JPH0340519B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a high-density wiring board, and particularly to a module wiring board suitable for a multilayer wiring board.

[Background of the invention]

Traditionally, devices are equipped with integrated circuit chips such as ICs and LSIs.
Attempts have been made to use various materials as materials for insulating between metal wiring layers in a wiring board for making connections between chips. Among these, many attempts have been made to use organic polymer resins, which have a low dielectric constant and can be easily formed into thick films, in order to increase the propagation speed of electrical signals. for example,
JP-A-55-158697 discloses an example in which a liquid low-viscosity polyimide resin is heat-cured and used as an interlayer insulating layer of a multilayer wiring board.

The normal polyimide resin used here is
Since the coefficient of thermal expansion is as large as 4 to 7 × 10 ^-5 /K, the thermal stress after heat curing, that is, the stress caused by the difference in coefficient of thermal expansion between the material forming the substrate or wiring layer and the polyimide resin, becomes large. However, there were disadvantages in that the film was prone to peeling, cracking, deformation, and poor adhesion.

In addition, when reducing the capacitance between wiring layers, when increasing the thickness of the insulating layer or attempting to make the wiring multi-layered, the thickness of the multilayer wiring formed by laminating the wiring layer and the insulating layer increases. However, the warpage of the entire wiring board due to thermal stress increases. For this reason, there have been many problems in applying conventional polyimide resins as insulating layers between wiring layers of multilayer wiring, to the extent that photolithography for patterning the upper wiring layer is difficult.

However, the present inventors learned of the development of a new polyimide resin that has a lower coefficient of thermal expansion than ordinary polyimide resins, and by applying this as a material for insulating between the wiring layers of multilayer wiring, the resin can be improved. It has been found that many problems caused by thermal stress are solved. The present invention has been made based on this discovery.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and provide a wiring board that is highly reliable and allows easy formation of multilayer wiring.

[Summary of the invention]

The present invention has wiring for mounting an LSI chip,
A wiring board for a module in which a silicon or ceramic substrate is connected to a multilayer wiring consisting of a plurality of metal wiring layers and an insulating layer of aromatic polyimide insulating each wiring layer, wherein the wiring layer is made of the following (1) ) to (3), and one aromatic diamine selected from
A low thermal expansion aromatic polyimide obtained by reacting one tetracarboxylic dianhydride selected from (4) to (6), an aromatic diamine other than the aromatic diamine, and the tetracarboxylic dianhydride. A mixture of aromatic polyimides obtained by reacting with tetracarboxylic dianhydrides other than those mentioned above, or the following:
One aromatic diamine selected from (1) to (3), one tetracarboxylic dianhydride selected from (4) to (6) below, and an aromatic diamine other than the above aromatic diamine and the above tetracarboxylic diamine. It is characterized by being composed of a copolymerized aromatic polyimide containing at least one tetracarboxylic dianhydride other than an acid dianhydride.

(However, R is an alkyl group, a fluorinated alkyl group,
It is selected from an alkoxyl group, a fluorinated alkoxyl group, an acyl group, or a halogen, and l is an integer of 0 to 4. ) In the present invention, in order to prevent blistering, peeling, and poor adhesion of the insulating layer and to form a highly reliable wiring board, the adhesion between the insulating material, the wiring material, and the substrate material is important.

Wiring materials include copper, aluminum, gold,
Examples include silver, molybdenum, tungsten, nickel, palladium, and platinum.

Substrate materials include alumina, silicon carbide, silicon nitride, silicon, glass, etc., and their forms include, as is generally well known, silicon substrates and ceramic substrates with internal wiring incorporated therein.

In order to improve the adhesion between the insulating layer and these materials, the insulating layer is preferably a blend or mixture of a low thermal expansion polyimide and a non-low thermal expansion polyimide, or a copolymerized aromatic polyimide. It is preferable that there be.

For the insulating layer, it is desirable to use aromatic polyimide resin, which has a low dielectric constant, is suitable for high-speed propagation of electric signals, and has particularly excellent heat resistance. In addition, in order to reduce the capacitance between wiring layers, it is necessary to form an insulating layer with a thickness of 10 μm or more with good film thickness accuracy, and from this point of view as well, liquid coating is possible and thick formation is possible. It is desirable to use a simple aromatic polyimide resin.

The low thermal expansion polyimide applied to the present invention is
It can be obtained by homopolymerization of an aromatic amine dicarboxylic acid derivative or by reaction of an aromatic diamine and an aromatic tetracarboxylic acid derivative.

