JPH09260540A - Manufacture of package substrate for semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To get a recess excellent in the effect of lightening and suppressing stress concentration to a solder ball, etc., and raise the selectivity of the shape of a recess, the quality of material of a recess forming layer, etc., in the case of using a solder ball, etc., as a terminal for external connection. SOLUTION: An unbaked or baked ceramics multilayer wiring board 15', which has an electrode pad 14 made on the main face and an inner wiring layer (16) connected electrically to this electrode pad 14, is manufactured. Insulating paste 20 is applied on the surface where an electrode pad 14a is formed of this ceramic wiring insulating board 15' so that it may expose at least one part of the surface 14a of an electrode pad 14a and that it may swell from the surface 14a of an electrode pad. Then, the application face of this insulating paste 20 is hardened by the simultaneous baking with the ceramic board or heat treatment, thus an insulating layer 19 which has a recess 18 for installation of a solder ball, etc., is made. The inwall 18a of the recess 18 is given a taper with an angle θ.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor package base used as a base for a BGA package or the like.

[0002]

2. Description of the Related Art A high-performance, highly-integrated LSI package can be connected to an LSI at multiple terminals with a narrow pitch, has a high wiring density, has good heat dissipation, and can handle high-speed signals. What is needed is that the terminals themselves of the package can be multi-terminals with a narrow pitch. In order to satisfy such multi-terminal and narrow pitch of the package, the package structure is changed from the conventional pin insertion type to the QF type.
It is shifting to surface mount types such as P (Quad Flat Package) and BGA (Ball Grid Array).

Among the surface mount types, the BGA package using a bump connecting body (bump) made of a solder ball or the like as an external connecting terminal of the package can shorten the connecting distance by the terminal and can achieve high speed due to the inductance of the connecting portion. It is expected to be a high-performance and highly-integrated LSI package because it has the advantage of suppressing signal reflection and delay. In addition to shortening the connection distance, the BGA package also facilitates narrow pitch and multiple terminals by forming bumps. Furthermore, the narrow pitch and multiple terminals by forming bumps reduce the package size itself, making it suitable for printed circuit boards. It is expected that the packaging density will be improved, the electrical characteristics will be improved by reducing the parasitic capacitance, inductance, resistance, etc. of the wiring, and the high frequency characteristics will be improved by downsizing the package.

On the other hand, the power consumption tends to increase with the increase in the speed and integration of the LSI, and the amount of heat generated tends to increase. Therefore, from the heat dissipation surface of the package, there is an increasing demand for structures and materials having excellent heat dissipation. Is coming. A ceramic package is known as a highly heat-dissipating package that satisfies such requirements, and expectations for a BGA package made of this ceramic package are increasing.

That is, the BGA package made of ceramics is a high-density package satisfying high heat dissipation and excellent electrical characteristics, capable of multi-terminals and narrow pitch, and is a semiconductor device with high speed and high integration. Is expected as a package for. A ceramic BGA package is usually manufactured by using a ceramic multilayer wiring board as a package base and joining a solder ball on the electrode pad provided on the surface of the package base with a low melting point solder.

[0006]

However, when the ceramic BGA package is mounted on a printed circuit board or the like, the difference in the coefficient of thermal expansion between the ceramic package base and the printed circuit board is large. However, there is a problem in that the reliability of the solder ball (bump) portion is likely to decrease.

That is, since the coefficient of thermal expansion of a ceramic material is generally on the order of 10 ^-6 / K and that of a resin material is on the order of 10 ^-5 / K, reflow soldering when mounting a ceramic BGA package on a printed circuit board is performed. The stress generated by the heat history received in the attaching step, the heat history caused by the environmental temperature change during normal use, and the like are directly applied to the bonding interface between the solder ball and the electrode pad having the weakest mechanical strength. This causes a decrease in bonding strength, an increase in connection resistance, etc., leading to a decrease in reliability of the connection portion. For this reason, there is a demand for a terminal structure that is highly reliable with respect to heat history and the like.

