KR101036353B1 - Screen Printable Adhesive Paste for Semiconductor Packaging - Google Patents

Abstract

Provided is an adhesive paste composition for screen printing, which is an adhesive paste composition for manufacturing a semiconductor device, which does not require B-staging. The adhesive paste composition of the present invention comprises 10 to 25% by weight of epoxy resin, 40 to 70% by weight of inorganic filler, 5 to 15% by weight of rubber, 5 to 20% by weight of curing agent and 5 to 10% by weight of lactone plasticizer. Include. The lactone plasticizer in the composition of the present invention is a 5-7 member ring compound that can cause a ring opening reaction at a temperature of 100 ℃ ~ 150 ℃. And the weight ratio of the epoxy resin and the inorganic filler is epoxy resin: inorganic filler = 1: 2 to 1: 7, and the weight ratio of the plasticizer and the epoxy resin is in the range of epoxy resin: plasticizer = 1: 1 to 5: 1.

Description

Screen Printable Adhesive Paste for Semiconductor Packaging

The present invention relates to an adhesive paste composition for manufacturing a semiconductor device, and more particularly, to an adhesive paste composition for manufacturing a semiconductor device capable of screen printing.

In general, a semiconductor packaging process is a wafer dicing process in which a wafer is cut into unit semiconductor chips (or dies), and the die is cut into a chip mounting frame such as a lead frame, a printed circuit board, or a substrate such as a tape wiring board. Unit bonding of die bonding process, wire bonding process for electrically connecting chip and chip mounting frame, and epoxy molding compound process for sealing semiconductor chips and bonding wires It includes. In the packaging of semiconductor devices, a die attach paste is widely used as an adhesive for laminating chips on chips or adhering chips to supporting members such as PCBs or lead-frames.

The die bonding process is a process of bonding a semiconductor die to a substrate such as a lead frame or a printed circuit board. Commonly used bonding means for die bonding processes include conductive liquid adhesives, such as silver-epoxy, silver-glass, or solder, and non-conductive liquid adhesives without conductive materials. A certain amount of such a liquid adhesive is dropped on a substrate such as a lead frame, and a semiconductor die is placed on the substrate and pressed, and a conventional die bonding method (dispensing method) is performed. On the other hand, a screen printing method of applying a certain shape with a die adhesive paste and adhering a die on the coated paste has been newly applied.

Adhesive pastes for semiconductor packaging, which can be screen printed, are used in DRAM, multichip packages and wafer-level packages because of their fairness, reliability and low process costs. The adhesive paste for screen printing is usually attached to a semiconductor chip in a semi-cured state by B-staging printed on a substrate. When the paste is fully cured, the adhesion between the semiconductor chip and the substrate is maximized and the semiconductor packaging is completed through wire bonding and EMC process.

SUMMARY OF THE INVENTION An object of the present invention is to provide an adhesive paste composition for manufacturing a semiconductor device in the form of a screen printing that can exhibit high adhesion and reliability even without a non-staging step.

Adhesive paste composition of the present invention for solving the above technical problem is 10 to 25% by weight of epoxy resin, 40 to 70% by weight of inorganic filler, 5 to 15% by weight of rubber, 5 to 20% by weight of the curing agent and 5 ~ 15% by weight of lactone plasticizer. The lactone plasticizer in the composition of the present invention is a 5-7 member ring compound that can cause a ring opening reaction at a temperature of 100 ℃ ~ 150 ℃. And the weight ratio of the epoxy resin and the inorganic filler is epoxy resin: inorganic filler = 1: 2 to 1: 7, and the weight ratio of the plasticizer and the epoxy resin is epoxy resin: plasticizer = 1: 1 to 5: 1.

Suitable materials as lactone plasticizers of the present invention include γ-nonalactone, γ-undecalactone, glucono-α-lactone, γ-butyrolactone, and the like. In the epoxy resin of the present invention, the solid / liquid ratio is preferably solid phase: liquid phase = 1: 9 to 4: 6.

The adhesive paste composition for manufacturing a semiconductor device exhibits an adhesive force of 100 g / cm 2 or more to a semiconductor when screen printing without a non-staging step.

By using the adhesive paste composition for semiconductor device manufacture of this invention, a high level of adhesive force can be obtained even if a non-staging process is skipped, productivity improves and process management becomes easy.

Hereinafter, the present invention will be described in detail. The adhesive paste resin composition for semiconductor element manufacture provided by the subject solution of this invention consists of an epoxy resin, an inorganic filler, a lactone plasticizer, a rubber resin, and a hardening | curing agent.