Specific examples of the aminodicarboxylic acid derivatives used in the synthesis of the low thermal expansion polyimide applied to the present invention include 4-amine phthalic acid, 4-amine phthalic acid,
-amino-5-methylphthalic acid, 4-(p-anilino)-phthalic acid, 4-(3,5-dimethyl-4-
Anilino) phthalic acid, or their esters, acid anhydrides, acid chlorides, etc.

Examples of aromatic diamines used in the synthesis of the low thermal expansion polyimide applied to the present invention include the following.

p-phenylenediamine, 2,5-diaminotoluene, 2,5-diaminoxylene, diaminodurene (2,3,5,6-tetramethyl-p-
phemylenediamine), 2,5-diaminobenzotrifluoride, 2,5-diaminoanisole, 2,5-diaminoacetophenone, 2,5-
Diaminobenzophenone, 2,5-diaminodiphenyl, 2,5-diaminofluorobenzene, benzidine, o-tolidine, m-tolidine, 3,
3',5,5'-tetramethylbenzidine, 3,3'-
Dimethoxybenzidine, 3,3'-di(trifluoromethyl)benzidine, 3,3'-diacetylbenzidine, 3,3'-difluorobenzidine, octaphthalobenzidine, 4,4''-diamineterphenyl, 4,4'' -Diamine quarterphenyl.

Moreover, these diisocyanate compounds can also be used in the same manner.

These can be generally expressed as (1) to (3) above.

Tetracarboxylic acid derivatives used in the synthesis of the low thermal expansion polyimide applied to the present invention include esters, acid anhydrides, and acid chlorides. In particular, it is preferable to use an acid dianhydride from the viewpoint of synthesis. Specific examples include pyromellitic acid, methylpyromellitic acid,
Dimethylpyromellitic acid, di(trifluoromethyl)pyromellitic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 5,5'-dimethyl-3,
3',4,4'-biphenyltetracarboxylic acid, p-
Examples include (3,4-dicarboxyphenyl)benzene, and acid anhydrides, acid chlorides, and esters thereof.

These are generally expressed in (4) and
It becomes like (6).

The synthesis reaction generally involves N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAC), dimethylsulfoxide (DMSO), dimethyl sulfate, sulfolane, butyrolactone, cresol, phenol,
It is carried out in a solution of halogenated phenol, cyclohexanone, dioxane, etc. at a temperature in the range of 0 to 200°C.

The polyimide with low thermal expansion applied to the present invention is obtained from an aromatic diamine and a tetracarboxylic acid derivative other than the above-mentioned aromatic diamine and tetracarboxylic acid derivative.

Specific examples of aromatic diamines include m-phenylenediamine, 4,4'-diaminodiphenylmethane, 1,2-bis(anilino)ethane, 4,
4'-Diaminodiphenyl ether, diaminodiphenyl sulfone, 2,2-bis(p-aminophenyl)propane, 2,2-bis(p-aminophenyl)hexafluoropropane, 3,3'-dimethyl-4,4' -diaminodiphenyl ether, 3,
3'-dimethyl-4,4'-diaminodiphenylmethane, diaminotoluene, diaminobenzotrifluoride, 1,4-bis(p-aminophenoxy)benzene, 4,4'-bis(p-aminophenoxy)biphenyl, 2, 2-bis{4-p-aminophenoxyphenyl)}, propane, diaminoanthraquinone, 4,4'-bis(3-aminophenoxyphenyl)diphenylsulfone, 1,3-
Bis(anilino)hexafluoropropane, 1,
4-bis(anilino)octafluorobutane,
1,5-bis(anilino)decafluoropentane, 1,7-bis(anilino)tetradecafluorobutane, general formula or Diaminosiloxane, 2,2- _bis { _{4- ( p} -aminophenoxy)phenyl}hexafluoropropane, 2,2-bis{4-(3-aminophenoxy)
phenyl}hexafluoropropane, 2,2-bis{4-(2-aminophenoxy)phenyl}hexafluoropropane, 2,2-bis{4-(4
-aminophenoxy)-3,5-dimethylphenyl}hexafluoropropane, 2,2-bis{4
-(4-aminophenoxy)-3,5-ditrifluoromethylphenyl}hexafluoropropane,
p-bis(4-amino-2-trifluoromethylphenoxy)benzene, 4,4'-bis(4-amino-2-trifluoromethylphenoxy)biphenyl, 4,4'-bis(4 -amino-3-trifluoromethylphenoxy)biphenyl, 4,4'-bis(4-amino-2-trifluoromethylphenoxydiphenyl sulfone, 4,4'-bis(3-amino-5 -trifluoromethylphenoxy)diphenylsulfone, diamines such as 2,2-bis{4-(4-amino-3-trifluoromethylphenoxy)phenyl}hexafluoropropane,
and diisocyanates obtained by the reaction of these diamines with phosgene, such as tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, diphenyl ether diisocyanate, phenylene-1,
There are aromatic diisocyanates such as 3-diisocyanate.

