TW200927789A - Prepolymer and thermosetting resin composition made therefrom - Google Patents

Abstract

This invention discloses a prepolymer obtained by utilizing 4-(N-maleic benzimide) phenylglycidyl ether epoxy (MPGE) and 4,4'-diamine diphenylmethane bimaleic imide (BMI) as reactants, initiating the reaction with free radical initiator in a solvent, and adding polymerizing inhibitor after reacting. The mole ratio of BMI and MPGE is 0.05 to 0.5. The amount of initiator is 0.01% to 0.15% of the total molar amounts of the monomer reactants. The amount of solvent is 50% to 70% of the total weight of the reactants. The amount of polymerizing inhibitor is a half to one time amount of the initiator to be used. The prepolymer may be used to manufacture high performance thermosetting resin composition corresponding to the requirement of electronic elements and integrated circuit (IC) packaging.

Description

。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 [Prior Art] The demand for electronic information products in terms of thinness, lightness, and high density has driven the development of printed circuit boards toward thin-line and micro-hole technology. Coupled with the continuous advancement of miniaturized surface mount technology, the demand for high-end 1C package substrates continues to increase. Q The traditional IC package uses a lead frame as the carrier for the 1C conduction line and the supporting IC. It is connected to the pins on both sides or around the lead frame. With the development of 1 (: packaging technology, the number of pins increased (more than 300 pins), the increase in wiring density, the number of substrate layers increased, making QF? (Quad Flat Package 'small squares Packages such as planar package) are limited in their development. In the mid-1990s, a new type of IC package represented by BGA (Ball Grid Array package) and CSP (Clip Scale Package) The form came out, and it also produced a necessary new carrier for semiconductor chip packaging. This is the ic package substrate (IC Package Substrate, also known as the c package carrier). In recent years, 'BGA (Ball Grid Array Package), CSP (The chip-level package) and the FC (FI ip Chip, 】 曰曰 soldering sheet) and other forms of ic package substrate have rapidly expanded in the field of application and are widely popular. The world's major manufacturing countries and regions engaged in packaging manufacturing are The packaging substrate market is experiencing fierce competition. This competition focus is mainly on the use of high-density multilayer substrate technology in the 1C package and the reduction of package substrates. In terms of manufacturing cost, the development of a substrate material for a 1C package carrier (also referred to as an IC package substrate) is a very important issue at present. With the development of high frequency and low power consumption in 1C packages, Ic package substrates are low. Important properties such as dielectric constant, low dielectric loss factor, and high thermal conductivity will be improved. An important direction of JC package carrier research and development is the effective thermal and thermal integration of the thermal connection technology of the substrate. The power consumption of the device generates a large amount of heat, which causes the device temperature to rise to the south. Generally speaking, for every 18 degrees of temperature increase, the possibility of device failure increases by 2 to 3 times. As a result of 5 200927789, the thermal conductivity of the package material is improved. It is especially important to solve the heat dissipation problem to ensure that the circuit works normally within the operating temperature range. The ic package carrier board also needs to solve the problem of inconsistency with the thermal expansion coefficient of the semiconductor wafer. Even the laminated multi-layer board suitable for micro-circuit fabrication There is an insulating substrate in the thermal expansion system. The number of the surface is large (the fine-grained, the number is 6 () ppm / °c) paste. The number reaches the 6_纟 right close to the semiconductor wafer, and it is indeed a “silver challenge” for the manufacturing technology of the substrate. 1C package design, manufacturing technology development, the substrate material that is shot is corrected to more stringent requirements. It is manifested in the following aspects: high and high thermal compatibility corresponding to 无 and error-free flux; 2) low dielectric loss factor characteristic of loss of power loss; 3) low dielectric constant corresponding to high speed; 4) Low temperament (improvement of flatness of the surface of the substrate); 5) low moisture absorption rate, Europe, 6) low thermal expansion coefficient, so that the coefficient of thermal expansion is close to 6 qing; 疋) low formation of the package carrier: nature; 8) Low-cost built-in components; 9) High-strength performance at high temperatures; 1)) Environmentally-friendly substrate materials that are low-cost and suitable for lead-free reflow soldering processes. The portion of the substrate to be touched by the 1C package is composed of an organic resin. A number of resins have been used in the field, such as epoxy resin, acetaminophen resin, cyanate resin, and bismaleimide-triazine resin (BT). 〇% Oxygen is the best way to make it. It is easy to process and has good dryness to all kinds of substrates. 胄Wei Xue and Hybridity, Excellent Lai Noodle. However, the remuneration of epoxy resin at the temperature of 胄 《 人 人 人 人 人 人 《 常 ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( They are 4.85 and 4.53 respectively) and have a high water absorption rate. Epoxy resins are usually cured with amines and acid needles, and the solidified material inevitably contains a hydrophilic group such as a decrease in the amount of phase tA, resulting in a large water absorption rate of the material. Therefore, under high temperature and high humidity conditions, the cured epoxy resin is very sensitive to water. ^ Yu Chuan (4) Epoxy resin, _s_ can have a certain degree of improvement. In order to achieve high crosslink density and high glass transition temperature (Tg) and low dielectric properties, cyanide __ is usually required. However, the grease itself is expensive and has a disadvantage of high brittleness and high water absorption after curing. The other major class of resin is Bismaleimide, which is characterized by excellent physical properties under high temperature and high humidity conditions and stable electrical properties over a wide temperature range. These characteristics make the double 2 to imine system suitable for the new composite material _ electronic appliances. Double-branched imine has good moist heat performance at temperatures up to 230-25 (TC temperature. However, Bismaleimine is not soluble in traditional organic sprays, because it is added to the scent. There are also shortcomings such as the curing conditions that are too harsh, and the disadvantages such as the 胃 般 容 胃 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下 下BT resin. This type of resin was first developed and patented by Witsubishi GasC., Ltd. (Mitsubishi Gas, Inc.) (US Patent US 411〇, 364). Double maleicin-triazine resin (abbreviated as Βτ resin) ) is a high-polymer resin obtained by copolymerization of yoghurt vinegar resin (10) with 〇 〇CN and bis-male yamine resin _) in 17 〇 Ca, and finally obtains a high-gas triazine ring. A polymer composed of a nitrogen heterocyclic structure such as an imine ring. The cured product of the BMI/CE copolymer has both impact resistance and electrical insulation (mainly in low ε, low tan(5) and process operability, and also improves the cyanate resin. The financial seat maintains the high heat resistance of both. 