaluated. Each physical property measurement / evaluation method is as follows.

Permittivity and dielectric loss tangent measurement

Remove the release PET and release material (release paper) from the bonding sheet, take only the semi-hardened (B-stage) adhesive, and make it into a fully cured (C-stage) state with heat and pressure. The specimen was cut into a size of 40 mm x 40 mm and measured by the SPDR method using keysight Network Analyzer equipment to measure the dielectric constant (dielectric constant) value and the dielectric loss factor (Loss tanδ value) on a frequency of 10 GHz.

Adhesion evaluation

The adhesion of the bonding sheet was measured by inserting the bonding sheet between the copper foil and the polyimide film and bonding them by applying heat and pressure, then cutting the specimen into a width of 10 mm and measuring the peel strength using a 90 ° Peel strength tester.

It is preferable that the adhesive force has a Peel Strength value of 0.7 kgf/cm or more. If it is lower than this, it is because there is a high possibility of causing problems such as peeling and lifting.

Soldering heat resistance evaluation

The heat resistance of the soldering of the bonding sheet is measured by inserting the bonding sheet between the copper foil and the polyimide film and bonding them by applying heat and pressure. was evaluated, and the results were indicated as ○ (tolerable) and × (not tolerable).

For soldering heat resistance, products can be produced only when they have heat resistance that can withstand the process temperature of 260 ℃ during the SMT mounting process. Float the product in a lead bath and hold it at 288 ℃ for 10 seconds if there is no abnormality in lifting and swelling, it is considered to be endurable.

Resin flow evaluation

After thermally bonding the bonding sheet (adhesive layer) to the PI (polyimide) film, it was punched into a circular shape with a diameter of 3 to 10 mm and hot-pressed with FCCL. The extent to which the adhesive came out of the PI film was measured.

For reference, in the case of a bonding sheet having a thickness of 25 μm, a resin flow of 100 μm or less is required. If it is higher than this, the hole processing process may not be smooth due to excessive flow of resin in the hole.

Thermal expansion coefficient evaluation

CTE (ppm/°C) values were measured in the temperature range of 25°C to 200°C under a heating rate of 5 to 10°C/min and a weight of 0.1 N using TMA equipment. CTE - The CTE section before Tg was denoted as α1, and the CTE section above Tg was denoted as α2. The smaller the CTE, the less mismatching during deformation and multilayer stacking of FPCB products.

Rheological viscosity evaluation

The adhesive films obtained in Examples and Comparative Examples were laminated using a rubber roll laminator to a thickness of 800 μm. After preparing an 8mm circular specimen of this film, the viscosity was measured using TA's ARES-G2, and the results are shown in Table 1.

The ARES-G2 measurement conditions are a heating rate of 20°C/min, a strain of 5%, an angular frequency of 5.0 rad/s, and an axial force of 1N.

In terms of weldability, the lower the rheological viscosity, the better. It may have a viscosity of 14000 Pa.s to 45000 Pa.s from a temperature of 140° C. to a temperature of 185° C. (maximum possible hot press temperature), but preferably a viscosity of 34000 Pa.s from a temperature of 140° C. to a temperature of 160° C. It is preferable to have a viscosity of Pa.s or less, more preferably 31000 Pa.s or less.

composition Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 LCP filler 40.0 20.0 - 40 60 silica filler - 20.0 40.0 - - polyolefin resin 50.0 50.0 50.0 50 30 epoxy resin 8.0 8.0 8.0 8.0 8.0 curing agent 1.9 1.9 1.9 1.9 1.9 catalyst 0.1 0.1 0.1 0.1 0.1 Dk (@10GHz) 2.40 2.43 2.45 2.40 2.37 Df (@10GHz) 0.0010 0.0014 0.0020 0.0010 0.0008 Adhesion (kgf/cm) 1.2 1.3 1.5 0.9 0.3 Soldering heat resistance (288℃, sec) O
60↑ O
60↑ O
60↑ O
30 X
5 Resin flow (um) 96 91 83 176 42 CTE α1,α2 (ppm) 222, 360 185 , 329 156, 311 220 , 357 183, 321 Rheology Viscosity 31000Pa.s 22000Pa.s 14000Pa.s 32000Pa.s 41000Pa.s

As can be seen from the above, Examples 1 and 2 and Comparative Example 1 all implement the characteristics of the low dielectric bonding sheet. However, there is a difference in Dk and Df values. The Df value of Example 1 containing all the LCP fillers was the lowest at 0.0010.

As such, in the exemplary embodiments of the present invention, it was possible to obtain basic physical properties as a bonding sheet and obtain a very good Df value by introducing a specific LCP filler.

Comparative Example 2 is a case of using D50 10-20um out of D50 5-15um, and it can be seen that the resin flow increases due to the LCP filler with a large particle size distribution and the coating surface is non-uniform, resulting in lower heat resistance and adhesion. Comparative Example 3 is a case of using 60 wt%, which is out of 20 to 50 wt%, and has the advantage of improving dielectric performance and reducing resin flow, but it can be seen that adhesion, heat resistance, and weldability are greatly reduced.

The embodiments of the present invention described above should not be construed as limiting the technical spirit of the present invention. The protection scope of the present invention is limited only by the matters described in the claims, and those skilled in the art can improve and change the technical spirit of the present invention in various forms. Therefore, these improvements and modifications will fall within the protection scope of the present invention as long as they are obvious to those skilled in the art.

Claims (7)

As a polyolefin-based low dielectric adhesive composition,
LCP filler having a particle distribution D50 of 5 to 15 μm or 20 to 50 wt% of a filler containing the corresponding LCP filler,
Epoxy resin 0.1~10wt%,
Epoxy curing agent 0.1~10wt%,
Catalyst 0.1wt% or less, and
A polyolefin-based low-k adhesive composition, characterized in that composed of 40 wt% or more of a polyolefin resin.
According to claim 1,
The LCP filler has a Tm (melting temperature) of 300 to 340 ° C,
The permittivity (Dk, based on 10 GHz) is 3.3 to 3.7,
A polyolefin-based low dielectric adhesive composition, characterized in that the dielectric loss tangent (Df, based on 10 GHz) is 0.0008 or less.
According to claim 1,
As the filler, a silica filler is further included in addition to the LCP filler,
The polyolefin-based low dielectric adhesive composition, characterized in that the LCP filler and the silica filler are mixed in a ratio of 4: 6 to 6: 4 by weight.
delete According to claim 1,
The composition has a dielectric constant (Dk, based on 10 GHz) of 2.1 to 2.7, and a dielectric loss tangent (Df, based on 10 GHz) of 0.0015 or less.
base film;
A polyolefin-based adhesive layer made of the polyolefin-based adhesive composition according to any one of claims 1 to 3 and 5; and
A bonding sheet characterized in that a release layer is laminated.
A printed circuit board, characterized in that a polyolefin-based adhesive layer made of the polyolefin-based adhesive composition according to any one of claims 1 to 3 and 5 is formed on the insulating layer surface or circuit surface of the printed circuit board.

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