KR100899720B1 - Adhesive filim for die attachment and resin composition for the same - Google Patents

Abstract

The present invention relates to a resin composition for a die bonding film obtained by mixing a phenoxy resin and an amorphous epoxy resin in a predetermined ratio, and a die bonding film using the same. In the resin composition of the present invention, the sum of the phenoxy resin (X) and the crystalline epoxy resin (Y) is 10-30 wt%, 10-30 wt% of the rubber resin having a weight average molecular weight of 50,000 or more, and 10-50 wt% of the liquid epoxy resin. And 5 to 20 parts by weight of a phenol resin curing agent based on 100 parts by weight of a base resin composed of 10 to 40% by weight of a cresol novolac epoxy resin. In this case, the phenoxy resin (X) has a weight average molecular weight of 10,000 or more, and the weight ratio of the phenoxy resin (X) and the crystalline epoxy resin (Y) is X / Y = 0.5 to 2.

Die Adhesive Films, Compositions, Voids, Reliability, Amorphous Epoxy

Description

Adhesive filim for die attachment and resin composition for the same

The present invention relates to a die bonding film for a printed circuit board and an adhesive resin composition thereof. More specifically, the present invention relates to a resin composition for a die adhesive film composed of a resin mixture containing a phenoxy resin and an amorphous epoxy resin and a die adhesive film using the same.

As semiconductor devices become more versatile and lighter and shorter, multi-layer package devices, a new type of packaging technology such as multichip packaging or system-in-packaging, have emerged in the semiconductor assembly industry. One of the key technologies in such packaging is to stack chips of the same or different size. The type of packaging in which chips are stacked and similar in size to chips is called stack chip scale packaging (SCSP).

In such a multi-layered packaging process, it is very important to closely bond a printed circuit board (PCB) made of an organic material located at the bottom of the semiconductor device and a silicon chip made of an inorganic material such as silicon. For smooth bonding, an adhesive with excellent adhesion to both organic and inorganic surfaces is essential, which overcomes the step of the printed circuit board.

Conventionally, a paste-type adhesive is used as a die adhesive, but in this case, the process is complicated, thickness control is difficult when the adhesive is applied, a problem of bleeding occurs, and a wafer-level process is impossible. Paste adhesives could not overcome the PCB step or had sufficient adhesion to both organic and inorganic materials. Therefore, in recent years, film type die adhesive has been used as a multi-layer packaging adhesive.

Adhesive films used in the SCSP is divided into three types depending on the application. Die-to-Die adhesive film for stacking chips of different sizes, spacers for stacking chips of the same size, and die-stick for bonding chips on a substrate Distinguished for substrate (Die-to-Substrate). The substrate may be a PCB packaging substrate or may be a leadframe. The recent trend is to use die-to-substrate adhesive films for die-to-die and leadframe as well.

In this field, efforts have been made to find a material having high reliability and excellent adhesion as a die adhesive film for a multi-layer package and an adhesive resin composition therefor.

The technical problem of the present invention is to develop a die adhesive film having high flexibility and high reliability, and an adhesive resin composition therefor, which can fill the step of the PCB due to its flexibility.

In order to achieve the above object, in the present invention, the sum of the phenoxy resin (X) and the crystalline epoxy resin (Y) is 10 to 30% by weight, 10-30% by weight of a rubber resin having a weight average molecular weight of 50,000 or more, liquid epoxy resin 10 It provides the resin composition for die adhesion films containing 5-20 weight part of phenol resin hardening | curing agents with respect to 100 weight part of basic resin which consists of -50 weight% and 10-40 weight% of cresol novolak epoxy resins. In this case, the phenoxy resin (X) has a weight average molecular weight of 10,000 or more, and the weight ratio of the phenoxy resin (X) and the crystalline epoxy resin (Y) is X / Y = 0.5 to 2.

In the resin composition of the present invention, the phenoxy resin is preferably a glass transition temperature of 100 ℃ or less. On the other hand, the crystalline epoxy resin is suitable for the epoxy resin having a melting point of 80 ~ 120 ℃ ℃ and a viscosity at 150 ℃ 0.5 poise or less.

The resin composition of the present invention may further comprise a silane coupling agent and / or a silica filler on the one hand.