〇 Due to the substrate material made of BT resin, it is resistant to PCT (Pressure Cooker Test), metal ion mobility, heat resistance, The dielectric properties, heat and humidity resistance and high/impact impact are excellent. The side is the machine at high temperature (mainly including high temperature resistance (four degrees), hybrid mode 4, _ reduction intensity and surface Wei, etc.) It has more outstanding advantages than the substrate materials of other resins (such as the substrate, the pro-imine, and the substrate of the poly-brain). Therefore, the wafer mounting and the density cloth are improved in the application of the IC package substrate. Strong material and process plus, the substrate material of BT resin slaves accounts for a large proportion of the various substrate materials used in 1C packaging. Despite the 疋, BT resin has a high crosslink density after polymerization, plus molecular The structure of the middle three-ring ring is highly symmetrical, ... The cured product is brittle, and the cyanic acid vinegar resin ((8), which is expensive due to the synthesis process of its complex 7 200927789, increases the flexibility and processability and reduces the cost, and it becomes the Mitsubishi Gas in August 1978. The BT resin patents of the chemical company have been the focus of many patents. The patents in this area are as follows: US4456712, US4683276, US4749760, US4847154, US4902778, US4927932, US4996267, US6534179, US6774160, JP1197559, JP7070316, JP200129468, JP2006169317, JP2006022309 etc. In addition, epoxy resin / bismaleimide system, BT resin, etc. can not form a stable solution in various low boiling solvents. To facilitate impregnation, it is usually necessary to use a high boiling point strong polar solvent such as dimethyl. The ratio of the base amine (10)F) to the N-fluorenyl group. If the solution is finely assisted, the use of a solvent such as DMF and N-methylpyrrole ketone will accelerate the reactivity of the resin system and seriously affect the resin composition. The gel time brings certain problems to the gluing process. Direct use of 4-(N-maleimide benzene) ) Glycidyl ether (MPGE) epoxy resin is used as a curing agent with (7) or phenolic resin as a curing agent, and the glass transition temperature can only reach 17 〇. Around ,, to further increase the glass transition temperature, it is necessary to double the horse. In the case of simple blending, since the compatibility of the two is poor, phase separation occurs and is not suitable for the impregnation process, and prepolymerization treatment is required for this purpose. Conducted research to develop a prepolymer that can be used to manufacture high-Q-energy thermosetting resin compositions, and to use the prepolymer to produce high-performance thermosetting resins corresponding to electronic components and integrated circuit (1C) packaging requirements. The composition is low in cost and does not need to use a high boiling point polar solvent such as DMF and N-methyl calcined hydrazine, but is soluble in ordinary low-point non-polar solvents such as acetone, toluene, di-oxygen, butanone. Or a stable solution is formed in methyl isobutyl ketone, and the present invention is produced. SUMMARY OF THE INVENTION An object of the present invention is to provide a high heat resistant prepolymer which can be used to form a high performance thermosetting resin composition corresponding to the requirements of electronic components and integrated circuit (1C) packaging. A further object of the present invention is to provide an inexpensive, novel thermosetting resin composition produced by using the prepolymer, which forms a stable homogeneous solution in a low boiling point solvent, and is manufactured by the coating of 8 200927789 Copper plate material has high glass transition temperature (Tg), excellent dielectric properties, low expansion coefficient, low water absorption, high thermal shock resistance and excellent thermal conductivity. It is suitable for electronic components and integrated circuit (ic) packages. Substrate material. The invention provides a prepolymer comprising 4-(N-maleimide phenyl) glycidyl ether (MpGE) epoxy resin and 4,4-diaminobenzophenone-type bismaleimide. (BMI) is the reactant, the reaction is initiated by a free radical initiator in a solvent, and a polymerization inhibitor is added after the reaction, the molar ratio of Bmi to mpge is 0.05 to 0.5; the amount of the initiator is the reactant monomer The molar amount is 〇. 〇. 15%; the solvent is used in an amount of 50% to 70% by weight based on the total weight of the reactant; and the polymerization inhibitor is used in an amount of from half to one times the molar amount of the initiator used. The above solvent is one or more of acetone, toluene, dimethylacetone, methyl ethyl ketone or methyl isobutyl ketone, and cyclohexanone. The above initiator is an azo initiator, the reaction temperature is controlled at 6〇-9 (TC, and the reaction time is controlled at 10-60 min. The above initiator is a peroxide initiator, and the reaction temperature is controlled at l〇0_13 (rc, The reaction time is 10-60 min. The above polymerization inhibitor is an electron-donating substance such as an anthracene, an aromatic nitro compound or a volatile metal salt, or an electron-donating substance such as a phenol or an amine. The molar ratio of BMI to MPGE is better. 05%至〇·10。 More preferably the amount of the initiator is 0. 05% - 〇. 10%. More preferably used in an amount of 60% - 70% of the total weight of the reactants. The 5% by weight of the solids of the composition, wherein the weight of the solids of the composition is 1.90-34. 5%; (2) at least A styrene-maleic anhydride oligomer having a molecular weight in the range of from 1400 to 50,000, which comprises from 17.5% to 47.0% by weight of the solids of the composition; (3) at least one filler, based on 20% by weight of the solids of the composition %-60%; (4) at least one solvent, the solvent is added in an amount of from 2% to 50% by weight of the composition. (5) at least one can be used for coating Flame retardant for the board industry. The molecular weight of the styrene-maleic anhydride oligomer is preferably in the range of 1400 to 10000. The styrene-maleic anhydride oligomer is the best weight of the solids of the composition. The ratio is 22.50/〇-38. 0%. The filler is cerium oxide (including crystalline, molten and spherical cerium oxide), alumina, mica, talc, boron nitride, aluminum nitride. , a mixture of one or more of tantalum carbide, diamond, calcined clay 'alumina, aluminum nitride fiber or glass fiber. The filler accounts for an optimum ratio of the weight of the solids of the composition 3〇%-5〇% The solvent includes a mixture of one or more of acetone, mercaptoethyl ketone (butanone, MEK), methyl isobutyl ketone, cyclohexanone, toluene or dioxin. (1) 4-( N-maleimide phenyl)glycidyl ether (mpge) epoxy resin 〇maleimide can improve the high temperature resistance of epoxy resin. The modified route is useful for polybamazepine and epoxy. Resin reactive cross-linking to form an interpenetrating network (IPN); curing the epoxy resin with a curing agent containing a quinone imine group; using thermoplastic poly There are three kinds of quinone imine or polyimine functional groups and epoxy resin blending. The main disadvantage of these methods is that the compatibility of the quinone imine component and the epoxy resin is poor, and the processing and molding is difficult. The work of introducing an imine group into the epoxy resin backbone is a hot topic in the current research. It is usually added to the epoxy group by a polyimine or a quinone imine compound, or used as a curing agent to enhance the epoxy resin. Thermal stability and flame retardancy.