On the other hand, a multilayer ceramic substrate having a recess formed in the electrode pad portion into which a connection terminal formed on the printed circuit board side is inserted is disclosed in Japanese Patent Application Laid-Open No. 60-94794 and a ceramic layer having a positioning hole for input / output pins. Special advantage of multi-layer ceramics substrate with (dummy layer) on electrode pad 7-6
It is described in Japanese Patent No. 0936. However, in any of the methods for manufacturing a multilayer ceramic substrate described in these publications, a green sheet for a dummy layer and a green sheet constituting the main body of the multilayer ceramic substrate are laminated and pressure-bonded, and the green sheet pressure-bonded body is collectively packaged. Since this is a firing method, it has the following problems.

That is, in the above-described collective firing method, the shape of the recess and the material of the recess forming layer are limited. Also,
Due to the pressure applied when the green sheets are stacked and pressure-bonded, there is a problem that the shapes of the terminal insertion recesses and the input / output pin positioning holes formed on the green sheets are practically lost.

On the other hand, if the pressure at the time of pressure bonding is adjusted, the reliability of the multilayer ceramic substrate itself will be impaired. Even if this decrease in reliability is removed, as shown in FIG. 6, the obtained recessed portion 1 has a shape in which the inner wall surface is raised (θ = 90 degrees).
2 is a dummy ceramic layer. As described in Japanese Patent Publication No. 7-60936, the recess 1 having such a shape is not a problem when used as a positioning hole for a pin, but the solder ball 3 is provided in the recess 1. If the solder balls 3 are arranged, the contact between the recesses 1 and the solder balls 3 is point contact, so that the thermal stress is concentrated and the solder balls 3 are likely to be cracked or the like. Further, depending on the diameter of the concave portion 1, there is a possibility that the connection between the solder ball 3 and the electrode pad 4 may be defective.

Thus, the conventional ceramic BGA
In the package, a terminal portion structure having excellent reliability with respect to heat history and the like is required, but a thermal stress relaxation / suppression structure suitable for a solder ball or the like has not been found. For this reason, it is an object to stably alleviate and suppress the concentration of thermal stress on the solder balls and the like.

Further, in the above-mentioned conventional method, since the recess is formed by co-firing using a green sheet, the package is used when the recess is unnecessary (LGA package etc.) or when the size of the recess is desired to be changed. It had to be recreated and had the problem of low versatility.

The present invention has been made to solve such a problem, and when a conductive ball such as a solder ball is used as an external connection terminal, it has an effect of mitigating / suppressing stress concentration on the conductive ball. A method for manufacturing a semiconductor package base body, which is capable of stably obtaining an excellent concave portion, and has improved selectivity of the concave portion shape and the material of the concave portion forming layer,
Furthermore, the present invention provides a method for manufacturing a semiconductor package base body, which allows a recess to be formed in a post-process in a baked package substrate by selecting the material of the recess forming layer, thereby increasing the degree of freedom with respect to the size of the recess. It is an object.

[0014]

A method of manufacturing a semiconductor package substrate according to the present invention is a method of manufacturing a baked package having an electrode pad formed on a main surface and an internal wiring layer electrically connected to the electrode pad. Alternatively, a step of producing an unfired ceramic wiring substrate, and an insulating paste so that at least a part of the electrode pad surface is exposed on the electrode pad forming surface of the ceramic wiring substrate and rises from the electrode pad surface. And a step of curing the coating layer of the insulating paste to form an insulating layer having a concave portion for installing a conductive ball that functions as an external connection terminal. In the method for manufacturing a semiconductor package substrate of the present invention, the insulating layer having the recesses for setting the conductive balls is formed by applying and curing an insulating paste. When the insulating layer is formed by applying and curing the insulating paste, the opening end surface of the insulating layer has an angle, and thus the inner wall surface of the conductive ball setting recess can be tapered. Therefore, the conductive balls can be supported by the tapered inner wall surface of the recess. That is, the conductive ball and the recess can be brought into surface contact with each other. As a result, when thermal stress is generated due to thermal history, etc., local stress concentration at the bonding interface between the conductive ball and the electrode pad can be relaxed / suppressed, and the reliability of the connection part can be improved. It will be possible. In addition, it is possible to increase the degree of freedom in the shape of the recess and the material of the insulating layer for forming the recess.