Moreover, in this invention, the die adhesion film manufactured using such a resin composition for die adhesion films is provided.

The resin composition for die adhesion films of this invention has the moisture resistance reliability more than the level of JEDEC standard 2A (Level 2A), and is excellent in the ability to fill the level | step difference of a board | substrate, and can make pore area less than 10% with respect to chip area.

The composition of the resin composition for a die-bonding film provided by the present invention is characterized by including 5 to 20 parts by weight of a phenol resin curing agent and optionally 3 to 20 parts by weight of a silica filler and a silane coupling agent based on 100 parts by weight of the basic resin. .

The base resin is 10-30% by weight of the sum of the phenoxy resin (X) and the crystalline epoxy resin (Y), 10-30% by weight of the rubber resin having a weight average molecular weight of 50,000 or more, 10-50% by weight of the liquid epoxy resin and cresol Novolak epoxy resin 10 to 40% by weight, wherein the phenoxy resin (X) has a weight average molecular weight of 10,000 or more, the weight ratio of the phenoxy resin (X) and the crystalline epoxy resin (Y) is 0.5 ~ It is characterized by two.

In the present invention, phenoxy resin refers to a thermoplastic polymer having a phenolic functional group at its end. The phenoxy resin component in the resin composition for die adhesion films of the present invention increases the moisture resistance reliability and imparts adhesion to the PCB. Some examples of the phenoxy resins of the invention include the PKHB, PKHC, and PKHJ family of InchemRez® phenoxy resins from InChem, USA. Typical PKHB, PKHC, and PKHJ have weight average molecular weights of 32000, 43000 and 57000, respectively, and you can choose the right one for your application. The phenoxy resin of the present invention is preferably a phenoxy resin having a weight average molecular weight of 10,000 or more and a glass transition temperature (T _g ) of 100 ° C or less. Phenoxy resins having a weight average molecular weight of less than 10,000 are not suitable because the moisture resistance reliability is lowered. If the glass transition temperature exceeds 100 ℃, there is a disadvantage that the fillability to fill the PCB step is reduced.

In the present invention, the crystalline epoxy resin refers to an existing bisphenol-based epoxy having a softening point and an epoxy resin having a liquid crystal characteristic having a melting point at a specific temperature. In the composition of the present invention, filling and reliability Take on the role of improving. Some examples of such crystalline epoxy resins include Tohto Kasei Co., Ltd. YSLV series and biphenyl epoxy resins. It is preferable that the crystalline epoxy resin of the present invention has a melting point of 80 to 120 ° C., but a melting point of less than 80 ° C. results in poor film handleability, and even if the melting point exceeds 120 ° C., the performance of filling the step difference of the substrate is not good. In addition, the crystalline epoxy resin of the present invention preferably has a viscosity at 150 ° C of 0.5 Poise or less, but when the viscosity is larger than this value, handling becomes inconvenient.

If less than the phenoxy resin and the crystallinity is 10% by weight of the total amount of epoxy resin in the base can doing becomes frequent occurrence of burr (burr) from the die-bonding process, in Fig inorganic silicon wafer when more than 30% by weight It is undesirable because the adhesion of the die attach film to the film becomes weak and the ability to fill the substrate step is reduced.

When the weight of the phenoxy resin having a molecular weight of 10,000 or more is X and the weight of the crystalline epoxy resin is Y, the ratio of X and Y is preferably in the range of X / Y = 0.5 to 2. When the phenoxy resin and the amorphous epoxy resin are mixed in this way, physical properties such as flexibility, reliability, and adhesive force required for the die-bonding film can be properly adjusted. In this case, when the X / Y is more than 2, the film can fill the step of the substrate. If it falls, if it is less than 0.5, moisture resistance reliability falls.

In the present invention, the rubber resin having a molecular weight of 50,000 or more serves to extinguish the stress applied to the adhesive by increasing adhesion and adding elasticity. Examples of suitable rubber resins include acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR) or hydrogenated acrylonitrile-butadiene rubber (H-NBR). When the content range of the rubber resin in the resin composition for die-bonding film of the present invention is less than 10% of the weight of the basic resin, the required degree of elasticity cannot be obtained and the film is weak to impact. In addition, even if the rubber resin content exceeds 30% of the basic resin weight, the heat resistance is weakened, so this value is appropriate as an upper limit.