For the first time, Chuan-ShaoWu et al. used triphenylphosphine and methyl ethyl ketone as catalysts and solvents to carry out a simple addition reaction of q-hydroxyl-containing maleimine with an epoxy group to obtain an interpenetrating network structure. The glass transition temperature of the maleated imide modified epoxy resin was from 369. (: Increase to 381~386 °C, the residual carbon ratio of 800 °C in N2 atmosphere is up to 27.3%, L0I value is 29. 5. Ying-LingLiu et al. 4-(N-Malayya) Amine phenyl) glycidyl ether (MPGE) epoxy resin is obtained by curing DDM and DICY and DEP (diethyl phosphite) respectively. In a helium atmosphere, the 5% weight loss temperature can reach 355 ° C, completely The decomposition temperature (IPDT) reached 2287 ° C, the residual carbon rate at 800 ° C reached 60. 38%; in the air ' 5% weight loss temperature reached 348 ° C, the complete decomposition temperature reached 669 ° C, 80 (TC residual rate reached 11. 01%, L0I value up to 48.0. (2) 4, 4'-diaminodibenzofluorene type bismaleimide (BMI) 4,4'-diaminodiphenylmethane type double Malay Bismuthimide (BMI) is a polyaddition of polyimine. 200927789 Red is 4'4 _ recorded - benzene and diamine is heated or added to support the heteropolymer resin, it is in thermal polymerization After forming a polymer with a high degree of crosslinking, Α 0 has good heat resistance, flame resistance and insulation, and is moderately priced. Therefore, it is generally considered to be an ideal resin matrix for heat-resistant structural materials and insulating materials. = species with double official 'Use of organic compounds. The high affinity of the double bond makes it easy." A variety of nucleophile reactions, due to the structure of its five-membered heterocyclic ring, determines the unique heat resistance. (3) Free radical initiator in the initiator Under the action of heat, the mixture of 'legs and sputum' has a three-sided reaction: their respective homopolymerization and copolymerization between Lan 1 and MPGE. Therefore, the reactant ratio, the type and amount of the initiator, the type of solvent and The dosage, reaction temperature, reaction time, etc. are important factors influencing the reaction. Reactant ratio: the molar ratio of suitable to MPGE can be from 0.05 to 0 5, and the better ratio is 0.25-0.475. Type and amount: The appropriate initiator surface should be selected according to the needs, so that the rate of radical formation and the rate of polymerization are shot. If the activation energy of the initiator is too high or the half-life is too long, the branching rate is too low, which will prolong the polymerization time; If the activation energy is too low and the half-life is too short, it will be too fast, it is difficult to control the temperature, and it may cause explosion. It will prolong the polymerization time or premature decomposition of the initiator, and the cake will stop polymerization when the conversion is low. Gu An initiator of the order of magnitude or equivalent in the case of fading polymerization. Usually a composite initiator is chosen to allow the reaction to proceed at a more uniform rate. The commonly used initiators are azos (such as azobisisobutyronitrile) and peroxides. Classes (such as diisopropyl peroxide). The amount of initiator will affect the reaction rate and molecular weight. The amount of initiator is too low, the conversion of monomer is low; the amount is too large, the rate of free radical growth increases, which will cause the reactant system. The concentration of the transient free radicals is too concentrated, causing agglomeration. The appropriate initiator dose is 0.01%-〇. 15% (molar fraction) of the total amount of the monomer when the initial dose is 〇. 05% 〇. 10% (molar At the time of fractionation, the prepared prepolymer is dissolved in a common solvent such as acetone, butyl or the like to form a stable homogeneous solution. Reaction conditions, that is, control of reaction temperature and reaction time. If the reaction temperature is low, the reaction time required is long, and the reaction temperature south' reaction time can be shorter. However, the reaction temperature is very fast. 11 200927789 The reaction is too intense and may cause explosion. If an azo initiator such as azobisisobutyronitrile is selected, the reaction temperature should be controlled at 60-90 ° C, and the reaction time should be controlled at 10 _ 60 mir ^ If a peroxide initiator is selected, the reaction temperature should be increased to 100. —Uot. (4) Type and amount of solvent solvent used in prepolymerization: When a good solvent is used, it is homogeneous polymerization. If the amount of solvent is appropriate, the monomer concentration is not high, it is possible to eliminate the auto-acceleration effect, and select the precipitant. Or poor solvent, automatic acceleration is significant, and the reaction is not well controlled. One or more of acetone, toluene, dimethyl, butanone, cyclohexanone or methyl isobutyl ketone are usually used as a solvent. The solvent is preferably used in an amount of from 50% to 75% by weight based on the total weight of the entire reaction mixture, and the recommended amount of solvent is from 6% to 7% by weight. ^ (5) Inhibitors MPGE/BMI body green-discriminating ride pre-polymerization amp &, the side of the tree side in the storage process stability, also need to add an appropriate amount of inhibitor. Since the same polymerization inhibitor has different polymerization inhibitory effects on different monomers, a suitable polymerization inhibitor should be selected depending on the type of monomer used. The general selection principle is as follows: 1) For monomers having an electron-donating substituent, such as styrene, vinyl acetate, etc., an anthracene, an aromatic nitro compound or a volatile metal salt-based electrophilic substance may be used as a polymerization inhibitor; 2) For monomers with electron-withdrawing substituents, such as acrylonitrile, acrylic acid, decyl acrylate, etc., phenols, amines, etc. can be used as electron-inhibiting agents; 3) to avoid side reactions, avoid The inhibition