JPH09283659A - Ic package board and manufacture of ic package using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a uniform and sufficient thickness and improve contactability with a board, by positioning a ceramic green sheet formed in a frame shape for surrounding a pattern onto a board having an IC mounting circuit pattern formed thereon, then transferring and firing the ceramic green sheet, and forming a resin sealing dam on the board. SOLUTION: On a board 1 having an IC mounting circuit pattern 4 formed thereon, a ceramic green sheet formed in a frame shape for surrounding the pattern 4 is positioned, transferred and fired, thus forming a resin sealing dam 13 on the board. Then, after an IC 2 is mounted, a hardening resin 9 is injected into an area surrounded by the dam 13 so as to seal the IC 2. Thus, since a ceramic frame having a thickness of several hundred μm to several mm may be easily formed on the minute board 1, almost all the ICs 2 may be securely resin-sealed. Also, since it suffices to charge the resin into the dam 13, significant reduction in cost is enabled and the package size may be minimized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC (integrated circuit) package substrate and a method for manufacturing an IC package using the same. More specifically, an IC package substrate suitable for resin encapsulation and resin encapsulation using the same I
The present invention relates to a method of manufacturing a C package.

[0002]

2. Description of the Related Art With the progress of advanced integration technology of semiconductor circuits, miniaturization and high performance of electronic devices are being spurred. For this reason, there is a strong demand for miniaturization and higher functionality of the IC package corresponding to the miniaturization of the IC bare chip. Conventionally, an IC package has been manufactured by mounting a bare IC chip on a mounting substrate or a lead frame by a wire bonding (W / B) technique using an Au or Al material, and then sealing the IC to protect it from the external environment. It goes through the process.

The IC is sealed by a confidential sealing method in which a metal cap is resistance-welded to the substrate in an inert gas atmosphere such as dry nitrogen gas, or a ceramic cap is brazed to shield from the external atmosphere. , There is a non-secret sealing method that seals the mounted chip with resin. The confidential sealing method is excellent in environment resistance and heat resistance, but it is costly to manufacture. For this reason,
Generally, a cheaper resin sealing method is often adopted,
As the performance of the encapsulating resin improves, the product applications to which the resin encapsulation method is applied are expanding.

Typical resin sealing methods include a transfer molding method and a coating method using a dispenser.
In the transfer molding method, the IC bare chip (2) is bonded onto the substrate (1) with a conductive adhesive (3), etc., as shown in the cross-sectional view of FIG. Conductor (5) with the circuit pattern (4) for IC mounting on the board surface
After connecting via the mold, the mold (6) is pressed onto the substrate, and the heat-curable curable resin is passed through the runner (8) in the cavity (7) formed between the substrate and the mold. It is a method of high-pressure transfer in the direction. After cooling, the mold is removed to obtain a resin sealing layer corresponding to the shape of the cavity. Although only one substrate is shown in the figure,
Actually, molding is performed on an original substrate on which a plurality of substrate regions are formed by using a mold having recesses corresponding to the respective regions.

In the transfer molding method, it is possible to perform sealing in an arbitrary shape by designing the mold, and it is possible to set the sealing height (h) on the substrate uniformly. However, since a mold is required, there is a cost problem, and it is difficult to design a mold having a minimum size according to the miniaturization of IC. Further, from these points, there is a drawback that it is not suitable for small-lot production. Further, since it is necessary to press the mold with a high pressure so as to withstand the high-pressure transfer of resin, it is difficult to apply it to a thin ceramic substrate.