In the present invention, the liquid epoxy resin is used to improve the degree of crosslinking and impart adhesion to the film. For this purpose, bisphenol A-based, bisphenol-F-based and / or rubber-modified epoxy resins are suitable. The average person skilled in the art will be able to easily determine through experiments the type and content of the specific liquid epoxy resin needed for the specific use of the die attach film. The liquid epoxy resin in the base resin is suitably occupy 10 to 50% by weight. If the content is less than 10% by weight, the adhesion of the film is insufficient, and if it exceeds 50% by weight it is not preferable because it becomes vulnerable to thermal shock.

In the present invention, the cresol novolac epoxy resin is an epoxy functional group (particularly a glycidyl group) is introduced into the phenol resin polymerized with cresol and formaldehyde, and plays a role of improving heat resistance in the resin composition. When the weight ratio of the cresol novolac epoxy resin in the base resin of the present invention is less than 10%, the adhesion and heat resistance are reduced. On the contrary, if the content exceeds 40% by weight, there is a problem of being a die-bonding film vulnerable to impact. In the present invention, the softening point of the cresol novolac epoxy resin is preferably 60 to 100 ° C., because it improves the fillability and adhesion to the wafer.

Meanwhile, the resin composition of the present invention may optionally include 3 to 20 parts by weight of a filler based on 100 parts by weight of the base resin in order to improve moisture resistance and control thermal expansion. Suitable fillers include silica. Adding more than 20 parts by weight of a filler, such as silica, results in poor flexibility and poor adhesion to the wafer. On the contrary, when the filler content is less than 3 parts by weight, the moisture resistance is insufficient.

The resin composition for die adhesion films of this invention uses a phenol resin series hardening | curing agent, and can use a hardening accelerator selectively. As the phenol resin-based curing agent, it is preferable to use one substance selected from the group consisting of phenol novolac, cresol novolac and bisphenol A novolac resin or a mixture of two or more kinds. As the curing accelerator, one substance or a mixture of two or more selected from the group consisting of amine-based, phenol-based and imidazole-based curing accelerators can be used. In the present invention, when the content of the phenol resin-based curing agent is lower than 5 parts by weight, the crosslinking degree is low, the adhesive strength is lowered, and when the content is higher than 20 parts by weight, there is a disadvantage in that the preservation of the composition is lowered and the moisture resistance reliability is lowered.

The resin composition for die adhesion films of this invention can contain a silane coupling agent other than this. The average person skilled in the art will be able to easily determine through experiments the specific silane coupling agent material and content required for the use of the die attach film.

In this invention, it also provides the die adhesion film manufactured using the said resin composition for die adhesion films. The die adhesive film of the present invention can be prepared through the process of applying the resin composition of the present invention on a release-treated PET film and drying. The average person skilled in the art will be familiar with the process of manufacturing the die adhesive film by coating the adhesive resin composition on a suitable plastic film, and thus, the detailed description thereof will be omitted. Briefly referring to the film manufacturing process, the adhesive resin composition is applied on a release-treated plastic film (for example, PET) to a certain thickness by using a method such as gravure or rip coating. The film to which the composition is applied is passed through a coater chamber and dried under constant temperature and pressure.

<Example>

The present invention will be described in more detail with reference to the following Examples. The average person skilled in the art to which the present invention pertains may change the present invention in various other forms in addition to the embodiments described in the following examples, and the following examples merely illustrate the present invention, and the scope of the technical spirit of the present invention is given below. It is not to be construed as limiting the scope of the examples.

The composition ratio of each component of the composition for die adhesion films of the present invention In order to determine the effect of the composition according to the present invention was prepared as shown in Table 1 below and compared with the comparative composition. Each of the compositions of Comparative Examples 1 to 4 has the same components as the Example compositions, but the content range of one of the components is outside the range defined in the claims below (components outside the content range are shown in Table 1 below). Bold italicized). In Table 1 below, the amounts of the filler, the silane coupling agent, the phenol resin curing agent, and the curing accelerator are added in amounts corresponding to 10, 1, 10, and 0.1 parts by weight, respectively, when the total weight of the base resin is converted into 100.