polymerization agent and the initiator constitute an oxidation-reduction system to increase the reaction rate. In the present invention, an electron-donating substance such as an anthracene, an aromatic nitro compound or a variable-valent metal salt or an electron-donating substance such as a phenol or an amine is used. The amount of the polymerization inhibitor is preferably from half to one times (by moles) of the amount of the initiator to be used. (6) Styrene-maleic anhydride oligomer The thermosetting resin composition of the present invention comprises one or more styrene-maleic anhydride (SMA) oligomers. SMA can further improve the thermal and electrical properties of cured polymers and their articles. There are two main types of commercially available SMAs. One type is a high molecular weight copolymer (molecular weight of more than 100,000, or even up to a million). This type of SMA is actually a thermoplastic polymer and is not suitable for the manufacture of prepreg (PrepregS), in addition to its low anhydride content (generally in 5_15%), also 12 200927789 Does not work with the cross-linking agent of the cyclic resin. Another type of SMA, having a molecular weight of from 1400 to 50,000 and an anhydride content of greater than 15%, is contemplated by the present invention. The recommended molecular weight range for SMA oligomers is 1400-1000 (^ such as commercially available SMA1〇〇〇, SMA2〇〇〇, SMA3〇〇〇, SM4〇〇〇, styrene and maleic anhydride in these oligomers) The molar ratios are 1:1, 2:1, 3:1, 4:1, respectively, and the molecular weight ranges from 1400 to 2000. One or both of the above SMA copolymers are suitable for assembly to the present invention. The amount of SMA in the composition of the sapphire composition is from the weight percent of the solids of the composition, which is I.. 〇 by weight, the recommended amount is 22. 5-38. 0 parts by weight. Improve the chemical and electrical properties of the cured resin, such as lowering the coefficient of thermal expansion (CTE), increasing the modulus 'accelerating heat transfer, etc.. Dioxide (including crystalline, dazzling and spherical dioxide), oxygen, Mica, talcum powder, boron nitride, nitrogen, carbon solution, diamond, smoldering earth, oxygen, nitrogen, and __ materials can be added to the polymer-based composite packaging material. By selecting not thieves Different morphologies, such as difficult, spherical or ^-shaped inorganic substances' adjust their content, distribution and polymerization The combination of the interface can be used to weave the composite material within a certain range. The towel, calcined _ soil or silk dioxide, or the Wei-treated dioxin or yoke oxygen, etc. Preferred. ❹ The present invention relies on the total weight of the whole target compound of 2G_6 (10), the ratio of the material is 30% to 50% 〇... (8) The solvent used in the process of synthesizing the resin of the present invention In addition, you can use a variety of solvents to improve the solubility of the wax, and control the viscosity of the resin 'ensure that 1 spoonful of resin can be used. Suitable solvents include acetone, Yinji ethyl residue (butanone, legs) _ 'ring (10)n Dioxane or the like: or their second:: used _ continuation of viscera. If difficult === with Ming Gu agent, and if cured by infrared, it is usually necessary to use a mixture of toluene and _ 13 200927789 solvent. Solvent The amount is from 20% to 50% by weight of the whole composition. (9) Flame Retardant One or more flame retardants may be added to the resin composition of the present invention. Any flame retardant used in the copper clad laminate industry may be used in the present invention. Suitable flame retardants may include, but are not limited to, a halide of a glycidal squamous difunctional alcohol, a Novolac type resin tooth of bisphenol A, bisphenol f, polyvinyl phenol or phenol, cresol, phenol, etc., an inorganic flame retardant material such as antimony trioxide , red scale, bismuth oxide, partial rot, acid, magnesium hydroxide, scale flame retardant, such as tetraphenyl broken, tris (o-tolyl) diphenyl ester, triethyl phosphate, phosphoric acid a toluene diphenyl ester, an acid phosphate vinegar, a nitrogen-containing phosphate compound, a halogen-containing acid ester, etc. Another alternative flame retardant is a bromine-containing compound having the following structure: :

〇- u Br When using a compound containing a desert or a sulphur-containing epoxy resin or a desert-containing Novolac resin as a flame retardant, the amount is based on the total weight of the resin (four) body resin (four), and the optimum cerium content is 10 %-20%. The present invention can also purify the components as follows: (10) The rate at which the accelerator hardens. The accelerator selected may be a known accelerator at any rate. The suitable accelerator is imidazole, which can be used to identify the aging of a shirt and to speed up the resin. The temperature of the cake is buried in the mouth / mouth: 丨 _ _ know any can accelerate the hardening of the thermosetting resin, especially the base of the rice, such as 2-A 200927789 imidazole, 2-ethyl-4-methylimidazole, 2- Phenyl imidazole, 2-ethyl-4-phenylimidazole, and the like. Other suitable promoters include various quaternary amines such as benzyldimethylamine, 4,4,- and 3,3,-diaminodibenzoquinone. The recommended accelerator is 2-ethyl-4-methylimidazole. The amount of the accelerator to be used depends on the following factors: the type of the epoxy resin used, the type of the hardener, the type of the accelerator, and the like. The use of an excess of accelerator will result in an overly reactive resin system. The skilled artisan can readily determine the amount of promoter to provide sufficient activity for the resin to facilitate the impregnation of the prepreg. In general, the amount of the accelerator is between 0.001% and 2% of the total weight of the epoxy resin and the hardener. In most cases, the value range is 〇. 