The coating method using a dispenser is
Melt liquid sealing resin using a dispenser
It is a method of pouring on a bare chip. This method does not require a mold and is advantageous in terms of cost. Also suitable for small lot production. However, as shown in FIG. 2, the sealing resin may spread widely on the substrate surface, and the thickness of the sealing resin on the IC chip may not be sufficiently secured, and the height of the sealing layer (9) may increase. Since it decreases toward the part, the sealing of the chip may be insufficient. It is possible to increase the sealing height uniformly by increasing the viscosity of the resin, but the high-viscosity resin has a problem in the adhesion to the substrate. A frame (1
A method of printing (0) and adjusting the sealing shape by this is also known (FIG. 3), but in this method, the thickness of the frame is at most 10
The thickness is about 0 μm (0.1 mm), and there is a problem that the resin flows beyond the frame depending on the type and amount of the resin and lacks certainty. Further, since the ratio of the sealing height / sealing area is limited by the surface tension of the resin, the curing speed, etc.,
It is difficult to respond to miniaturization of the mounting board.

[0007]

DISCLOSURE OF THE INVENTION The present invention has a uniform and sufficient thickness and excellent adhesiveness to a substrate in the resin sealing technique using a dispenser, which has a low initial cost and is suitable for small-lot production. It is an object of the present invention to provide an improved method for surely forming a sealing resin layer.

[0008]

The present inventors have previously invented "a ceramic metal composite substrate and a method for forming an insulating protective film for the substrate" (Japanese Patent Publication No. 7-50820). According to the present invention, a ceramic green sheet made of glass or glass, an inorganic filler and an organic binder is transferred to a ceramic circuit board and fired to form an insulating protective film. The present invention has been completed by finding that it is possible to perform reliable resin encapsulation at an arbitrary encapsulation height by using an insulating film as a dam for encapsulation resin.

That is, the present invention provides the following IC package substrate. (1) On a substrate on which an IC mounting circuit pattern is formed,
A substrate for an IC package, characterized in that a ceramic green sheet formed in a frame shape surrounding the pattern is aligned, transferred, and fired to form a dam for a sealing resin on the substrate. (2) The substrate for an IC package according to claim 1, wherein the ceramic green sheet contains an inorganic material containing glass as a main component and an organic binder.

The present invention also provides the following IC package manufacturing method using the IC package substrates 1 and 2 described above. (3) On a substrate on which an IC mounting circuit pattern is formed,
A frame-shaped ceramic green sheet that surrounds the pattern is aligned, transferred, and fired to form a dam on the substrate, then the IC is mounted, and then cured in the region surrounded by the dam. A method for manufacturing an IC package, which comprises injecting a conductive resin to seal the mounted IC.

Furthermore, the present invention provides the following IC package manufacturing method in which the above-mentioned method 3 is applied to an aggregate substrate. (4) A ceramic green sheet formed in a grid pattern on a synthetic resin film is aligned on a substrate having a plurality of IC mounting areas so that each area is surrounded by each frame of the grid, and transferred. After firing to form a dam on the substrate surrounding each of the regions, the IC is formed in each region.
The method for manufacturing an IC package is characterized in that the mounting and the injection of a curable resin are performed, and each region is cut into individual packages. (5) A guide hole having a small hole diameter is provided in the ceramic green sheet formed in the lattice shape, and at the time of transferring the green sheet, the substrate is fixed to a jig having a guide pin, and the guide pin is inserted into the guide hole. 5. The method for manufacturing an IC package as described in 4 above, wherein the alignment is performed by inserting.

The steps and elements constituting the present invention will be described below. [IC Package Substrate] The IC package substrate according to the present invention is a ceramic substrate (1) on which an IC mounting circuit pattern (4) is formed, as schematically shown in FIGS. 4 (a) to (b) and FIG. A ceramic frame (13) is formed on the upper part by a transfer method so as to surround the circuit pattern.

(A) Original Substrate A ceramic fired substrate is used as the substrate. The material is not particularly limited. For example, alumina substrate, mullite substrate,
Examples thereof include glass ceramic substrates and aluminum nitride substrates. It may be a single layer substrate or a multilayer substrate. There is no particular limitation on the thickness or size of the substrate. IC mounting circuit pattern (4)
For example, as shown in FIG.
As shown in (a), through holes (11) and via holes that penetrate the substrate (only examples of through holes are shown in the figure.)
It is preferable that the lead-out is connected to the terminal (12) on the back surface via the lead wire, but the present invention is also applicable to a board (see FIG. 7) in which lead portions extend from the circuit pattern on the board surface along the board surface. Is. The IC mounting circuit pattern and the through holes are formed according to a known method.