In this case, when a ceramic paste is used as the insulating paste, the ceramic paste is applied to an unfired ceramic wiring board, and these are simultaneously fired and cured. Further, when the resin paste is used as the insulating paste, the resin paste is applied to the fired ceramics wiring board, and heat treatment is applied to cure it. When a resin paste is used, the degree of freedom of the size and shape of the recess becomes higher.

[0016]

Embodiments of the present invention will be described below.

FIG. 1 is a diagram showing a BGA package substrate manufactured by applying one embodiment of the method for manufacturing a semiconductor package substrate of the present invention.

BGA package substrate 10 shown in FIG.
Is a ceramics multilayer substrate 11 in which ceramics layers 11a, 11a, which are insulating layers, are multilayer-integrated, inner layer wirings 12 provided in the ceramics multilayer substrate 11, and electrically connected to the inner layer wirings 12. First and second provided on both main surfaces of the multilayer substrate 11, respectively
The ceramic multilayer wiring board 15 having the electrode pads 13 and 14 of FIG.

The material of the ceramic multilayer wiring board 15 is not particularly limited, and various ceramic materials such as alumina, aluminum nitride, silicon nitride and the like can be applied. Particularly, as with aluminum nitride, a package is used. The present invention is particularly effective when the difference in the coefficient of thermal expansion from the resin board such as the printed circuit board to be mounted is large. Specifically, the present invention is particularly effective when the difference in coefficient of thermal expansion between the ceramic multilayer wiring board 15 and the printed circuit board or the like is 5 × 10 ⁻⁶ / K or more.

The inner layer wiring 12 is the ceramic multilayer substrate 1
1 is composed of a via hole 16 formed by filling a through hole provided in each ceramic layer 11a, 11a ... With a conductive material, and a conductor element 17 formed by printing on the internal ceramic layer 11a, 11a. ing.
The inner layer wiring 12 is formed in accordance with a desired signal wiring pattern or the like, and the first electrode pad 13 and the second electrode pad 1 formed on the front surface side of the ceramic multilayer substrate 11 are formed.
4 is electrically connected.

The above-mentioned first and second electrode pads 1
3, 14, the via hole 16, and the conductor element 17 are
Both are formed by co-firing with the ceramic multilayer substrate 11. That is, first, through holes are formed in the ceramic green sheets corresponding to the respective ceramic layers 11a, 11a ... And the conductive paste mainly composed of a high melting point metal such as W or Mo is filled in the through holes, and at the same time, the conductor element 17 is formed. A conductor paste is printed on the ceramic green sheet according to the shapes of the first and second electrode pads 13 and 14. After laminating and pressing the required number of ceramic green sheets like this,
It is obtained by degreasing and firing this green sheet pressure-bonded body, and simultaneously sintering the ceramic base material and the conductor. At this time, when the insulating layer 19 which will be a recess forming layer described later is formed using a ceramic paste, the ceramic paste is applied to the unfired ceramic multilayer wiring substrate 15, that is, the green sheet pressure-bonded body,
After that, degreasing and firing are performed to simultaneously sinter the ceramic base material, the conductor, and the ceramic paste.

The first electrode pad 13 functions as an electrical connection terminal to the semiconductor element, that is, an internal connection terminal, while the second electrode pad 14 is formed on the external electrode pad described later in detail. A conductive ball, such as a solder ball, which functions as a connection terminal for use is joined.

Then, as shown in the enlarged view of FIG. 2, at least a part of the surface of the second electrode pad 14 is exposed on the formation surface of the second electrode pad 14 to which the solder balls and the like are joined. The insulating layer 19 having the concave portions 18 is formed of an insulating paste, and the BGA package substrate 10 is formed of these. The recessed portion 18 provided in the insulating layer 19 serves as an installation portion for a conductive ball such as a solder ball that constitutes a bump terminal, and its inner wall surface 1
8a is tapered with an angle θ.