General purpose epoxy resins may be used as the epoxy resins. Some examples of general purpose epoxy resins that may be used as the epoxy resins of the present invention include bisphenol A epoxy, bisphenol F epoxy, cresol novolac-based, phenoxy clock epoxy resins, and the like. And mixtures thereof. At this time, it is preferable that the mixing ratio of the solid phase and the liquid phase is 1: 9 to 4: 6 to maintain good rheological properties for adhesion reliability and printing. Regarding the mixing ratio of the solid phase and the liquid phase of the epoxy resin, the reliability of the adhesive paste may be insufficient when the solid phase component falls below the lower limit of the mixing ratio. When the solid phase epoxy component exceeds the above upper limit, the solubility of the epoxy is insufficient, and the screen printing property tends to be poor.

The epoxy resin accounts for 10 to 25% by weight of the total weight of the composition. If the amount of the epoxy resin in the total composition is less than the lower limit, the degree of curing decreases, which is not preferable. If the amount exceeds the upper limit, heat resistance lowers, which is not preferable.

Inorganic fillers in the compositions of the present invention increase moisture resistance and serve as a buffer against impact. The viscosity, thixotropy and reliability of the final paste can also be controlled by controlling the particle size, BET surface area and the like of the inorganic filler. Oxides are suitable as the inorganic filler. Examples of such oxides include spherical and plate-shaped silica (silicon dioxide) particles, aluminum oxide, antimony oxide, zinc oxide, magnesium oxide, and titanium oxide. In addition, silver powder and copper powder can also be used. The particle size of the inorganic filler may be 0.1 μm to 10 μm.

The inorganic filler comprises 40 to 70% by weight of the total composition. The inorganic filler acts as a moisture resistance and a buffer, and if the content is less than 40%, the product reliability is lowered, and if it exceeds 70%, the adhesive force is lowered, which is undesirable.

In one embodiment of the invention hydrophobic silica is used as the inorganic filler. Specifically, commercially available Degussa Co., Ltd. Aerosil Ry200, Aerosil Ry200s or Aerosil Rx200 can be used.

Lactone plasticizer in the composition of the present invention plays a role in controlling the viscosity of the composition and imparting adhesion, improving screen printing properties and the like. The lactone plasticizer of the present invention is a 5-7 membered ring which causes a ring opening reaction at a temperature of 100 ° C to 150 ° C. When the composition is heated to a temperature of 100 ℃ ~ 150 ℃ in the curing step after screen printing the lactone plasticizer of the present invention, the ring-opening reaction mainly binds to the hydroxyl groups present in the epoxy resin. In this reaction, when the lactone plasticizer is connected to the epoxy resin, the lactone does not volatilize during curing, thereby preventing voids or surface cracks that may occur during curing.

Some examples of such lactone plasticizers include γ-nonalactone, γ-undecalactone, glucono-α-lactone and γ-butyrolactone. In the composition of the present invention, the lactone plasticizer accounts for 5-10% of the total weight. If the content of lactone plasticizer is in the above range, it is preferable because the degree of curing is not impaired. If the content of lactone plasticizer is less than 5%, screen printing properties may be inhibited and the viscosity may be increased. When the content of lactone plasticizer exceeds 10%, the degree of curing decreases and heat resistance tends to deteriorate.

The adhesive paste composition of the present invention is characterized by adjusting the ratio between the epoxy resin and the inorganic filler, the epoxy resin and the lactone plasticizer in order to further improve the screen printing properties. The weight ratio of the epoxy resin and the inorganic filler is in the range of epoxy: inorganic filler = 1: 2 to 1: 7 to allow screen printing to adjust the viscosity of the composition. If the epoxy resin is less than 1/7 of the weight of the inorganic filler, the degree of curing and adhesion of the composition is poor. On the contrary, when the amount of the epoxy resin exceeds half of the weight of the inorganic filler, the reliability becomes poor.

In addition, the weight ratio of the epoxy resin and the lactone plasticizer is adjusted to be in the range of epoxy: plasticizer = 1: 1 to 5: 1, in order to control the viscosity, screen printing properties, and degree of curing of the composition. If the lactone plasticizer is less than 1/5 of the epoxy resin weight, the viscosity of the composition is increased. On the contrary, when the amount of lactone plasticizer is larger than that of the epoxy resin, the degree of curing decreases.

Rubber in the composition of the present invention serves to adjust the viscosity and hardness of the paste composition. The rubber may be a solid or liquid. Suitable rubbers for the compositions of the present invention include liquid polybutadiene, acrylonitrile-butadiene rubber, glycidyl acrylate, styrene-butadiene rubber, epoxy terminated butadiene-acrylonitrile (ETBN) rubber, carboxy terminated butadiene-acrylonitrile ( CTBN) rubber etc. are mentioned. As a rubber component which can be used for this invention, that whose weight average molecular weight is 3,000 or more is suitable. When the molecular weight of the rubber is less than 3,000, it is not preferable because of the poor reliability and processability. As for the molecular weight of rubber, it is more preferable that a weight average molecular weight is 50,000 or more. Rubber in the composition is preferably included in an amount of 5 to 15% by weight. When the content of the rubber component is less than 5% by weight, the toughness is not preferable, and when the content of the rubber component exceeds 15% by weight, the softening point is lowered, which is not preferable.