(B) Ceramic Green Sheet (b-1) Preparation of Green Sheet The ceramic green sheet used in the present invention has good adhesiveness to the above-mentioned original substrate and is fixed to the original substrate by firing.
In other words, as long as they can be integrated, it is possible
Glass-based ceramics as proposed in 0820 are preferred.

The glass-ceramic green sheet is obtained by forming a slurry obtained by mixing a glass material powder, an organic binder, and an inorganic filler optionally added with a solvent into a sheet shape. An example of the glass material is lead borosilicate (PbO · B ₂ O ₃ · SiO ₂ ).
Examples of the glass include borosilicate glass, zinc borosilicate glass, and alkaline earth metal borosilicate glass. The particle size and the like may be in accordance with a known example, and for example, a particle size of about 1 to 10 μm is preferably used. Examples of organic binders include acrylic binders made of methyl methacrylate, butyl methacrylate, methyl acrylate, acrylic acid, polyvinyl butyral, and the like. The blending amount is 3 to the above glass component.
It is up to about 30% by weight, preferably up to about 20% by weight. If it is less than 3% by weight, the effect as a binder is not sufficiently exhibited. Even if it is used in an amount of more than 30% by weight, the effect is not improved, and on the contrary, there arises a problem that volume shrinkage during firing becomes large.

If desired, an inorganic filler is added to adjust the fluidity. As the inorganic filler, alumina, mullite, zirconia, etc. are used. The compounding amount is up to about 60% by weight, preferably 20%, with respect to the above glass component.
Up to about wt%. If used excessively, the sinterability at the time of firing becomes low, and chips or the like are likely to occur during the IC assembling work, resulting in problems.

The above-mentioned glass component of which the particle size is controlled, and optionally an inorganic filler and an organic binder, are mixed with an organic solvent (eg, toluene, methyl ethyl ketone (MEK), isopropanol, etc.), a dispersant (eg, polyethylene glycol, fatty acid ester, etc. ), And a plasticizer (for example, dibutyl phthalate, polyethylene glycol, etc.) are mixed well to form a low-viscosity slurry. The viscosity at the slurry preparation stage may be about several hundred cps. Next, the obtained slurry is placed under reduced pressure to perform defoaming treatment that also serves as solvent removal and viscosity adjustment, and the slurry viscosity is adjusted to several thousand to several tens of thousands cps.

The defoamed and highly viscous slurry is applied onto a synthetic resin film, preferably with a doctor blade, taking care not to entrap bubbles, to obtain a sheet having a desired thickness. Examples of synthetic resin films include
Examples include inexpensive polyethylene terephthalate (PET), polyphenylene sulfide (PPS), and the like. PET with a silicon film baked on the surface to facilitate transfer
Is preferred. The thickness of the film is preferably about 50 to 200 μm so as to have sufficient strength in the treatment in the subsequent step. The thickness of the ceramic sheet depends on the height of the dam to be formed, but is usually about 0.04 to 2 mm.

(B-2) Molding of green sheet The obtained sheet has a predetermined shape, specifically, a size corresponding to the IC mounting area on the original substrate of (a) or a size larger than that. , A frame-like shape that can surround the area. Usually, a rectangular window having one side of 5 to 50 mm is opened. Examples of the window opening method include cutting with a cutter and punching with a mold. Cutting or punching may be performed together with the film while the green sheet is still formed on the synthetic resin film, or cutting or punching may be performed with the green sheet peeled from the film.
The width of the frame portion of the sheet (the width of the dam shown in FIG. 4 or FIG. 5) is usually about 0.5 to 10 mm, though it depends on the size of the substrate and the arrangement of the circuits on the substrate. If it is less than 0.5 mm, sufficient strength cannot be obtained, and there is a risk of deformation during processing such as transfer. Even if the width exceeds 10 mm, the effect is not significantly improved.