〇. 05%. The resin gelation time depends on the type and amount of the accelerator, the kind and amount of the solvent, the kind and amount of the filler, and the type of the prepreg to be produced (glass cloth type). (11) Toughener The resin composition of the present invention may include one or more toughening agents. The purpose of adding the toughening agent to the resin and σ is to improve the drilling properties and thermal reliability of the printed circuit board. Suitable augmentation agents include methyl methacrylate/butadiene/styrene copolymer, styrene/butadiene copolymer, t-methacrylic acid S曰/丁浠/本乙Core-shell particles, polydimethyl-based oxy-core shell particles, and the like, and mixtures thereof. The proposed toughening agent is MBS core-shell particles available from Rohm & Hass. The toughening agent is used in an amount of from 1% to 5% by weight based on the total solids of the composition, and the recommended amount is from 2% to 4%. ° (12) Other Additives The thermosetting resin composition of the present invention may further contain other additives such as an antifoaming agent, a leveling agent, a dye, a pigment, etc. In summary, the ratio of each component of the thermosetting resin composition of the present invention The scope is shown in Table 1. Table 1 Proportion of each component of thermosetting resin composition range 1C seal substrate resin composition formula (each component is based on solid content) Recommended dosage (Wt·%) 3Γ〇-2〇 component prepolymerization Scope of the material (Wt. %) 1.90-34.5 15 200927789 Styrene-maleimide copolymer toughener accelerator filler flame retardant SMA MBS core-shell particles imidazole filler 17. 5-47.0 1-5 0.001-2 20-60 Wood is suitable for the flame retardant of the CCL industry. Note: *Because it is not obstructed (4), the series makes 22.5-38. 0 2-4 〇. 001-0. 05 30-50 rafts, MPGE and The mixture is first dissolved in a solvent (the solvent is used in an amount of 50-70% by weight based on the weight of the entire reaction mixture), and reacted at a certain temperature for 10-6 under the action of an initiator (Μη, and then a polymerization inhibitor is added] 趁热秘1〇_ 15 min, cooling. The obtained prepolymer was added to a solvent previously dissolved in methyl ethyl ketone. , flame retardant, agent, accelerator, after fully mixing, slowly add people and other additives, and then add an appropriate amount of solvent, so that the amount of solids obtained in the final resin composition is 45_7Q%, The recommended amount of solution is to adjust the solids content of the composition to be 50-65%. The composition of the present invention is formed after full length. The prepreg is produced in a continuous process using the present invention. Glass fiber material as a button. Roll-shaped glass material _ ground through - _ roller into the glue tank 'slot is filled with this fine composition 4 on the glue tank 襄 _ fiber cloth is fully wetted by the resin, and then passed The metering roller scrapes off the excess resin and enters the gluing oven for baking for a certain period of time, so that the agent evaporates and the gHb-definitely cools and rewinds to form a prepreg. The electronic grade 7628 glass of the number of sheets will be fixed. The prepreg made of the fiber cloth immersed in the above resin is superimposed and aligned, and the upper and lower parts are respectively equipped with the electrolysis of the loz. In the vacuum display, the temperature is within 30 内, and the temperature is increased from 8 (rc to 2 〇 (rc). , then hot press at 2 〇〇t & and then cool to room temperature in 30 sides to make a A double-coated steel plate of a constant thickness. Generally, 5 sheets of 7628 prepreg are required for the thickness of the lining, and 8 lion prepregs are required for the removal of the lion. The present invention provides a heat _tree-like compound in the (four) point _ Shaped homogeneous solution, 200927789 The copper clad laminate made by it, with reference to IPC-TM-650, the glass transition heat delamination time, tan tin heat resistance (10). C), thermal expansion Wei, Caiji, electric constant and介 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ The following example is a detailed description of the present invention, but is not intended to limit the scope of the present invention. 〇Example 1 Preparation of MPGE/BMI prepolymer (hereinafter referred to as prepolymer I) (see Appendix 2): 21. 9 g MPGE (〇. 〇886equiv.), 31.7 g 4,4, _diamino The benzophenone-type bismaleimide (0.0885 equiv.) and 104.0 g of butyl hydrazine (solvent) were added to a three-sided bottom flask equipped with a reflux condenser, a gasifier and a thermometer, and (4) the atmosphere was heated up. To 8 ° ° C, slowly add 073.073 g of azobisisobutyronitrile (free radical initiator), reflux for 20 min, then add 〇. 〇 48 g hydroquinone (polymerization inhibitor), Cool to room temperature. A prepolymer I solution having a solid content of 34.0% was obtained. Example 2 Preparation of MPGE/BMI prepolymer (hereinafter referred to as prepolymer π) (see Table 2): Each reactant and method were the same as in Example 1, except that the amount of each reactant was changed to: 43 8 g 〇MPGE (0.177 equiv· ), 31.8 g of 4, 4'-diaminodiphenylmethane type bismaleimide (0.0885 equiv. ) 'butanone 147.1 g, azobisisobutyl cyanide. 1〇8 g , hydroquinone 〇〇 7 gram. A prepolymer II solution having a solids content of 34.0% was obtained. Table 2 Preparation of MPGE/BMI prepolymer into a single-quantity-one gjj prepolymer η epoxy resin MPGE 21.9 43.8 double maleimide 4, 4, -diaminodiphenylmethane type double horse醯iimine 31.7 31 8 initiator azobisisobutyronitrile 0.073 0.108 17 200927789 ❹ inhibitor solvent versus bisphenol butyl _ 0.048 104.0 0.070 147 Prepolymer I synthesis reaction equation 0 ΜΡ 6Ε

Synthetic reaction equation for Prepolymer II:

Copolymerization product in Prepolymer II The thermosetting resin compositions of Examples 3 to 14 and Comparative Examples 1 to 3: The formulations of the respective examples are shown in Table 3 and Table 4. 18 200927789 Ο Table 3 Resin composition of Examples 3-10 Formulation ingredients 3 4 5 Example 6 7 8 9 10 Prepolymer prepolymer I (100. 〇%) 70.1 39.6 70.1 39.6 70.1 39.6 70.1 39.6 陴 剤 剤 剤Bisphenol A epoxy resin (loo%) styrene-maleimide copolymer 29.8 16.8 29.8 16.8 29.8 16.8 29.8 16.8 SMA3000 103.6 58.5 103.6 58.5 103.6 58.5 103.6 58.5 Enhanced MBS core-shell particles (loo%) 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Accelerator 2-Ethyl-4-mercapto-flavor u sitting 0.006 0.006 0.006 0.006 0.006 0.006 0.006 0.006 Packing Nitrile Ming 88.5 177.0 Melting Dioxide 88.5 177.0 Oxidation Ming 88.5 177.0 Burning Kaolin 88.5 177.0 Solvent Butanone 205.0 205.0 205.0 205.0 205.0 205.0 205.0 205.0

Table 4 Resin Composition Formulations of Examples 11-14 and Comparative Examples 1-3 Example 12 13 14 1 Comparative Example 2 3 Prepolymer MPGE (100.0%) Prepolymer 1 (100.0%) Prepolymer 11 ( 100.0%) Flame Retardant 59.9 42.5 48.5 34.4 46.3 32.9 96.6 Brominated bisphenol A epoxy resin (loo%) Styrene-maleimide copolymer 32.0 22.7 51.4 36.5 35.1 24.9 41.0 SMA3000 Toughener 111.6 79.3 103.7 73.7 122.2 86.7 142.7 MBS core-shell particles (loo%) accelerator 3.0 3.0 3.0 3.0 3.0 3.0 3.0 2-ethyl-4-mercapto-methane sitting filler 0.004 0.004 0.004 0.004 0.004 0.004 0.004 spherical cerium oxide (SS0030) solvent 88.5 147.5 88.5 147.5 88.5 147.5 0.0 Butanone 205.0 205.0 205.1 205.0 205.0 205.0 217.0 The molar ratio of BMI to MPGE in the prepolymer I and prepolymer II formulations (hereinafter referred to as MR) 19 200927789 : Others are 1, 1 and 1: 2, Example 3 to Example 10, the filler ratio is 30% or 60% (mainly in order to investigate the effect of different fillers and their contents on the performance of the substrate); in the formulation of Example 11 and Example 12, the filler _ Write and 5Q%; in Example 13 and Example Μ Formulation, filler ratio 3G / and 50%, but the content of desert in the system increased, reaching 13.5% (excluding the weight of the filler and the leg K Note: the content of the desert in the formulation of Example 3 to the actual 12 is please); Comparative Example 1 and 2 is no BMI, the filler ratio is 30% and 50% respectively; in the formulation of Comparative Example 3, the MR is 1:1 'and no filler is added. The third embodiment will be described as an example. In a container equipped with a high-speed drop device, put 7 〇. j 克前为物I '加加205. 0 g butanone and 29. 8 g desertified double anti-epoxy resin (10) butanone solution '% Oxygen 1 400) 'Introduction' followed by sequential addition of 1 〇 3. 6 g of skimmer (small amount added in batches) '3.0 g MBS core shell particles, 〇.0 〇 6 g 2_ethyl _4 曱Gimami (added after dilution with pulse) 'Add slowly 88. 5 grams of nitriding. Stir for 1 hour or more and let stand. For ease of preparation, the prepreg was prepared by hand impregnation. The blue glass fiber cloth was immersed in the above resin solution, sized, and baked at 155 t for 3_5_ to prepare a drilled sheet in a semi-cured state. The prepreg with a number of sheets of 7628 (or 106) glass fiber cloth dipped in the above resin is superimposed and aligned, and the electrolysis copper of the upper and lower gi-sheets lQZ is swayed under the true pressure machine towel, the secret force 4Q_9 〇〇 psi Q The temperature is increased from 8 (rc to 200 ° C in 30 min, then hot-pressed at 20 ITC for 120 min, and then cooled to room temperature in 30 min to make a double-sided copper clad laminate with a certain thickness. Generally, the thickness of the 〇 需要 needs to be 5 7628 prepreg (or 20 sheets of 1〇6 prepreg), h 6mm requires 8 7628 prepregs. 7628 glass cloth pressed substrate for characteristic testing (such as glass transition temperature, peel strength, CTE, heat resistance, water absorption, Flame retardant, dielectric, etc.), 1〇6 glass cloth pressed substrate for thermal conductivity test. Refer to IPC-TM-650 for copper clad laminates. The test results are shown in Tables 5 and 6, which are summarized later. 20 200927789 Table 5 Example 3-10 substrate characteristics

Example 3 4 5 6 7 8 9 10 Glass transition temperature (DSC), °C 215.3 214.5 216.1 215.7 215.7 215.2 217.6 216.4 Glass transition temperature (TMA), °C 200.2 199.7 200.8 200.1 200.8 200.3 201.7 200.8 Copper foil peel strength (loz ), lb/in 8.1 7.1 8.2 7.3 8.3 7.4 7.9 7.0 Z-axis CTE (before Tg) (TMA), ppm/°C 34.7 26.7 31.1 23.1 25.6 20.5 30.4 21.3 Z-axis CTE (after Tg) (TMA), ppm/° C 188.0 157.1 169.9 124.5 165.7 129.8 181.9 130.6 Z-axis CTE (50-26 (TC) (TMA), % 2. 28 1.76 2.09 1.52 2.01 1.27 2,19 1.63 X-axis CTE (TMA), ppra/°C 11.9 11.3 11.4 11.0 11.2 10.8 11.7 11.0 Y-axis CTE01A), ppm/°C 12.2 11.6 11.7 11.3 11.5 11.0 12.0 11.4 T288 (THA),min >60 >60 >60 >60 >60 >60 >60 &gt ;60 T300 (TMA), min 15.6 11.5 41.5 40.6 40.5 40.7 51.3 49.2 Td (5% weight loss), °C 358.9 358.8 365. 1 363.6 363.7 363.8 367.6 365.7 Water absorption (D-23/24), wt% 0.006 0.005 0.006 0.005 0.006 0.005 0.007 0.006 Water absorption (PCT* 5hr), wt% 0.140 0.134 0.136 0.131 0.140 0.133 0.145 0.139 Solder to heat (PCT*5hr+ 288°C Solder dip) >10min >10min >10min >10mia >10min >10min >10min >10min X/Y axis thermal conductivity, ff/mk 2. 53 3.24 1.11 1.45 1.78 2.34 1.24 1.57 Z-axis heat conduction Rate, W/mk 1.39 1.83 0.58 0.76 0.92 1.23 0.68 0.84 Dielectric constant (1G/Hz) 3.83 3.87 3.76 3.81 3.85 3.90 3. 84 3.88 Dielectric loss factor (IG/Hz) 0.007 0.006 0.007 0.006 0.007 0.006 0.007 0.006 Flame retardancy (UL-94, rating) V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 Table 6 Example 11-14 and Comparative Example 1-3 Substrate Characteristics Example Comparative Example 11 12 13 14 1 2 3