It is preferable to use the said hardening | curing agent either one or a combination of a phenolic or acid anhydride type, and an amine type hardening | curing agent. The curing agent is preferably included in an amount of 5 to 20% by weight in the composition. The content of the curing agent may vary depending on the type of curing agent, and the lower and upper limit settings indicate a general range of content that can effectively increase the crosslinking density when the curing agents described above cause a curing reaction with epoxy. The content of the curing agent component is less than the lower limit, the curing rate is not preferable, and if the upper limit is exceeded, the softening point decrease due to the heat resistance and the degree of curing decrease may be undesirable.

The adhesive paste composition for manufacturing a semiconductor device according to the present invention described above may further include a curing accelerator, a coupling agent, a leveling agent, a coloring agent, and the like.

The semiconductor packaging using the adhesive paste composition for a semiconductor package has an advantageous effect of obtaining high adhesion and reliability even if B-staging is omitted. For example, it provides durability and sufficient adhesion not to be damaged in the subsequent epoxy molding compound (EMC) process, for which the adhesion with the semiconductor when the screen printing is more than 100g / cm 2.

Although not wishing to be bound by any particular theory, it is believed that the adhesive paste composition of the present invention exhibits high adhesion even when B-staging is omitted unlike the prior art because of the following points. That is, in the adhesive paste composition of the present invention, the viscosity control is made of a plasticizer of less than 10% without a solvent, and the butadiene rubber having a molecular weight of 50,000 or more gives an adhesive force.

The semiconductor packaging process that proceeds using the adhesive composition for semiconductor packages provided by the present invention is well known in the art, and only an outline thereof will be briefly described below.

screen Printing  step( S1 )

The adhesive paste composition of this invention is apply | coated to the to-be-adhered member, for example, a PCB board | substrate, a lead frame, etc. using a stencil mask etc. at 0.2 cm / sec speed.

die  Gluing step ( S2 )

The die is attached to an upper surface of the die adhesive on which the screen printing process is completed.

wire Bonding  step( S3 )

Wire bonding between the bonded die and the member to be bonded is performed.

Sealing step ( S4 )

The outside of the result of the wire bonding is completed is sealed. This sealing is the most common epoxy molding compounding (EMC) process, and if the above-described process conditions and physical properties required for the die adhesive are met, a separate thermal curing process is performed to improve the heat resistance of the molding material and the die adhesive. It can meet the required physical properties without proceeding.

Performance is evaluated on the product produced via the above-described steps. For example, in the case of moisture resistance reliability, it is possible to evaluate whether the level 2 or higher reliability is shown in the Moisture Resistance Test (MRT) under Pb free proposed by the Joint Electron Device Engineering Council (JEDEC). have.

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 adhesive pastes of the present invention is determined by In order to determine the effect, the compositions of Examples 1 to 4 according to the present invention were prepared as in Table 1 below and compared with Comparative Examples 1 to 2 compositions. Each of the compositions of Comparative Examples 1 to 2 has the same components as the example compositions, but the content range of one or some of the components is out of the range defined in the claims below. In bold italicized in Table 1).

Furtherance
(weight%) Example number Comparative example number One 2 3 4 One 2 Epoxy Resin (X) 20 20 20 20 20 20 Inorganic Filler (Y) 58 58 44 44 25 44 Lactone plasticizer (Z) 10 13 10 13 13 30 Epoxy: Filler (X: Y) 1: 2.9 1: 2.9 1: 2.2 1: 2.2 1: 1.25 1: 2.2 Epoxy: Plasticizer (X: Z) 2: 1 1.5: 1 2: 1 1.5: 1 1.5: 1 0.67: 1 Rubber 10 10 10 10 10 10 Hardener 10 10 10 10 10 10 Other additives 5 5 5 5 5 5

[Explanation of Table 1]

The epoxy resin of the adhesive modifier used in the present invention had a liquid: solid epoxy ratio of 60:40 by weight. As the liquid epoxy, bisphenol A-based and bisphenol F-based epoxy resins were mixed in a ratio of 1: 1, and a solid epoxy was used as a bisphenol A-based epoxy resin. Hydrophobic surface-treated silica having a size of 1 μm or less was used as the inorganic filler, and butyrolactone was used as the lactone. As the rubber, butadiene-acrylonitrile-based (CTBN) rubber having a carboxyl group having a molecular weight of 50,000 as a terminal was used. The curing agent used a phenol curing agent and an amine curing accelerator. As other additives, coupling agents, coloring agents, and the like were used.