The BGA package substrate 10 described above is
It is manufactured as follows. A manufacturing process of the BGA package substrate 10 will be described with reference to FIG.

That is, as shown in FIG. 3A, first, for example, an unfired ceramic multilayer wiring board 15 'is manufactured by a usual method, that is, by laminating the above-mentioned ceramic green sheets. Note that FIG. 3A illustrates the second electrode pad 14 with the surface on which the second electrode pad 14 is formed facing upward.

Next, the insulating paste 20 made of a ceramic paste is formed on the surface on which the second electrode pad 14 is formed.
Is applied so that at least part of the surface 14a of the second electrode pad 14 is exposed and rises from the surface 14a of the second electrode pad (FIG. 3 (b)). After that, the ceramic base material, the conductor, and the ceramic paste are simultaneously sintered to form the conductive ball placement recesses 18
The insulating layer 19 having the
At the same time, it is manufactured (FIG. 3C).

Examples of the above-mentioned ceramic paste include those prepared by mixing ceramic powders of the same type or different types as the ceramic multilayer substrate 11 with an organic binder and an organic solvent to form a slurry. It is also possible to use a ceramic powder different from that of the ceramic multilayer substrate 11, but in order to prevent cracking due to a difference in shrinkage rate that occurs during firing, it is preferable to use a ceramic powder of the same material as the ceramic multilayer substrate 11. preferable.

When a resin paste whose curing temperature is much lower than the sintering temperature of the ceramics is used as the insulating paste 20, after the resin paste is applied to the fired ceramics multilayer wiring board 15. Then, the insulating layer 19 is formed by being cured by heat treatment. As the resin paste, for example, a resin varnish or a resin paste for application / curing containing epoxy resin, silicone resin, polyamide resin, polyimide resin or the like as a main material can be used. Among these, it is preferable to use a polyimide resin, an epoxy resin, a silicone resin, or the like, which is particularly excellent in heat resistance.

The insulating paste 20 is applied by, for example, screen printing using a screen or the like according to the formation pattern of the second electrode pad 14. At this time, since the opening end face is angled as a feature of the application of the insulating paste 20, the angle θ ′ can be satisfactorily applied to the applied end portion 20 ′ of the insulating paste 20. This angle θ ′ can be adjusted by the viscosity of the insulating paste 20 and the taper angle of the opening of the screen used for printing.

The insulating paste 20 is applied such that the thickness of the insulating layer 19 after curing or sintering is 30 μm or more from the surface of the second electrode pad 14a, and 10% or more of the diameter of the conductive ball to be installed. It is preferable to set so as to satisfy at least one of the above. When the thickness of the insulating layer 19 is less than 30 μm from the surface of the second electrode pad 14a or less than 10% of the diameter of the conductive ball to be installed, it is difficult to bring the conductive ball and the recess 18 into good contact with each other. Become. The insulating paste 20 is applied so that the thickness of the insulating layer 19 after curing or sintering is 100 from the surface of the second electrode pad 14a.
It is more preferable to set so as to satisfy at least one of μm or more and 15% or more of the diameter of the conductive balls to be installed.

The conductive ball installation recess 18 thus obtained has a taper formed on the inner wall surface 18a thereof at an angle θ substantially equal to the angle θ ′ given to the coating end 20 'of the insulating paste 20. It The formation angle θ of the inner wall surface 18a of the recess is preferably in the range of 30 to 80 degrees. When the angle θ is less than 30 degrees or more than 80 degrees, the surface contact property between the inner wall surface 18a and the conductive balls may be deteriorated and the strength of the contact portion may be decreased. Angle θ
Is more preferably in the range of 35 to 75 degrees. When the insulating layer 19 having the recesses 18 for setting the conductive balls is formed by coating and curing the insulating paste 20 separately from the ceramic multilayer wiring board 15, not only the insulating resin material but also the ceramic multilayer board 11 is formed. Can be selected from different materials such as different ceramic materials can be used. Further, the shape (opening diameter, depth, angle) of the conductive ball installation recess 18 can be appropriately changed without changing the ceramic multilayer substrate 11. As described above, by increasing the selectivity of the material for forming the insulating layer 19 and the shape of the recesses 18 for setting the conductive balls, it becomes possible to easily deal with various conductive balls.