Glass transition temperature (DSC), °C 205.6 205.8 201.7 200.9 173.1 172.5 207.7 Glass transition temperature (TMA), °C 191.2 190.6 188.2 187.6 159.6 158.4 192.5 Copper foil peel strength (loz), lb/in 8.2 7.4 8.3 7.5 7.9 7.0 8.6 Z-axis CTE (before Tg) (TMA), ppmA: 32.3 25.1 32.1 24.7 41.1 33.9 50.2 Z-axis CTE (after Tg) (TM), ppmA: 172.9 126.5 171.3 125.5 210.7 182.5 276.8 Z-axis CTE (50-260 ° C) (raA),% 2,19 1.82 2.15 1.63 2.87 2. 53 3.15 X-axis CTE(TMA), ppm/°C 11.4 11.1 11.4 11.0 12.8 12.2 14.4 Y-axis CTE(TMA), ppm/t 11.7 11.5 11.7 11.4 13.5 12.6 15.4 T288 (TMA), rain >60 >60 >60 >60 >60 >60 >60 T300 (TMA), rain 40.5 39.7 40.3 38.6 36.5 34.6 42.4 Td(5% weight loss), ° C 363.1 363.3 363.3 359.6 362.1 361.6 363.8 Water absorption (D-23/24), wt% 0.007 0.006 0.007 0.006 0.009 0.008 0.010 Water absorption (PCT* 5hr), wt% 0.146 0.143 0.147 0.142 0.185 0.181 0.245 Solder heat resistance (PCT* 5hr+ 288°C solder dip) >10min >10rain >10min MOrain >10min >10min >10rain X/Y axis thermal conductivity, w/r Ok 1.13 1.38 1.12 1.39 1.08 1.27 0.47 Z-axis thermal conductivity, 0.59 0.70 0.58 0.71 0.54 0.64 0.34 Dielectric constant (1G/Hz) 3. 75 3.82 3.76 3.83 3.92 3. 93 3.70 Dielectric loss factor (1G/Hz) 0.007 0.006 0.007 0. 006 0.008 0.007 0.010 Flame retardancy (UL-94 * rating) V-0 V-0 V-0 V-0 V-0 V-0 V-0 21 200927789 Since the following test methods are common methods in the field Therefore, the specific detection steps will not be described in the text. VIII 1) Glass transition temperature (Tg) The glass transition temperature refers to the temperature (X:) corresponding to the transition of the sheet from a glass state to a high-elastic state (rubber state) under heat. ‘ " Detection method: The results of differential scanning calorimetry (DSC) and thermomechanical analysis (ΤΜΑ)β indicate that the plate has a high glass transition temperature (Tg) of 2〇〇. 〇 (DSC). Ο Ο 2) Thermal decomposition temperature (Td) The thermal decomposition temperature (Td) is the temperature at which the sheet is thermally decomposed by heat (^. Detection method: Thermogravimetric analysis (TGA) is used. The condition is: heating rate 1 (rc/^· weight loss is 5%. '... The results show that the sheet has a high thermal decomposition temperature, Td reaches 355 < 3 (: above. 3) Thermal stratification time (τ-300) Τ-300 heat score The layer time refers to the plate at the set temperature of the c. Because of the layered listening, in the slave lining __. ”,, where the detection method appears. The thermomechanical analysis method (^like) is used. The higher thermal stratification temperature and thermal stratification time u are lower than those of Examples 3 and 4 (but still have 15.6 _ and u. 5 bis, respectively, for more than 40 min. The rest are 4). Solder heat resistance continues. Solder heat resistance ' means that the board is immersed in 288. (: In the molten solder, there is no (four) layering and the method of detecting the package. The substrate after the button is cut into 5. 〇 χ 5. 〇 尺寸 尺寸, 板, 目Sanding with sandpaper, steaming with high-pressure crane for a certain period of time, put 288 = use _ lOmin, observe the phenomenon of delamination, etc. The results show that the plates have excellent solder heat resistance, 8.1 under the armpit, duration 22 200927789 are above lOmin. 5) Thermal expansion coefficient (CTE) Thermal expansion (CTE) is the contact material under the subject, The unit temperature changes. The CTE of the sheet has a great relationship with the temperature conditions, especially the thickness of the cte ^ is very different when the temperature exceeds Tg and below Tg. = The thermal expansion coefficient of the substrate material The requirement is that the sheet should have a thermal expansion coefficient matching with Si to ensure compatibility with the Si wafer package. Ο Ο Detection method: Thermomechanical analysis (TMA) is used. The knot is bright, and the sheet is excellent under heat. Dimensional stability and very low cte, X/Y axis CTE < 12ppm / ° C, Z axis CTEC 13 ppm / t. 6) Water absorption rate Water absorption rate refers to the plate can be cooked under certain conditions, such as high pressure field for a certain period of time The ratio of the quality of the adsorbed water to the dry quality of the sample. Detection method: Cut the etched substrate into 5. 〇_5· 〇 coffee size, the edge of the board is polished with 6 〇〇 and 1200 mesh sandpaper in turn '1Q5t baking 2hr, then use high pressure steel to cook The results show that after 5 hours of PCT, the water absorption rate of the board is lower, both below 16%. Thermal conductivity The thermal conductivity is defined as the ability of the board to directly conduct heat, or thermal conductivity. The cross-section and length of the miscellaneous material are in unit temperature difference and the heat of direct conduction. The higher thermal conductivity can prevent the multi-layer substrate from overheating. Detection method: laser scattering method, according to ASTM E-1461 standard. It has a high thermal conductivity, and it can be guaranteed on the X/Y axis at h 〇w /m.k, and the Z-axis can be ensured at 〇.55W/m.k, indicating good thermal conductivity. 8) Dielectric constant and dielectric loss factor The dielectric properties of the electronic packaging material are important factors affecting the operation speed of the integrated circuit. The dielectric constant is too high, and the built-in power is increased. 200927789 Causes severe distortion of the signal during transmission. Therefore, the dielectric constant and dielectric loss factor are two important indicators for characterizing the high-frequency properties of materials. Detection method. The etched substrate was cut into 5· 〇ππηχ5. The enamel size, the edge of the board was sequentially polished with 1200 mesh sandpaper for hr for 2 hr, and then tested on a high resistance meter. The results show that the dielectric constant and dielectric loss factor of the sheet are low. The dielectric constant of the sheet at 1 GHz is 3.7 to 3.9, and the dielectric loss angle factor is 〇〇〇6_〇〇〇7. 9) Flame resistance Side removal of surface copper foil 'Prepare and test according to the flammability test of UL94 laminate. The results show that the ignitability of the sheet can reach 94V-0. It can be seen from the comparison of Examples 3-14 with the ratio 2 that the characteristics of the copper clad laminate made of the thermosetting resin composition prepared by the prepolymer provided by the present invention are more than that of the CCL plate made of MpGE alone. High Tg tree heat, low CTE (coefficient of thermal expansion) and water absorption, and better dielectric properties and heat (4) performance. In addition, no filler was added to the cap compound of Comparative Example 3, and its CTE (thermal expansion wire) and The water absorption rate is much higher than that of the resin composition to which the filler is added, and the heat conduction performance thereof is relatively recorded, and the copper-clad laminate which is reduced by the thermosetting tree which is finely applied has excellent substrate characteristics. The thermosetting resin composition prepared by the prepolymer provided by the invention has the advantages of low water absorption compared with the existing epoxy resin, and improves the sensitivity of the epoxy resin to water sensitivity under high temperature and high humidity conditions; The cyanate vinegar resin is low in price and low in water absorption, which has the disadvantages of high brittleness after curing. 