JP2002043368A - Electric circuit device and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer printed board capable of preventing the boundary breakage of an electrode and BGA at the time of mounting the BGA on the electrode of the multilayer printed board, realizing high reliability and facilitating the repair of the BGA, and to provide a mounting method and a mounting structure body using it. SOLUTION: The surface electrode 8 of the multilayer printed board 1 is formed, being recessed from the surface of the multilayer printed board 1 to a center part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure of a multilayer printed circuit board on which a ball grid array is mounted, an electric circuit device using the multilayer printed circuit board, and a method of manufacturing the same.

[0002]

2. Description of the Related Art LSI packages used in personal computers and various devices for performing high-speed digital data processing include:
Increasing the number of pins and speeding up are progressing. Therefore, the conventional Q
The FP (quad flat package) type is shifting to a ball grid array (hereinafter referred to as BGA).

A mounting structure using this BGA is, for example,
FIG. 13 shows a structure as shown in a sectional view in which a BGA is mounted on a multilayer printed circuit board.

The BGA 102 has a spherical solder ball electrode 107 (sometimes simply referred to as a solder ball) on the lower surface of a semiconductor element. Multilayer printed circuit board 10
Numeral 1 denotes a structure in which conductor layers 103 and insulating layers 104 are alternately stacked from the lower layer. The lower conductor layer 103 and the upper conductor layer 1
03 is connected by a through-hole via 105 which is also a conductor layer. The conductor layer 103 is formed as a wiring or an electrode mainly by copper plating. The conductor layer 103 located on the surface of the multilayer printed board 101
The conductor layer 103 used for soldering with the electronic component 02 and other electronic components is particularly called an electrode.

The electrode 103 (conductor layer) is provided in parallel with the multilayer printed board 101, and the other conductor layer 103 (ie, wiring) located on the surface of the multilayer printed board 101 is coated with a solder resist 106. To prevent disconnection and short circuit of the wiring.

The electrode 10 on the multilayer printed circuit board 101
3, the spherical solder ball electrode 107 of the BGA 102 is positioned and mounted, and is exposed to a high-temperature atmosphere using a reflow furnace or the like, so that the spherical solder ball electrode 107 of the BGA 102 is melted and multilayer printed. It is bonded to the electrode 103 (wiring) on the substrate 101.

[0007]

However, the above-described technology has the following problems. That is,
When the multilayer printed circuit board 101 on which the BGA 102 is mounted is repeatedly energized and cut, or exposed to an environment where the temperature changes drastically, the BGA 102 and the multilayer printed circuit board 101 repeat thermal expansion and thermal contraction.

FIG. 1 shows the thermal expansion and thermal contraction at that time.
As shown in FIG. 3, arrow A (arrow 108) points to BGA1
02 indicates the magnitude and direction of thermal expansion and thermal contraction, while arrow B indicates the magnitude and direction of thermal expansion and thermal contraction of the multilayer printed circuit board 101. That is, the multilayer printed circuit board 1
01 has a tendency to be generally larger than the BGA 102 in thermal expansion and thermal contraction.

FIG. 14 is an enlarged view of the periphery of one of the spherical solder ball electrodes of FIG. Arrow C corresponds to FIG.
3 shows a difference in thermal expansion between the BGA 102 and the multilayer printed board 101 shown in FIG.
It expands and contracts outside the center of BGA 102 with respect to A 102. While repeating this, the multilayer printed circuit board 101
When a crack 111 is formed at a joint end (intersecting line) between the upper electrode 103 and the spherical solder ball electrode 107 of the BGA 102, the electrode 103 and the BGA eventually break, causing an open defect. There was a problem.

[0010] In recent years, the pitch of the spherical solder ball electrodes of BGA tends to be as narrow as 0.5 mm or less, so that the bonding area of the spherical solder ball electrodes tends to be further reduced, and open defects are reduced. It is expected to occur frequently.

In addition, many of the central processing units and the like used in notebook type personal computers are mounted in high density in the form of BGA, and the performance thereof is improving every few months. Therefore, even if it is attempted to replace the central processing unit with a higher performance, the BG used in the central processing unit
Since A is mounted at a high density, it is difficult to remove and replace it.

The present invention has been made in view of these circumstances. Therefore, when mounting a BGA on an electrode of a multilayer printed circuit board, it is possible to prevent interface breakage between the electrode and the BGA to realize high reliability. An object of the present invention is to provide an electric circuit device capable of easily repairing a BGA and a method of manufacturing the same.

[0013]

According to the first aspect of the present invention, there is provided an electric circuit device having a wiring substrate having electrodes and a semiconductor element arranged to be electrically connected via bumps. An electric circuit device, wherein the surface of the electrode is obliquely formed with respect to an imaginary plane including a line of intersection between the surface of the bump and the surface of the electrode.