Further, examples of the tetracarboxylic acid derivatives include the following. Although tetracarboxylic acids are exemplified here, esterified products, acid anhydrides, and acid chlorides thereof can of course also be used. 2,
3,3',4'-tetracarboxydiphenyl, 3,
3',4,4'-tetracarboxydiphenyl ether, 2,3,3',4'-tetracarboxydiphenyl ether, 3,3'4,4'-tetracarboxybenzophenone, 2,3,3 ',4'-Tetracarboxybenzophenone, 2,3,6,7-tetracarboxynaphthalene, 1,4,5,7-tetracarboxynaphthalene, 1,2,5,6-tetracarboxynaphthalene, 3,3 ',4,4'-tetracarboxydiphenylmethane, 2,2-bis(3,4
-dicarboxyphenyl)propane, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane, 3,3',4,4'-tetracarboxydiphenyl sulfone, 3,4,9,10 -tetracarboxyberylene, 2,2-bis{4-(3,
4-dicarboxyphenoxy)phenyl}propane, 2,2-bis{4-3,4-dicarboxyphenoxy)phenyl}hexafluoropropane,
Examples include butanetetracarboxylic acid and cyclopentanetetracarboxylic acid.

The blending ratio of these aromatic diamines and tetracarboxylic acid derivatives to the aromatic diamines and tetracarboxylic acid derivatives (1) to (6) described above is preferably 20% or less.

In addition, modified with a compound having a reactive functional group,
It is also possible to introduce a cross-linked structure or a ladder structure.
For example, there are the following methods.

(i) By modifying with a compound represented by the following general formula, a pyrrolone ring, isoindoquinazolinedione ring, etc. are introduced.

Here, R′ is a 2+x-valent aromatic organic group, Z
is a group selected from NH ₂ group, CONH ₂ group, and SO ₂ NH ₂ group, and is in the ortho position with respect to the amino group. x is 1 or 2.

(ii) Modify with an amine, diamine, dicarboxylic acid, tricarboxylic acid, or tetracarboxylic acid derivative having a polymerizable unsaturated bond to form a crosslinked structure upon curing. Unsaturated compounds include maleic acid, nadic acid, tetrahydrophthalic acid,
Ethinylaniline and the like can be used.

(iii) It is modified with an aromatic amine having a phenolic hydroxyl group or a carboxylic acid, and a network structure is formed using a crosslinking agent that can react with the hydroxyl group or carboxylic acid group.

In addition, in order to improve the adhesion between the rejection layer and the wiring and substrate, it is necessary to roughen the material surface or use a silane coupling agent, titanate coupling agent, aluminum alcoholate, aluminum chelate, zirconium chelate, aluminum acetylacetone, etc. A method involving surface treatment is preferred. These surface treating agents may be added to the aromatic polyimide.

Furthermore, when forming a multilayer broken line in the present invention, adhesion between resins is also important as insulating films are laminated, and this can also be done using the same method as the adhesion improvement treatment for insulating materials and substrate materials. Just apply.

In addition, in order to lower the coefficient of thermal expansion, increase the modulus of elasticity, and control the fluidity of the polyimide that forms the insulating layer applied in the present invention, powders such as inorganic, organic, or metal may be added. , fibers, chopped strands, etc. can also be mixed.

[Embodiments of the invention]

FIG. 1 shows a cross-sectional view of a multilayer wiring board for an LSI module. 1 is a ceramic substrate, 2 is a wiring layer,
3 is an insulating layer using aromatic polyimide, 4 is LSI
On the chip 5, solder balls 6 for bonding are terminals for external connection, and 2 and 3 form a multilayer wiring.

A multilayer wiring board for a module uses silicon as the substrate 1, copper as the wiring layer 2, and conventional polyimide resin (thermal expansion coefficient 4×10 ^-5 /K) as the insulating layer 3. If it exceeds 40 μm, the board will warp significantly and the upper wiring layer (width
20 μm) patterning became difficult. Also,
When the rejection layer thickness exceeded 80 μm, peeling occurred at the boundary between the substrate and the insulating layer due to stress caused by the difference in coefficient of thermal expansion, and an upper wiring layer could not be formed.

On the other hand, in a module multilayer wiring board using low thermal expansion polyimide having the chemical structure shown in formula (A) as the rejection layer 3, the thickness of the multilayer wiring is 100 μm.
No problem occurred even when the temperature exceeded m.

