Adhesive for joining metals and resins, its adhesive layer and application thereof

Abstract

An adhesive for joining metals and resins is disclosed. The adhesive comprises 0.0001˜3 wt. % of amino silane, 0.0001˜1 wt. % of a crosslinker and 0.0001˜3 wt. % of an organometallic compound. In particular, the adhesive forms an adhesive layer that has a metal atomic ratio less than 50%.

Claims

1. An adhesive for joining metals and resins, comprising, 0.0001-3 weight percent of amino silane, wherein the amino silane is a compound shown as formula (1),
(NH.sub.2—R.sub.1)—Si—(O—R.sub.2).sub.3  (1) where R.sub.1 is a C1˜C10 alkyl group or a C1˜C10 alkyl group containing amino group, and R.sub.2 is a C1˜C3 alkyl group; 0.0001-1 weight percent of a crosslinker, wherein the crosslinker has a formula (2),
Si—(O—R.sub.3).sub.4  (2) where R.sub.3 is C1˜C10 alkyl groups or C1˜C10 alkyl groups with additional function groups selected from the group consisting of amino group, hydroxyl group, carbonyl group, aromatic group, siloxane group and their combinations; and 0.0001-1 weight percent of an organometallic compound, wherein the organometallic compound adheres to either formula (4)
M-(OR.sub.a).sub.4  (4) where M is Ti or Zr and R.sub.4 is a linear C.sub.1-C.sub.5 alkyl group or branched C.sub.1 to C.sub.5 alkyl group; or formula (5)
M-(OR.sub.a).sub.3  (5) where M is Al or Y and R.sub.4 is defined as above.

2. The adhesive of claim 1, further comprises 0.0005-95 weight percent of water.

3. The adhesive of claim 1, further comprises 0.0005-95 weight percent of solvents.

4. An adhesive layer, being formed by the adhesive of claim 1, and the adhesive layer comprises peaks at 660˜690 cm.sup.−1, 90˜1100 cm.sup.−1, 1100˜1380 cm.sup.−1, 1400˜1500 cm.sup.−1 and 3200˜3400 cm.sup.−1 in a FTIR spectrum.

5. The adhesive layer of claim 4, being a part of an article selected from the group consisting of a semiconductor, a circuit board, a liquid crystal board, and a light emitting diode.

6. A method for preventing metals from oxidation, comprising, using the adhesive of claim 1 to form a film on surfaces of a metal for preventing the metal from oxidation, wherein the film is to join the metal to a resin, wherein the resin comprises polyimide, epoxy resin, polyacrylate, polybenzoxazole, polybenzocylobutene or their combinations.

7. The method of claim 6, wherein the metal comprises Cu, Al, Ti, Ni, Sn, Fe, Ag, Au, Zr or an alloy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is FTIR spectrum of adhesive layer formed by composition D;

(2) FIG. 2 is TEM EDX Line spectrum of adhesive layer formed by composition D;

(3) FIG. 3 is TEM EDX Line spectrum of adhesive layer formed by composition E;

(4) FIG. 4 is DSC spectrum of adhesive layer formed by composition D;

(5) FIG. 5 is images of oxidation testing of Cu/Si substrate; and

(6) FIG. 6 is images of thermal stability testing of the adhesive layer.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) In a first embodiment, the invention discloses an adhesive for joining metals and resins. The adhesive for joining metals and resins comprises 0.0001-3 weight percent of amino silane, 0.0001-1 weight percent of a crosslinker and 0.0001-1 weight percent an organometallic compound, and the weight percent is calculated based on total weight of the adhesive.

(8) In one example of the first embodiment, the adhesive for joining metals and resins comprises 0.5-1 weight percent of the amino silane, 0.1-0.5 weight percent of the crosslinker and 0.2-0.5 weight percent of the organometallic compound.

(9) In one example of the first embodiment, the adhesive for joining metals and resins further comprises 0.0005-95 weight percent of water. Preferably, the adhesive for joining metals and resins further comprises 10-50 weight percent of water.

(10) In one example of the first embodiment, the adhesive for joining metals and resins further comprises 0.0005-95 weight percent of solvents. Preferably, the adhesive for joining metals and resins further comprises 50-90 weight percent of solvents.

(11) The solvents comprise protic solvents or aprotic solvents. Preferably, the solvents comprise alcohol, ether, ketone, N-methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO), 1,3-dimethyl-2-imidazoline or their mixture.