(B-3) Transfer Step Next, the ceramic green sheet is passed through the window to I
It is placed on the substrate so that the C mounting area is exposed on the surface and fixed by thermocompression bonding or an adhesive. The thermocompression bonding is performed, for example, by applying a pressure of about 10 to 200 kg / cm ² at a temperature of 30 to 150 ° C. Examples of the adhesive include binders used for green sheets, slurries having a green sheet composition, and the like.

(B-4) Firing step The ceramic substrate on which the sheet is fixed is heated in an oxidizing atmosphere (usually in an air atmosphere) to about 400 to 500 ° C. to remove the binder, and then 550 ° C. to 850 ° C. Bake at. The total heating time for debinding and firing is 3
It is about 0 minutes to 3 hours, and the firing time is about 5 to 20 minutes. By going through each of the above steps, a ceramic dam surrounding the IC mounting circuit pattern (4) on the substrate (1)
It is possible to obtain the IC package substrate (15) in which (13) is formed without affecting the characteristics of the substrate (FIG. 5).
(Corresponding to Figure 4 (b)).

[Method of Manufacturing IC Package] By mounting an IC on the IC package substrate manufactured as described above and further sealing with a resin, an IC package having excellent sealing performance can be manufactured. (Fig. 4 (b) ~
(d)).

The IC is mounted according to a known method. Specifically, the IC bare chip (2) is made into a conductive adhesive.
It is adhered to the substrate (1) by (3), and the circuit on the IC chip is connected to the IC mounting circuit (4) on the substrate by the conducting wire (5). Examples of the conductive adhesive include Ag-based epoxy resin and the like. The conductive wire is made of, for example, a metal having excellent conductivity and oxidation resistance such as Au or Al, and is connected by a wire bonding technique (FIG. 6 (corresponding to FIG. 4 (c))).

After the IC is mounted, a curable resin is poured into the space (14) surrounded by the substrate (1) and the dam (13) so that the IC (2)
To seal. Examples of the curable resin include epoxy resin and phenol resin. IC sealed with resin
The cross-sectional shape of the package is schematically shown in FIG. 4 (d) for a backside lead-out type package and in FIG. 7 for an IC package having a metal lead (4) on the substrate surface.

[IC Package Manufacturing Method Using Collective Substrate] By applying the IC package manufacturing method of the present invention described above to the collective substrate, the IC package can be efficiently manufactured. That is, as shown in FIG. 8A, a plurality of circuit patterns 22 are formed on one substrate 21. These circuit patterns (22) are exactly the same as the individual circuit patterns (4) described above, and are read out to the back surface of the substrate through through holes or the like. Such an aggregate substrate can be manufactured according to a known technique by using the same material as the individual substrate. Although FIG. 8 shows an example having 3 × 3 circuit patterns for convenience of description, in reality, a large number of circuit pattern regions can be provided on one aggregate substrate according to the size of the product. .

On the other hand, a green sheet (23), which is slightly larger than the above substrate, is formed on the synthetic resin film (24), and a window (25) is arranged in a size and size corresponding to the circuit pattern (22), and a green sheet is also formed. A plurality of small holes (26) are punched in the edge of the sheet (Fig. 8 (b)). The green sheet manufacturing method, perforation method, etc. are the same as described above. The diameter of the small holes is preferably about 2 to 8 mm, and when the guide pin described below is inserted, the circuit pattern
Arrange so that (22) and window (25) correspond exactly.