In addition, in order to increase adhesion to the substrate, a polyimide resin is made by copolymerizing 3% of a low thermal expansion polyimide with a chemical structure shown in formula (A) with a polymer having a chemical structure shown in formula (B). When used as the insulating layer 3, the lifespan against thermal cycles was more than doubled compared to the case where polyimide consisting only of the chemical structure shown in formula (A) was used as the insulating layer.

In FIG. 1, a solder ball 5 is connected to a multilayer wiring using polyimide according to the present invention as an insulating layer 3.
When LSI chip 4 is mounted, the problem of fatigue breakage of solder balls no longer occurs because the difference in coefficient of thermal expansion between the chip and the insulating layer is small. Therefore, it has become possible to further miniaturize the size of the solder balls, and higher density packaging has been achieved.

Figure 2 shows a cross-sectional view of a super multilayer wiring board for LSI modules, which has not been possible in the past. In a module that implements the CPU of a large computer, many wiring layers are required to perform complex calculations, and extremely thick multilayer wiring must be formed. This was not possible with conventional polyimide resins because the thermal stress was too large. CPU module also
This was made possible by applying the polyimide according to the present invention. In particular, by skillfully controlling the thermal expansion coefficient of the aromatic polyimide applied to the insulating layer 3, the thermal expansion coefficient of the composite part (multilayer wiring part) of the distribution layer 2 and the insulating layer 3 in FIG. ,
If the coefficient of thermal expansion is made approximately equal to that of the LSI chip 4 and the ceramic substrate 1, most of the problems caused by thermal stress can be solved.

Figure 3 shows the multilayer wiring board for LSI module.
A cross-sectional view is shown in which a portion of a solder ball 5 for bonding is covered with an aromatic polyimide according to the present invention. By adopting this structure, the thermal stress applied to the solder ball portion 5 is suppressed, and the reliability of the chip connection portion is increased. Furthermore, similar effects were obtained even when not only the solder ball portion 5 but also part or all of the LSI chip 4 was covered with the polyimide according to the present invention.

Figure 4 shows the multilayer wiring board for LSI module.
A cross-sectional view of another embodiment is shown. The back side of the chip was placed directly on the multilayer wiring, and wire bonding or film carrier was used for the LSI chip 4, wiring layer 2, and connection portion 7. Thermal stress generated at the contact surface between the insulating layer 3 and the LSI chip 4 made of polyimide according to the present invention was small, and a highly reliable wiring board could be formed.

〔Effect of the invention〕

As explained above, according to the present invention, even when the thickness of the multilayer wiring is increased, warping of the wiring board and peeling of the film due to thermal stress can be prevented, and the wiring board can have fine wiring. Moreover, it becomes possible to form a high-density multilayer wiring board for modules with excellent reliability. In particular, when the number of wiring layers is large, the effect of damage due to thermal stress becomes large, so the effect of the present invention is large.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of a multilayer wiring board for a module, Figure 2 is a side sectional view of a super multilayer wiring board for a module, and Figures 3 and 4 are side sectional views of a multilayer wiring board for a module. be. 1...Substrate, 2...Wiring layer, 3...Insulating layer, 4
...LSI chip, 5... Solder ball for bonding, 6... Terminal for external connection, 7... Wire bonding or film carrier.

Claims (1)

[Scope of Claims] 1 A multilayer wiring having a wiring on which an LSI chip is mounted and consisting of a plurality of metal wiring layers and an insulating layer of aromatic polyimide insulating each wiring layer, and a silicon or ceramic substrate are connected. In the module wiring board, the insulating layer includes one aromatic diamine selected from the following (1) to (3) and one tetracarboxylic dianhydride selected from the following (4) to (6). A low thermal expansion aromatic polyimide obtained by the reaction, and an aromatic polyimide obtained by reacting an aromatic diamine other than the aromatic diamine with a tetracarboxylic dianhydride other than the tetracarboxylic dianhydride. A mixture, or one aromatic diamine selected from the following (1) to (3) and one tetracarboxylic dianhydride selected from the following (4) to (6), and an aromatic diamine other than the above aromatic diamine. 1. A wiring board for a module, comprising a copolymerized aromatic polyimide containing at least one of a diamine and a tetracarboxylic dianhydride other than the tetracarboxylic dianhydride. (However, R is an alkyl group, a fluorinated alkyl group,
It is selected from an alkoxyl group, a fluorinated alkoxyl group, an acyl group, or a halogen, and l is an integer of 0 to 4. )