B obtained by the above manufacturing method
As shown in FIG. 4, in the GA package substrate 10, conductive balls 21 made of solder balls, conductive resin balls, or the like are arranged in the recesses 18 for setting the conductive balls, and the conductive balls 21 and the electrode pads 14 are arranged. It is used as the BGA package 22 by joining the inner wall surface 18a and the recess inner wall surface 18a through a low melting point solder paste or the like (not shown).

At this time, since the angle .theta. Is given to the inner wall surface 18a of the recess 18 for installing the conductive ball, not only is the installability of the conductive ball 21 excellent, but also the conductive ball 2 is provided.
The conductive balls 21 can be installed in the conductive ball installation recesses 18 in a state where the surface 1 and the recess inner wall surface 18a are in surface contact with each other. As a result, it is possible to reliably realize a structure in which the conductive balls 21 are supported laterally, that is, in the direction in which thermal stress is applied.

The BGA package 22 constructed by joining the conductive balls 21 as described above is used as a package component as follows. That is, for example, as shown in FIG. 5, the semiconductor element 23 is mounted on the front surface side of the BGA package 22, and the electrode pad 13 and the electrode of the semiconductor element 23 are electrically connected by the bonding wire 24, for example. Furthermore, by hermetically sealing the semiconductor element 23 with a ceramic cap 25 or the like,
A package component 26 is obtained.

Then, such a package component 26
Is used as a mounting module 28 by mounting it on a printed circuit board 27 of glass epoxy type or the like.
The mounting on the printed board 27 is performed by, for example, the printed board 2 facing the conductive balls 21 on the package component 26 side.
After printing the solder paste on the terminals 27a of No. 7, the package component 26 may be placed and reflowed.

The mounting module 28 having the above-mentioned configuration
In the above, even if thermal stress is generated due to the difference in thermal expansion between the ceramic BGA package 22 and the printed circuit board 27 on which it is mounted, the conductive balls 21 can be inserted into the recess inner wall surface 1
Since it is supported laterally by 8a, the surface contact portion bears stress. That is, it is possible to avoid concentration of stress on the bonding interface between the electrode pad 14 and the conductive ball 21, and the structure is such that the conductive ball 21 as a whole is superior in mechanical strength as compared with this bonding interface to support thermal stress. Since it is possible to suppress local stress concentration, it is possible to significantly increase the reliability of the conductive balls 21 with respect to the thermal history of the connection portion.

[0037]

Next, specific examples of the present invention will be described.

Example 1 First, Al was used as a constituent material of the ceramic multilayer substrate 11.
Using N as the conductive material and W as the conductive material, an unfired ceramic multilayer wiring substrate 15 'was produced. On the surface of the unfired ceramic multilayer wiring substrate 15 'on which the second electrode pad 14 is formed, an AlN insulating paste prepared by mixing AlN powder with an organic binder to form a slurry is printed to form a coating layer, followed by degreasing. Then, the ceramic multilayer wiring board 15 and the AlN insulating layer 19 were fired to form the same by simultaneous sintering. Then, the surface of the electrode pad 14 was plated to form an electrode. The thickness of the AlN insulating layer 19 is 50 μm, and the angle θ of the inner wall surface 18a of the recess 18 for setting the conductive ball is about
It was 50 degrees.