(12) In one example of the first embodiment, the amino silane is a compound shown as formula (1), and R.sub.1 is a C1˜C10 alkyl group or a C1˜10 alkyl group containing amino group; and R.sub.2 is a C1˜C3 alkyl group.
(NH.sub.2—R.sub.1)—Si—(O—R.sub.2).sub.3  (1)

(13) In one preferable example, the amino silane comprises (3-aminopropyl)trimethoxysilane, N-[3-(trimethoxysilyl)propyl]ethylenediamine, N-(3-trimethoxysilylpropyl)diethylenetriamine, 1-[3-(trimethoxysilyl)propyl]urea, trimethoxy[3-(methylamino)propyl]silane, (N,N-dimethylaminopropyl)trimethoxysilane, N-(3-triethoxysilylpropyl)diethanolamine, triethoxy-3-(2-imidazolin-1-yl)propylsilane, trimethoxylsilylpropyl modified (polyethylene)imine or their combinations.

(14) In one example of the first embodiment, the crosslinker has a formula (2), and R.sub.3 is C1˜C10 alkyl groups or C1-C10 alkyl groups with additional function groups selected from the group consisting of amino group, hydroxyl group, carbonyl group, aromatic group, siloxane group and their combinations.
Si—(O—R.sub.3).sub.4  (2)

(15) In one preferable example, the crosslinker comprises tetraethoxysilane, bis[3-(trimethoxysilyl)propyl]amine, N,N′-bis[(3-trimethoxysilyl)propyl]ethylenediamine, N,N′-bis(2-hydroxyethyl)-N,N′-bis(trimethoxysilylpropyl)ethylenediamine or a compound has a formula (3).

(16) ##STR00001##

(17) In one example of the first embodiment, the organometallic compound has a formula of (4) where M is Ti or Zr or a formula (5) where M

(18) is Al or Y; R.sub.a is straight C1-C5 alkyl group or branched C1-C5 alkyl group.
M-(OR.sub.4).sub.4  (4)
M-(OR.sub.4).sub.3  (5)

(19) In one example of the first embodiment, the adhesive forms a thermal stable adhesive layer or a redistribution layer. The thermal stable adhesive layer or redistribution layer has a metal atomic ratio less than 50%.

(20) In a second embodiment, the invention provides an adhesive layer. The adhesive layer is formed by the adhesive of the first embodiment, and has a metal atomic ratio less than 50%.

(21) In one example of the second embodiment, the metal atomic ratio is Cu atomic ratio, Al atomic ratio, Ti atomic ratio, Zr atomic ratio or Y atomic ratio.

(22) In one example of the second embodiment, the adhesive layer is a part of a semiconductor, a circuit board, a liquid crystal board or a light emitting diode.

(23) In one example of the second embodiment, the adhesive layer comprising characteristic peaks at 660˜690 cm.sup.−1, 900˜1100 cm.sup.−1, 1100˜1380 cm.sup.−1, 1400˜1500 cm.sup.−1 and 3200˜3400 cm.sup.−1 in a FTIR spectrum.

(24) Additionally characteristic peaks at 1550˜1650 cm.sup.−1 and 2800˜3000 cm.sup.−1 are also included in the FTIR spectrum.

(25) The characteristic peaks at 900˜1200 cm.sup.−1 prove the adhesive layer has 3-dimensional (3D) networks structure construct by bonding of Si, O and metals (950˜980 cm.sup.−1; Si—O-M) and siloxane bond (1000˜1165 cm.sup.−1; Si—O—Si).

(26) The adhesive layer has the 3-dimensional (3D) networks structure which formed by crosslinking bond with Si—O-M and Si—O—Si. In general, the chemical structure is shown as formula (5).

(27) ##STR00002##

(28) M is Al, Ti, Zr or Y. O is oxygen. A, B, C and D represent Si—O-M bond formed by the crosslinker Si—(O—R.sub.3).sub.4 and organometallic compound M-(OR.sub.4).sub.4 or Si—O—Si bond formed by condensation of the crosslinker and organometallic compound, respectively.

(29) In a third embodiment, the invention discloses a method for preventing metals from oxidation. The method comprises a step of using the adhesive of the first embodiment to form a film on surfaces of a metal for preventing the metal from oxidation.