Composition (parts by weight) Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Phenoxy Resin (X) ^* 10 15 10 20 5 20 5 Crystalline Epoxy ^** (Y) 20 10 10 20 5 5 20 X + Y 30 25 20 40 10 25 25 X / Y 0.5 1.5 One One One 4 0.25 Rubber resin ^*** 30 30 30 20 50 25 25 Liquid Epoxy Resin ^† 20 20 20 20 20 35 35 Cresol Novolak Resins ^‡ 20 25 30 20 20 15 15 Fillers ^‡‡ 10 10 10 10 10 10 10 The silane coupling agent ^§ 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Phenolic Resin Curing ^{Agent §§} 10 10 10 10 10 10 10 Curing accelerator ^§§§ 0.1 0.1 0.1 0.1 0.1 0.1 0.1

* InchemRez PKHB of InChem Corporation, USA with a weight average molecular weight of 32,000

** YSLV-09CR from Tohoto Kasei, Japan, with melting point of 89 ℃

*** NBR having a molecular weight of 100,000.

† Bisphenol A liquid epoxy resin with an epoxy equivalent of 200

‡ Cresol novolac epoxy resin with a softening point of 80 ° C. and an epoxy equivalent of 300

‡‡ Silica (particle size 100 ~ 300nm)

§ (glycidoxypropyl) trimethoxy silane

§§ D.E.H. 85

§§§ 2-methylimidazole

As can be seen in Table 1, the comparative example is only one component is slightly out of the composition content range according to the present invention and the remaining components and contents are the same as the examples. Examples and Comparative Examples Prepared according to Table 1 A film for die bonding and a specimen in which a chip was bonded to a PCB were prepared using the film. The method for producing a die-bonding film from the adhesive resin composition and the chip packaging using the film are well known to those skilled in the art and will not be described in detail here. Briefly, the resin composition is dissolved in methyl ethyl ketone (MEK) solvent, and then coated on a release-treated polyethylene terephthalate (PET) film by using a gravure or lip coating, etc., to a thickness of 60 μm. Then dried at 80 ° C. for 5 minutes. The PET film coated with the composition was passed through a coater chamber to laminate another PET protective film to obtain a die bonding film having a final thickness of 20 μm.

Then, after attaching the adhesive film of the Example or Comparative Example prepared as described above to the wafer, it was cut into 7 mm × 7 mm to obtain a chip specimen. The chip with the adhesive film was bonded onto the PCB. Bonding was accomplished by applying a load in 3 kg at 150 ° C. for 2 seconds. At this time, the roughness difference of the PCB surface is 15 micrometers. The bonded substrate bonded specimens were cured at 175 ° C. for 1 hour.

Bonding force evaluation was performed on the substrate bonding specimens thus obtained, and the results are summarized in Table 2 below. The adhesion strength was evaluated by observing the moisture resistance and the porosity of the substrate after adhesion. The evaluation method is as follows.

Moisture resistance reliability / Porosity evaluation method after adhesion

The reliability of the chip specimens was evaluated using a moisture resistance test according to the Joint Electronic Device Engineering Council (JEDEC) level 2A specification, which is an industry organization for the standardization of electronic device components in the United States. The substrate-bonded specimen, in which the chip is bonded with an adhesive film on the PCB, is left in a constant temperature and humidity chamber at 60 ° C. and 60% relative humidity for 5 days to absorb water, and then passed through a reflow oven at a peak temperature of 260 ° C. Reliability was tested by whether cracks or delamination occurred between the film and the PCB or between the film and the wafer.

Porosity evaluation of the substrate-bonded specimens was made by measuring the area of voids relative to the area of the hardened chip.

Evaluation item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparison 3 Comparative Example 4 Moisture Resistance (level 2A) pass pass pass fail fail pass fail Porosity after Bonding 3.1% 7.5% 5% 30% 5% 30% 10%

The data of Table 2 shows the outstanding adhesive force which the resin composition for die adhesion films of this invention has, and the importance of the composition for demonstrating such adhesive force. While the example specimens according to the resin composition of the present invention simultaneously satisfy the 2A level reliability of the JEDEC specification and the porosity of less than 10%, the comparative specimens are only slightly deviated from the content of only one component in the composition of the present invention. No composition met both criteria.