On the electrode pad 14 of the BGA package substrate 10 thus manufactured, that is, in the recess 18 for setting the conductive ball, the solder ball 21 having a composition of Sn10 wt% -Pb90 wt% is arranged and the solder ball is formed. 21 and the electrode pad 14 and the inner wall surface 18a of the recess were joined using a low melting point solder paste having a composition of Sn60 wt% -Pb40 wt%. Next, using this BGA package 22,
After making the package component 26 as shown in FIG.
It was mounted on the glass epoxy printed board 27 using a low melting point solder paste. When the characteristics of the thus obtained mounting module 28 were evaluated by a thermal cycle test, more reliable results could be obtained as compared with the package in which the AlN insulating layer was not formed.

Example 2 On the surface of the fired ceramic multilayer wiring substrate 15 having the same structure as in Example 1 on which the second electrode pad 14 is formed,
The polyimide resin insulating layer 19 was formed as follows. That is, after plating the surface of the electrode pad 14, spin coating photosensitive polyimide, exposing and developing to form a concave portion exposing a part of the electrode surface, and then 623K
Cured at the temperature of.

On the electrode pad 14 of the BGA package substrate 10 thus manufactured, that is, in the recess 18 for setting the conductive ball, Sn 10 wt% -P was added in the same manner as in Example 1.
Solder balls 21 having a composition of 90% by weight b were set (joined), and a package component 26 was produced in the same manner, and then mounted on a glass epoxy printed board 27 using a low melting point solder paste. The thus obtained mounting module 28 showed good reliability as in the first embodiment.

[0042]

As described above, according to the method of manufacturing a semiconductor package substrate of the present invention, when conductive balls such as solder balls are used as external connection terminals, stress concentration on the conductive balls is relaxed. -It is possible to stably obtain a recess having an excellent suppressing effect. In addition, the selectivity of the recess shape, the material of the recess forming layer, and the like can be significantly increased.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a BGA package substrate manufactured by applying an embodiment of a method for manufacturing a semiconductor package substrate of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a main part of the BGA package substrate shown in FIG.

FIG. 3 is a cross-sectional view showing a main part manufacturing process of the BGA package base body shown in FIG. 1;

4 is a cross-sectional view showing a state where conductive balls are bonded to the BGA package substrate shown in FIG.

5 is a cross-sectional view showing a package component manufactured using the BGA package base body shown in FIG. 1 and a state in which the package component is mounted on a printed circuit board.

FIG. 6 is an enlarged sectional view showing a state in which a solder ball is installed in a package having a conventional structure.

[Explanation of symbols]

 10 ... Base for BGA package 12 ... Internal wiring layer 13, 14 ... Electrode pad 15 ... Ceramic multilayer wiring board 18 ... Recess for setting conductive balls 19 ... Insulation layer 20 ... Insulation paste 21 ... Conductivity Sex balls

Claims (5)

[Claims] 1. A step of producing a fired or unfired ceramic wiring substrate having an electrode pad formed on a main surface and an internal wiring layer electrically connected to the electrode pad, and the ceramic wiring. On the electrode pad forming surface of the substrate, exposing at least a part of the electrode pad surface, and so as to rise from the electrode pad surface, a step of applying an insulating paste, and curing the application layer of the insulating paste, And a step of forming an insulating layer having a recess for setting a conductive ball that functions as an external connection terminal. 2. The method for manufacturing a semiconductor package substrate according to claim 1, wherein an angle of 30 to 80 degrees is given to an inner wall surface of the conductive ball mounting recess. Method. 3. The method for manufacturing a semiconductor package substrate according to claim 1, wherein the thickness of the insulating layer having the recesses for installing the conductive balls is 30 μm or more from the surface of the electrode pad, or A method of manufacturing a package base for semiconductors, characterized in that the diameter of the conductive balls is 10% or more. 4. The method for manufacturing a semiconductor package substrate according to claim 1, wherein a ceramic paste is used as the insulating paste, the ceramic paste is applied to the unfired ceramic wiring substrate, and these are simultaneously fired. A method of manufacturing a semiconductor package substrate, which comprises curing. 5. The method of manufacturing a semiconductor package substrate according to claim 1, wherein a resin paste is used as the insulating paste, and the resin paste is applied to the fired ceramics wiring board and heat-treated to be cured. A method of manufacturing a characteristic package base for a semiconductor.