(30) In one example of the third embodiment, the metal comprises Cu, Al, Ti, Ni, Sn, Fe, Ag, Au, Zr or an alloy. Preferably, the alloy is composed of one selected from the group consisting of Cu, Al, Ti, Ni, Sn, Fe, Ag, Au, Zr and their combinations.

(31) In one example of the third embodiment, the film is to join the metal to a resin. The resin comprises polyimide, epoxy resin, polyacrylate, polybenzoxazole, polybenzocylobutene or their combinations.

(32) In one example of the third embodiment, the method use in a redistribution layer process

(33) Working examples of the invention are described as following paragraphs.

Example: General Procedure for Preparing the Adhesive Layer

(34) The adhesive layer forms by dip-coating or spray-coating the invented adhesive composition on testing samples at ambient temperature or elevated temperature. Processing time varies from 1.5˜5 minutes, depending on the desired thickness of the adhesive layer. After coating process is finished, the remaining residual solvents can be rinsed off by water or spun off by high rotation speed, following by nitrogen or air blow process to facilitate the drying process.

(35) According to the general procedure, some representative adhesive layers are prepared and list in Table 1. Composition A and H are control groups without adding organometallic compounds, respectively. Composition B is a control group without adding the crosslinker.

(36) N-(3-Trimethoxysilylpropyl)diethylenetriamine has following structure (6)

(37) ##STR00003##

(38) N-[3-(Trimethoxysilyl)propyl]ethylenediamine has following structure (7)

(39) ##STR00004##

(40) N,N-Bis[3-(trimethoxysilyl)propyl]amine has following structure (8)

(41) ##STR00005##

(42) TABLE-US-00001 TABLE 1 Composition Amino-silane Crosslinker Organometallic compound Solvent H2O A 1 wt.% 0.2 wt. % 0 78.8 wt. % 20 wt. % N-(3- N,N-Bis[3- Trimethoxysilylpropyl)diethlyene triamine (trimethoxysilyl)propyl]amine B 1 wt.% 0 0.2 wt. % M(OR.sub.4).sub.4 78.8 wt. % 20 wt. % N-(3- (M = Al) Trimethoxysilylpropyl)diethylene triamine (R.sub.4 = tri-sec butyl) C 1 wt.% 0.2 wt. % 0.2 wt. % M(OR.sub.4).sub.4 78.6 wt. % 20 wt. % N-(3- N,N-Bis[3- (M = Al) Trimethoxysilylpropyl)diethylene triamine (trimethoxysilyl)propyl]amine (R.sub.4 = tri-sec butyl) D 1 wt.% 0.2 wt. % 0.2 wt. % M(OR.sub.4).sub.4 78.6 wt. % 20 wt. % N-(3- N,N-Bis[3- (M = Zr) Trimethoxysilylpropyl)diethylene triamine (trimethoxysilyl)propyl]amine (R.sub.4 = butyl) E 1 wt.% 0.2 wt. % 0.5 wt. % M(OR.sub.4).sub.4 78.3 wt. % 20 wt. % N-[3- N,N-Bis[3- (M = Al) (Trimethoxysilyl)propyl]ethylenediamine (trimethoxysilyl)propyl]amine (R.sub.4 = tri-sec butyl) F 1 wt.% 0.2 wt. % 0.5 wt. % M(OR.sub.4).sub.4 78.3 wt. % 20 wt. % N-[3- N,N-Bis[3- (M = Ti) (Trimethoxysilyl)propyl]ethylenediamine (trimethoxysilyl)propyl]amine (R.sub.4 = isopropyl) G 1 wt.% 0.2 wt. % 0.5 wt. % M(OR.sub.4).sub.4 78.3 wt. % 20 wt. % N-[3- N,N-Bis[3- (M = Zr) (Trimethoxysilyl)propyl]ethylenediamine (trimethoxysilyl)propyl]amine (R.sub.4 = ethyl) H 1 wt.% 0.2 wt. % 0 78.8 wt. % 20 wt. % N-[3- N,N-Bis[3- (Trimethoxysilyl)propyl]ethylenediamine (trimethoxysilyl)propyl]amine