3. It can be dissolved in the organic solvent and easy to process with the existing bimaleimide resin. And high-yield thermal shock; [Compared with the existing BT resin, the price is low, easy to process, and a stable solution in various low-foam solvents, improving the shortcomings of the high-high after curing. In summary, the copper clad laminate material manufactured by the present invention has a high glass transition temperature (Tg), excellent dielectric properties, low water absorption, high thermal shock resistance and Excellent thermal conductivity and other characteristics, - bloating coefficient 'feature requirements, due to its wide range of applications for special low-profile package carriers. Force W to push the 1C package substrate material [Simple description of the diagram] None [Main component symbol description] None

Ο 25

Claims (1)

200927789 X. Patent application scope L A prepolymer 'characterized by: {Malayimide phenyl ketal resin and 4, 4 - diaminobenzophenone bismaleimide as reactants The reaction is initiated by a free radical initiator in a solvent, and a polymerization inhibitor is added after the reaction. The molar ratio of BMI to hydrazine is 〇 to 0.5'. The amount of the initiator is 〇〇1% of the total molar amount of the reactant monomers. 15% •, the solvent dosage is 5G%-7G% of the total amount of the reactants; the resistance (4) is the amount of the lion-dependent amount—half to one times, as shown in the first paragraph of the patent application. a prepolymer wherein the solvent is one or more of a propyl group, a quinone benzene, a cyclohexanone, a dioxane, a methyl ethyl ketone or a methyl isobutyl ketone. 3. A prepolymer according to claim 1, wherein the initiator is an azo initiator. The reaction temperature is controlled at 60-90 ° C, and the reaction time is controlled at 10 - 60 min. 4. A prepolymer according to claim 1, wherein the initiator is a peroxide-based initiator, wherein the reaction temperature is controlled at 10 to 130 ° C, and the reaction time is 10 to 60 minutes. 5. A prepolymer according to claim 1, wherein the polymerization inhibitor is one of an anthraquinone, an aromatic nitro compound, a volatile metal salt electrophilic substance, a phenol or an amine substance or Several. 6. A prepolymer according to claim 1, wherein the molar ratio of BMI to MPGE is from 0.25 to 0.475. 7. A prepolymer as described in claim 1 wherein the amount of the initiator is 〇. 05% - 〇. 10% of the total moles of the reactant monomers. 8. A prepolymer according to claim 1 wherein the amount of solvent is from 60% to 70% by weight based on the total weight of the reactants. A thermosetting resin composition prepared by using a prepolymer according to the first aspect of the invention, which comprises the following components: (1) a prepolymer according to claim 1 The 5%-47. 0%; 5%-47. 0%; 5%-47. 0%; (3) at least one filler, which accounts for 2% to 6% by weight of the solids of the composition; (4) at least one solvent's solvent is added in an amount of 20 Π/ of the composition weight 26 200927789. (5) At least one type of flame retardant that can be used in the CCL industry. 10. The invention relates to the invention, wherein the styrene-A-maleic anhydride oligomer has a molecular weight ranging from 1400 to 50,000. 5%-38. 0%。 The 5% by weight of the solids of the composition of the composition of the weight of the composition of the composition of the composition of the composition of the composition of the invention. 12. The thermosetting resin composition according to claim 9, wherein the filler is crystalline cerium oxide, molten cerium oxide, spherical cerium oxide, aluminum oxide, mica, talc, boron nitride, One or more of nitriding, carbon carbide, diamond, smoldering clay, oxidized, nitrite or fiberglass. The thermosetting resin composition according to claim 9, wherein the solvent comprises a mixture of one or more of propionium, methyl ethyl ketone, decyl isobutyl ketone, toluene or dichloro decane. 00%_32. 5%。 The thermosetting resin composition as described in claim 9 wherein the flame retardant is a desertified double-anti-A epoxy resin, 00%_32.5% by weight of the composition solids. 27 200927789 VII. Designated representative map: (1) The representative representative of the case is: None. (2) A brief description of the symbol of the representative figure: 〇8. If there is a chemical formula in this case, please disclose the chemical formula that best shows the characteristics of the invention: 200927789 Patent description of the invention (the format, order and bold characters of this manual, please do not change , ※Please do not fill in the mark) ※Application number··qi yy ※Application period: γ ς 3 1 Category: 〇 about 1 (2006*0<i) ( 7 \ 7^/^(2006.01} I. Invention name: (Chinese / English) 卟丨1^3/^ θ Wei,: a prepolymer and a thermosetting resin composition made of the prepolymer. 2. Applicant: (Total 2 persons) Name: (Chinese/English) Ο 1. Dongguan Lianmao Electronic Technology Co., Ltd. 2 Representative of Lianmao Electronics Co., Ltd.: (Chinese/English) 1. Wan Haiwei 2. Wan Haiwei Residence or Business Office Address: (Chinese / English) 1. North Gate Village, Humen Town, Dongguan, Guangdong, China 2 No. 22, Industrial First Road, Pingzhen City, Taoyuan County ^ Nationality: (Chinese/English) 1. Mainland China 2. Republic of China III. Inventor: (Total 2 persons) Name: (Chinese/English) 1. He Yufang 2. Su Lijun Nationality :(Chinese/English) 1. Mainland China 2. Mainland China