According to the second aspect of the present invention,
In an electric circuit device having a wiring board having electrodes and a semiconductor element arranged to be electrically connected via bumps, at least a joint end formed by the surface of the electrodes and the surface of the bumps An electric circuit device, wherein a surface of the electrode is oblique to a virtual plane including a boundary line to be formed.

According to the third aspect of the present invention,
The electric circuit device is characterized in that the electrode is an electrode having a concave surface with respect to the main surface of the wiring board, and the bump is arranged to cover the concave shape.

According to the means of the invention of claim 4,
A bump is arranged on an electrode provided on the surface of the wiring substrate, and the bump and the electrode are joined by heating the bump, and a crossing line formed between the surface of the bump and the surface of the electrode is included. A method for manufacturing an electric circuit device, comprising a step of configuring the surface of the electrode to be oblique to a virtual plane.

According to the fifth aspect of the present invention,
Placing an electrical component having a bump on an electrode provided on the surface of the wiring board, holding the bump and the electrode by pressing and holding the electrical component against the wiring board, A method for manufacturing an electric circuit device, comprising a step of configuring the surface of the electrode so as to obliquely intersect with a virtual plane including a line of intersection between the surface of the bump and the surface of the electrode.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The mounting method of the present invention and the structure of the mounting structure will be described below with reference to the drawings.

FIG. 1 shows a multilayer printed circuit board and a BGA according to the present invention.
FIG. 3 is a side cross-sectional view of the structure of FIG. 1 when a BGA is aligned and mounted on a multilayer printed circuit board.

The multilayer printed circuit board 1 is made of epoxy resin, and is formed by alternately laminating wirings 3 as conductor layers and insulating layers 4 from the lower layer. The lower wiring 3 and the upper wiring 3 are made of a conductor. Are connected by through-hole vias 5. On the surface of the multilayer printed board 1, a spherical solder ball electrode 7 as a bump formed on the multilayer printed board 1 side of the BGA 2 and a surface electrode 8 provided for solder bonding are formed. I have.

The surface electrode 8 is provided on the inside of the multilayer printed board 1 with the surface of the ball electrode 7 as a bump and the surface electrode 8.
Surface electrode 8 with respect to an imaginary plane including the line of intersection of
Are formed obliquely. That is, the surface electrode 8
Forms a tapered conical surface with respect to the center of the multilayer printed circuit board 1. Therefore, the multilayer printed circuit board 1 does not have a plane parallel to the center plane. This conical surface is BGA
2 and is connected to the solder ball electrode 7.

The multi-layer printed circuit board 1 at other locations
The wiring 3, which is a conductor layer formed on the surface of the wiring 3, is formed parallel to the bottom surface of the multilayer printed circuit board 1 and is coated with a solder resist 6 to prevent the wiring 3 from being disconnected or short-circuited. In addition, the wiring 3 and the surface electrode 8
It is mainly formed by copper plating.

The BGA 2 has a semiconductor element 32 mounted on a BGA substrate 31 and an electrode 33 on the semiconductor element 32 is
It is joined to the surface side electrode 34 of the A substrate 31 by the gold wire 35. The front-side electrode 34 of the BGA substrate 31 is joined to the back-side electrode 37 via a through-hole via 36, and the back-side electrode 37 is provided with the solder ball electrode 7.

The back surface electrode 37 to which the solder ball electrode 7 is joined is formed thinner than the solder resist 37 'to which the solder ball electrode 7 is not joined. The semiconductor element 37 is sealed with a sealing material 38 such as an epoxy resin.

With these configurations, as shown in FIG. 2, a spherical solder ball electrode 7 of the BGA 2 is aligned with the surface electrode 8 on the multilayer printed circuit board 1 by a mounting apparatus (not shown), and then closely contacted. Let it be mounted.

In the above-described embodiment, the structure of the solder resist 6 is a clearance structure as shown in FIG. 1, that is, a structure formed on the multilayer printed circuit board 1 (for bonding with a solder ball electrode of BGA). 3) The solder resist 6 is formed so as not to cover the surface electrode 8. The solder resist has an over-resist structure as shown in FIG. 3, that is, the surface formed on the multilayer printed circuit board 1. The solder resist 6 ′ may be formed so as to partially cover the electrode 8. In this case, the shape after the joining is as shown in FIG. In FIGS. 3 and 4, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and their description is omitted.

Although the epoxy resin is used for the insulating layer 4 of the multilayer printed board 1, a phenol resin or the like can be used as appropriate. Further, although electroless copper plating is used as the wiring 3 of the conductor layer, electrolytic copper plating, gold sputtering, or the like can be used as appropriate.