Next, the green sheet (23) is turned over so that the synthetic resin film (24) faces upward, and the window portion (25) is placed so as to overlap the circuit pattern (22) of the substrate (Fig. 8
(c)). At this time, the substrate (21) is a jig having a guide pin (28).
Small hole fixed to (27) and provided on the edge of the green sheet (23)
The guide pins (28) are passed through (26) to align them. With such a configuration, the alignment of the green sheet and the substrate can be easily and accurately realized by the arrangement of the guide pins and the small holes. Note that, although a jig having a shape in which two U-shaped members are combined is shown as an example in the drawing, the shape is not particularly limited as long as it is sufficient to fix the substrate. After that, peel off the film or from the film, press or bond the green sheet onto the substrate, and remove the jig (peeling the film if necessary)
After that, baking is performed. The procedures and conditions for pressure bonding, bonding and firing are the same as above. After cooling, the IC is mounted and the cured resin is injected into each circuit pattern area in the same manner as described above, and thereafter, the board is cut along the grid-shaped dams. It is possible to obtain an individual substrate.

[0028]

Example 1 [Ceramic green sheet] 10% by weight of alumina (average particle size 3.0 μm) and lead borosilicate glass (average particle size 3.0 μm)
m) 10 parts by weight of an acrylic binder (KCl-08 manufactured by Kyoeisha Co., Ltd.), 6 parts by weight of a plasticizer and 100 parts by weight of an inorganic material consisting of 90% by weight, and methyl ethyl ketone (ME).
K) 35 parts by weight were charged in a ball mill and mixed for several hours to obtain a slurry. This slurry was adjusted to about 10,000 cps in a vacuum defoaming machine, and ET was applied by the doctor blade method.
A continuous green sheet having a width of 48 cm and a dry thickness of about 500 μm was prepared on the film, and then cut into a size of 10 × 10 cm.

[Substrate] Low temperature sintered substrate (50% alumina,
A glass (50%) material was used to fabricate a collective substrate of 8 cm long × 8 cm wide × 0.6 mm thick for IC mounting. On the front surface of the substrate, 25 IC mounting regions made up of two IC electrodes formed by thick film printing were provided, and each of them was read out to the back surface via a via hole.

[Manufacture of IC Mounting Substrate] IC of the Substrate
25 windows (9 mm x 9 mm) were made on the green sheet manufactured earlier by an NC punching machine so as to correspond to the mounting area.
I opened one. At that time, four 2.4 mmφ guide holes were formed at the edge of the green sheet for alignment with the substrate. The substrate is fixed to a tungsten carbide (WC) jig having a guide pin with a height of 2.4 mm and a height of 5 mm as shown in FIG. 8, and the green sheet with the PET film surface facing upward is guided by the guide pin into the guide hole. It was placed on the substrate so that it would be inserted. After removing the jig, the substrate was thermocompression-bonded at a temperature of 80 ° C. and a pressure of 150 Kg / cm ² to 600
The ceramic dam was fixed to the IC mounting substrate by passing through a belt furnace adjusted to 30 ° C. for a total heating time of 27 Ω. The height of the dam after baking and fixing was about 300 μm.

After that, the width of the substrate is 200 μm with a die saw.
I made a break groove. A 0.6 mm thick ęC bare chip is attached to this substrate with a conductive adhesive (EN manufactured by Hitachi Chemical Co., Ltd.).
Then, the circuit on the substrate was connected to the IC electrode by Au wire bonding. On the thus mounted IC substrate, a sealing resin (KE6309 manufactured by Hitachi Chemical Co., Ltd.) was poured into a region surrounded by the ceramic dam with a dispenser and held at 125 ° C. for 4 hours to be cured.

By cutting the individual substrate along the break groove, the thickness of the base substrate is 0.6 mm and the height of the dam is
It was possible to manufacture a small IC package of 0.3 mm and a dam width of 0.5 mm and a size of 10 mm × 10 mm.

Example 2 An IC mounting substrate was prepared in the same manner as in Example 1 except that the material of the substrate was 96% alumina. IC mounting and resin sealing are performed in the same manner as in Example 1, and 10 mm × 10 mm
Manufactured a small IC package.

Comparative Example 1 When an IC was mounted on a conventionally used 96% alumina IC mounting substrate and a sealing resin was poured using a dispenser, the resin spreads on the substrate and the size of the package surface is increased. It was completely impossible to set the value to about 1 cm ² .