Specifically, Comparative Example 1 is a configuration in which the total total amount of the phenoxy resin (X) and the crystalline epoxy resin (Y) exceeds the upper limit of the present invention, and both the bonding strength and the void filling property of the die-bonding film to the silicon wafer are poor. It was. The comparative example 2 is a case where the sum of X + Y is a minimum value of a reference value, and a rubber resin exceeds the upper limit, but the porosity is excellent but it is unreliable. Comparative Example 3 can be seen that the ability to fill the step of the substrate is inferior because X is excessive compared to Y. On the contrary, Comparative Example 4 is a case where X is less than Y, and the porosity is good, but it can be seen that there is a problem in the moisture resistance reliability. In contrast, the example film specimens showed that the porosity was particularly low after adhesion, so the ability to fill the step of the substrate was very excellent.

From these example data, it can be seen that the resin composition for a die adhesive film of the present invention and the die adhesive film using the same have excellent bonding strength to both the PCB and the silicon wafer.

The terminology used in the description and examples herein is for the purpose of describing the invention in detail to those skilled in the art, and is intended to limit the scope of the invention in any particular sense or in the claims. It was not intended.

Claims (12)

The sum of the phenoxy resin (X) and the crystalline epoxy resin (Y) is 10-30 wt%; 10 to 30% by weight of a rubber resin having a weight average molecular weight of 50,000 or more; 10 to 50% by weight of the liquid epoxy resin; And With respect to 100 parts by weight of the base resin consisting of 10 to 40% by weight of cresol novolac epoxy resin, 5 to 20 parts by weight of a phenol resin curing agent, The said phenoxy resin (X) has a weight average molecular weight of 10,000 or more, and the weight ratio X / Y of the said phenoxy resin (X) and a crystalline epoxy resin (Y) is 0.5-2, The resin for die adhesion films characterized by the above-mentioned. It is a composition, The resin composition for die adhesion films. The method of claim 1, The said phenoxy resin is 100 degrees C or less of glass transition temperature, The resin composition for die adhesion films characterized by the above-mentioned. The method of claim 1, The said crystalline epoxy resin is an epoxy resin whose melting | fusing point is 80-120 degreeC and the viscosity in 150 degreeC is 0.5 Poise or less, The resin composition for die adhesion films characterized by the above-mentioned. The method of claim 1, wherein the rubber resin, At least one material selected from the group consisting of acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR) and hydrogenated acrylonitrile-butadiene rubber (H-NBR) It is a mixture, The resin composition for die adhesion films. The method of claim 1, wherein the liquid epoxy resin, It is one substance selected from the group which consists of a bisphenol A system, a bisphenol F system, and a rubber modified epoxy resin, or a mixture of 2 or more types, The resin composition for die adhesion films characterized by the above-mentioned. The method of claim 1, The said cresol novolak epoxy resin has a softening point of 60-100 degreeC, The resin composition for die adhesion films characterized by the above-mentioned. The method of claim 1, wherein the phenol resin curing agent, A resin composition for a die-bonding film, characterized in that it is one substance selected from the group consisting of a phenol novolak resin, a cresol novolak resin, and a bisphenol A novolak resin or a mixture of two or more kinds. The method of claim 1, The said resin composition for die adhesion films further contains a hardening accelerator, The resin composition for die adhesion films characterized by the above-mentioned. The method according to claim 8, wherein the curing accelerator, It is one substance selected from the group which consists of an amine type, a phenol type, and an imidazole series hardening accelerator, or a mixture of 2 or more types, The resin composition for die adhesion films characterized by the above-mentioned. The method of claim 1, The resin composition for die adhesive films further comprises 3 to 20 parts by weight of a silica filler based on 100 parts by weight of the base resin. The method of claim 1, The said resin composition for die adhesion films further contains a silane coupling agent, The resin composition for die adhesion films characterized by the above-mentioned. The die adhesion film manufactured using the resin composition for die adhesion resin films of any one of Claims 1-11.