Example  One

Liquid adhesive composition having a component content of 20 g of epoxy resin, 10 g of organic filler (acrylonitrile based carboxyl group) rubber, inorganic filler 58 g, curing agent 10 g, curing accelerator 0.5 g, plasticizer 10 g, coupling agent 2 g, colorant 3 g Was prepared. The adhesive paste composition thus prepared was screen printed on a PCB substrate using a stencil. Thereafter, a silicon chip (die) having a size of 11.0 mm × 11.0 mm is bonded onto the paste. At this time, the adhesion was carried out under a load of 3 to 7 kg for 0.2 to 2.0 seconds at a temperature of 100 to 130 ℃. Then, the results of evaluating the adhesion and die adhesion characteristics are shown in Table 2 below.

Example  2 ~ Comparative example  One

Prepared as in Example 1, but in the case of Comparative Examples only the composition of the inorganic filler and the plasticizer was different.

Physical properties of various items as shown in Table 2 were evaluated for the result of screen printing according to the above Examples and Comparative Examples. Each test in Table 2 was made as follows.

Printing  characteristic

The sample which adhered the die by the optical microscope was evaluated. After printing, evaluation items of bleeding out, tailing, and clogging were observed. It was determined that the bleeding out when the paste resin oozed out to each printed surface, the tail was stretched when the screen was printed, and when the paste was printed like a tail on the back, the tailing was formed and the clogging occurred when the paste was printed in the crater shape.

Chip Attachment Characteristics

After attaching the chip and glass, it was evaluated visually. It was judged that the adhesive liquid did not stick out around the chip | tip, and it was favorable that the void after glass adhesion was 10% or less of the total area.

Cracking Characteristics after Curing

The chip and glass were attached and then thermally cured and evaluated by an optical microscope. It was judged that the adhesive liquid did not stick out around the chip | tip, and it was favorable that the space | gap after glass adhesion was 10% or less of the total area.

division Example number Comparative example number One 2 3 4 One 2  Viscosity (cPs) 60,000 60,000 60,000 60,000 60,000 60,000  Screen printing characteristic Good Good Good Good Good Good  Chip Attachment Characteristics Good Good Good Good Bad Good  Crack after curing Good Good Good Good Good fracture

As can be seen through Table 2, in the case of the embodiment of the present invention it can be seen that the screen printing characteristics, chip adhesion characteristics and stability after curing is very strong. On the contrary, in Comparative Examples 1 and 2, it is confirmed that the die adhesion characteristics are not good because the amount of void generation is relatively large.

As described above, an embodiment according to the present invention has been disclosed. 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 (8)

10-25 wt% epoxy resin; 40-70% by weight of inorganic fillers; Rubber 5-15 wt%; 5-20% by weight of curing agent; And 5 to 7% by weight of 5 to 7-membered ring lactone plasticizer which causes a ring opening reaction at a temperature of 100 ℃ ~ 150 ℃, The weight ratio of the epoxy resin and the inorganic filler is epoxy resin: inorganic filler = 1: 2 to 1: 7, The weight ratio of the plasticizer and the epoxy resin is an epoxy resin: plasticizer = 1: 1 to 5: 1 adhesive paste composition for manufacturing a semiconductor device. The method of claim 1, The lactone plasticizer is selected from the group consisting of γ-nonalactone, γ-undecalactone, glucono-α-lactone, γ-butyrolactone, and mixtures thereof. The method of claim 1, The epoxy resin is a single paste or a mixture of two or more selected from bisphenol A, bisphenol F. cresol novolac and phenoxy epoxide epoxy adhesive composition for manufacturing a semiconductor device. The adhesive paste composition for manufacturing a semiconductor device according to claim 3, wherein the epoxy is a solid-liquid mixed liquid of solid phase: liquid phase = 1: 9 to 4: 6. The adhesive paste composition of claim 1, wherein the inorganic filler is selected from the group consisting of silica, antimony oxide, aluminum oxide, magnesium oxide, titanium oxide, silver powder, copper powder, and mixtures thereof. The method of claim 1, The rubber is selected from liquid polybutadiene, acrylonitrile-butadiene rubber, glycidyl acrylate, styrene-butadiene rubber, epoxy terminated butadiene-acrylonitrile (ETBN) rubber and carboxy terminated butadiene-acrylonitrile (CTBN) rubber. Adhesive paste composition for manufacturing a semiconductor device, characterized in that one single or a mixture of two or more. The adhesive paste composition of claim 1, wherein the curing agent is selected from phenolic, acid anhydride, amine based curing agents, and mixtures thereof. The method according to any one of claims 1 to 7, The adhesive paste composition for manufacturing a semiconductor device, the adhesive paste composition for manufacturing a semiconductor device, characterized in that the adhesive force with the semiconductor when the screen printing without the B-staging step is 100g / cm 2 or more.