[0035]

According to the conventional printing method (FIG. 3), in order to form a frame having a thickness of about several hundreds of μm on the substrate, it is necessary not only to repeat the printing a large number of times but also to print the frame by overlapping the printing. Although it was difficult to actually use it due to the sagging of the paste for paste, etc., according to the method of the present invention, it is possible to easily form a ceramic frame having a thickness of several hundred μm to several mm on a minute substrate. Can do almost all ICs
With respect to the above, reliable resin sealing can be performed. Also,
According to the conventional transfer molding method, a large amount of cost was required for manufacturing the mold, but the method of the present invention only pours the resin by the dispenser into the dam formed by transferring the ceramic green sheet. , The cost can be significantly reduced, and the minimum required package can be manufactured.
In addition, a special device for high-pressure transfer and special consideration for applying high voltage to the substrate, which are required in the transfer molding method, are unnecessary.

Furthermore, since the method of the present invention uses the glass-based ceramics that can be fired at a low temperature, it does not adversely affect the IC mounting circuit. Furthermore, in the method of the present invention, since the collective substrate can be used as an original substrate, it is extremely useful in practice as a method for efficiently producing a high quality IC package.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of resin sealing by a conventional method (transfer molding method).

FIG. 2 is a sectional view showing an embodiment of resin sealing by a conventional coding method.

FIG. 3 is a sectional view showing an embodiment of resin sealing by a conventional coding method.

4A to 4D are schematic views showing an outline of a method for manufacturing an IC package according to the present invention in a series of sectional views.

FIG. 5 is a perspective view showing an example of an IC package substrate according to the present invention.

FIG. 6 is a perspective view showing a state in which an IC is mounted on an IC package substrate according to the present invention.

FIG. 7 is a sectional view showing another embodiment of the resin-sealed IC package according to the present invention.

FIG. 8A to FIG. 8C are schematic views showing a positioning process in a method for manufacturing an IC package using the aggregate substrate according to the present invention.

[Explanation of symbols]

1 ... Substrate, 2 ... IC bare chip, 3 ... Conductive adhesive, 4 ... IC mounting circuit pattern, 5 ... Conductor wire, 6 ...
… Mold, 7 …… cavity, 8 …… runner, 9 ……
Resin sealing layer, 10 ... Thick film printing frame, 11 ... Through hole, 12 ... Terminal, 13 ... Ceramic dam, 15 ...
... IC mounting board, 21 ... collective board, 22 ... IC mounting circuit pattern, 23 ... green sheet, 24 ...
Synthetic resin film, 25 ... Window, 26 ... Small hole, 27 ...
… Jig, 28… Guide pin

Claims (5)

[Claims] 1. A ceramic green sheet formed in a frame shape surrounding the pattern is aligned, transferred and fired on a substrate on which an IC mounting circuit pattern is formed to form a sealing resin dam on the substrate. A substrate for an IC package, which is formed. 2. The substrate for an IC package according to claim 1, wherein the ceramic green sheet contains an inorganic material containing glass as a main component and an organic binder. 3. A ceramic green sheet formed in a frame shape surrounding the pattern is aligned and transferred onto a substrate on which a circuit pattern for mounting an IC is formed, baked to form a dam on the substrate, and then the IC is formed. Is mounted, and thereafter, a curable resin is injected into the area surrounded by the dam to seal the mounted IC. 4. A ceramic green sheet formed in a grid pattern on a synthetic resin film is aligned on a substrate having a plurality of IC mounting areas so that each area of the grid is surrounded by each frame of the grid. After transferring and firing to form a dam surrounding each of the regions on the substrate, mounting of an IC and injection of a curable resin are performed in each region, and each region is cut into individual packages.
C package manufacturing method. 5. A guide hole having a small hole diameter is provided in the ceramic green sheet formed in the lattice shape, and when transferring the green sheet, the substrate is fixed to a jig with a guide pin, and the guide hole is provided with the guide hole. The method of manufacturing an IC package according to claim 4, wherein the alignment is performed by inserting a guide pin.