Next, as shown in FIG. 5, the multilayer printed circuit board 1 on which the BGA 2 shown in FIGS. 1 and 2 is mounted is exposed to a high-temperature atmosphere using a reflow furnace (not shown) or the like. Thereby, the solder ball electrode 7 formed on the BGA 2
Is melted, and the conical surface electrode 8 on the multilayer printed circuit board 1 is melted.
The inner wall is filled closely. Then, after a predetermined time has passed at room temperature, the solder ball electrode 7 and the surface electrode 8
Are fixedly joined to form a mounting structure.

FIG. 6 shows one of the spherical solder ball electrodes 7 when the multi-layer printed circuit board 1 on which the BGA 2 is mounted is repeatedly subjected to energization and cutting, or exposed to an environment where temperature changes drastically. It is the enlarged view which expanded typically.
The same parts as those in FIG. 2 are denoted by the same reference numerals, and their description is omitted.

An arrow 10 indicates a vector of a difference in thermal expansion between the BGA 2 and the multilayer printed circuit board 1. The multilayer printed board 1 expands and contracts with respect to the BGA 2 outside the center of the BGA 2. That is, thermal stress occurs in the direction of arrow 10.
However, the shearing direction of the bonding interface between the solder ball electrode 7 of the BGA 2 and the surface electrode 8 on the multilayer printed board 1 is not parallel to the direction 10 of the thermal stress, as indicated by the arrow 11. Therefore, the electrode 3 on the multilayer printed circuit board 1 and the BGA
2 has an effect of preventing a crack from being easily formed in the interface with the solder ball electrode 7 and preventing the interface from being broken.

Next, a method of manufacturing a multilayer printed board according to the present invention will be described.

FIG. 7 is a schematic view showing an outline of a method of manufacturing a through-hole via of a multilayer printed circuit board.

First, the multilayer printed circuit board 1 is formed by forming a resist film (not shown) on the insulating layer 4 such as an epoxy resin from the lower layer.
To a thickness of about 0.018 by electroless copper plating.
After forming a wiring 3 of a conductor layer having a thickness of 2 mm and removing the resist film, an insulating layer 4 having a thickness of about 0.06 mm is laminated thereon. This is repeated several times to form portions other than the outermost layer. The lower wiring 3 and the upper wiring 3 have a diameter of about φ0.15.
By forming the through-hole via 5 mm, electrical continuity is obtained.

The through-hole via 5 is formed by making a hole from the upper wiring 3 to the insulating layer 4 and penetrating the lower conductive layer wiring 3 by a laser processing device or the like, and forming a conductive layer on the inner wall of the through hole by fine plating. I have.

It should be noted that the laser processing apparatus uses a laser oscillator 1
2 is guided by an optical system formed by a pattern mask 14 for adjusting a hole shape, a prism 15 (or a reflecting mirror), a focus lens 16 moving up and down, and the like. By irradiating a predetermined portion, a predetermined through hole is formed in the insulating layer 4.

In forming the through-hole vias 5 on the multilayer printed circuit board 1, a similar uniform shape can be obtained by machining with a drill or the like without using a laser machining apparatus. Can be used.

FIG. 8 is an explanatory diagram of the range of the cross-sectional shape of the surface electrode formed on the surface of the multilayer printed circuit board. In addition, each parameter is defined as follows.

Radius of spherical solder ball electrode: R Thickness of insulating layer: Z Diameter of outermost layer of conical hole formed by laser: H Center of solder ball electrode from apex of conical hole formed by laser Distance to: L Angle between the center line passing through the center of the conical hole formed by the laser and the surface of the hole: α Pitch of solder ball electrode: P Minimum spacing of the insulating layer between wirings on the outermost layer :
S Next, a range of an appropriate cross-sectional shape is obtained using these.

First, tan α = (H / 2) / Z (1)
Is established.

Further, the relationship of sin α = R / L (2) is established.

Therefore, the range of the angle (α) between the center line passing through the center of the conical hole formed by the laser and the surface of the hole is obtained. Assuming that the maximum value of the diameter of the outermost layer of the conical hole formed by the laser is Hmax, the relationship of H ≦ Hmax = PS (3) holds. Let αmax be the maximum value of α, (3)
Is substituted into (1), and tanα ≦ tanαmax = (H
max / 2) / Z... (4) By solving (4), the maximum value of α (αmax) is obtained.

Α ≦ αmax (5) On the other hand, since the spherical solder ball electrode 7 must be in contact with the surface electrode 8 on the multilayer printed circuit board 1, L ≦ αmax
It is necessary to satisfy the relationship of R + Z (6). From (2), L = R / sin α (7) can be deformed. When the minimum angle is αmin, L = R / sinα ≦ R / sinα
min = R + Z (8)

By transforming (8), sinαmin = R
/ (R + Z) (9) is obtained. By solving (9), the minimum value of α (αmin) is obtained.