(43) Analysis of Chemical Structure and Bonding of the Adhesive Layer

(44) Use Fourier Transform Infrared Spectroscopy (FTIR) to analyze chemical structure and bonding of the adhesive layer. The FTIR spectrum of the adhesive layer typically comprises following characteristic peaks. 660˜690 cm.sup.−1 (—Si—O—Si bending), 900˜1100 cm.sup.−1 (mixed network of Si—O-M (950-980 cm.sup.−1) and Si—O—Si (1000˜1165 cm.sup.−1), 1100˜1380 cm.sup.−1 (Si—C, —C—N, —C—C—, C—H in Si—CH2), 1400˜1500 cm.sup.−1 (CH in Si—CH2), 1550˜1650 cm.sup.−1 (—NH), 2800˜3000 cm.sup.−1 (—CH.sub.2) and 3200˜3400 cm.sup.−1 (—OH, —NH stretch).

(45) Analysis of Cross Section of the Adhesive Layer

(46) Use Transmission Electron Microscope (TEM) to analyze cross section of the adhesive layer. TEM analysis indicate the adhesive layer formed by composition D has a Zr atomic ration about 5% as shown in FIG. 2; and the adhesive layer formed by composition H has a Al atomic ration about 30˜40% as shown in FIG. 3.

(47) Analysis of Thermal Properties of the Adhesive Layer

(48) Use DSC to analyze thermal stability of the adhesive layer. As shown in FIG. 4, DSC analysis indicates the adhesive layer formed by composition D does not observe exothermic reaction at 25˜350° C., and that means the structure of the adhesive layer formed by composition D is thermal stable.

(49) Oxidation Testing of Metal Substrates

(50) The testing substrate is Cu/Si. Composition A, B, C and D formed a film on surface of the Cu/Si substrate for the oxidation testing, respectively. Control group is Cu/Si substrate without coating any composition. Testing condition is to put samples on a hot plate and heat in air at 150° C. and 190° C. for 10 minutes, respectively. Oxidation level 1 represents no oxidation of Cu is observed. Oxidation level 2 means when Cu is oxidized to CuO.sub.2 and the Cu/Si substrate color becomes orange. Oxidation level 3 means when Cu is further oxidized to CuO and the Cu/Si substrate color becomes brown. Oxidation level 4 means when Cu is final oxidized to CuCO3 or CuSO4 and the Cu/Si substrate color becomes green. According to Table 2 AND FIG. 5, the film formed by the adhesive composition A and B are not able to prevent Cu/Si substrate from oxidation. On the contrary, the Cu/Si substrate coated with the film formed by the invented adhesive composition C and D does not become orange color, as a result, the film formed by the invented adhesive composition C and D prevent Cu/Si substrate from oxidation.

(51) TABLE-US-00002 TABLE 2 Coating Composition Oxidation level 150° C. (10 min) 190° C. (10 min) Control group 3 4 A 2 3 B 1 2 C 1 1 D 1 1

(52) Thermal Stability Testing of the Adhesive Layer

(53) The coating compositions C, D, E, F, G and H list in Table 1 is cured at 230° C. for 2 hours for obtaining adhesive layers, respectively.

(54) The thermal stability testing is to place the adhesive layers in an oven, heat the adhesive layers to 260° C. at first, keep them at 260° C. for 1 minute, and then cool the adhesive layers to room temperature. Repeat the aforementioned heating-cooling process 20 times and then analyze the adhesive layer properties. The thermal stability testing results are list in Table 3 and shown in FIG. 6.

(55) TABLE-US-00003 TABLE 3 Coating Composition Oxidation level(nm) Void level (%) Morphology C 130 50 twisted D 130 1 normal E 130 80 normal F 130 90 twisted G 130 30 normal H 130 95 normal

(56) Evaluation of oxidation level is to measure thickness of the formation of CuO. The thickness of the formation of CuO increases due to oxidation of the Cu bump. Void level represents the pore percent appear in the adhesive layers. More pores appear in the adhesive layers means structure of the adhesive layers is unstable and not able to suffer from oxidation. Morphology represents the appearance of the Cu bump. Twisted appearance represents the adhesive layers are not able to resist the thermal stress relaxation generated by the thermal expansion of Cu bump and the resins

(57) Obviously many modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the present invention can be practiced otherwise than as specifically described herein. Although specific embodiments have been illustrated and described herein, it is obvious to those skilled in the art that many modifications of the present invention may be made without departing from what is intended to be limited solely by the appended claims.