Αmin ≦ α (10) From (5) and (10), αmin ≦ α ≦ αmax (1
1) is obtained.

Next, as a specific example, when calculation is performed using specific numerical values, for example, in the case of the following values, α is obtained.

R = 0.15 mm Z = 0.1 mm H = 0.3 mm P = 0.5 mm S = 0.075 mm From (3), Hmax = 0.5 mm−0.075 mm =
0.425 mm From (4), tan αmax = (0.425 mm / 2)
/0.1mm Therefore, αmax = 64.8 °.

According to (9), sinαmin = 0.15 m
m / (0.15 mm + 0.1 mm) Therefore, αmin = 36.9 °.

Therefore, α is 36.9 ° ≦ α ≦ 64.8 °
.. May be formed in the range of (10).

In the case of the above specific example, tan α =
(0.3 mm / 2) /0.1 mm Therefore, α = 56.3 °. This satisfies (10), and the shape of the hole formed by irradiation can be in contact with the solder ball electrode.

In the above case, Z is defined as the thickness of the insulating layer. However, as shown in FIG. 9, the shape of the surface electrode 8a on the multilayer printed circuit board 1a is
a and a through-hole via 5a which is a conductor layer for connecting to the lower electrode 3a. In FIG. 9, the same parts as those in FIG.

At this time, as the values of Z and L, the values of the parts shown as distance Z 'and distance L' in FIG. 10 are used.

FIGS. 11A to 11D are schematic views showing a manufacturing process of the outermost layer portion of the above-mentioned multilayer printed circuit board. The same parts as those in FIG. 7 are denoted by the same reference numerals, and the description thereof will not be repeated.

In this example, since the additive method is used, a multi-layer printed circuit board in which a conical recess is formed at a predetermined portion of the outermost layer shown in FIG. 7 as shown in FIG. 1, a resist film 17 (plating resist) is formed.

Next, as shown in FIG. 11 (b), the multilayer printed circuit board 1 on which the resist film 17 is formed is subjected to electroless copper plating to form a surface electrode for bonding to the solder ball electrode 7 of the BGA 2. 8 and through-hole vias 5 are formed.

Next, as shown in FIG. 11C, the resist film 17 is removed from the surface of the multilayer printed board 1 with a solvent.

Further, as shown in FIG. 11D, a solder resist 6 is formed on the multilayer printed circuit board 1.

Through these steps, a multilayer printed circuit board having the electrode configuration of the present invention can be manufactured.

The subtractive method can be used instead of the additive method as described above.

Next, an application example of the mounting structure of the present invention will be described.

FIG. 12 is a side sectional view of an application example of the mounting structure of the present invention. 1 are denoted by the same reference numerals as in FIG.

In this case, the surface electrode 8c of the multilayer printed circuit board 1c and the solder ball electrode 7c of the BGA 2c are connected and fixed by the pressing force of the fixing tool without using the connection by melting the solder.

Surface electrode 8c on multilayer printed circuit board 1c
And a spherical solder ball electrode 7 formed on the BGA 2c.
c is aligned and mounted. A heat transfer sheet 19 having a thickness of about 2 mm in which metal particles are mixed in a silicone resin is placed on the BGA 2c, and the heat transfer sheet 19 is pressed from above with a fixing tool 20 made of magnesium.
Are fixed with the fixing screw 18.

Thus, the solder ball electrode 7c of the BGA 2c and the surface electrode 8c of the multilayer printed circuit board 1c are pressed and connected in close contact with each other, so that electrical continuity is obtained. In addition, since it is fixed integrally with the heat sink via the heat transfer material, a good heat radiation effect can be obtained.

Further, since the fixing means is fastening by the fixing screw 18, by loosening or tightening the fixing screw 18, the attachment / detachment of the BGA 2c becomes easy, and a defective product can be replaced as needed.

Although magnesium is used as the material of the fixture 20, an aluminum alloy or the like can be used as appropriate. Further, as the heat transfer sheet 19, a material in which metal particles are mixed in a silicon resin is used, but natural rubber or an elastomer in which metal powder, carbon, or the like is mixed may be used as appropriate.

[0066]

According to the present invention, high mounting reliability can be obtained when mounting a BGA on a multilayer printed circuit board.

Further, simplification of BGA replacement can be realized.

[Brief description of the drawings]

FIG. 1 is a side sectional view when a BGA is to be mounted on a multilayer printed board according to the present invention.

FIG. 2 is a side cross-sectional view around a solder ball electrode during bonding.

FIG. 3 is a side sectional view showing a modification of FIG. 1;

FIG. 4 is a side sectional view of the vicinity of a solder ball electrode at the time of joining in FIG. 3;

FIG. 5 is a side sectional view of a mounting structure in which a BGA is mounted on a multilayer printed board according to the present invention.

FIG. 6 is an explanatory diagram of stress applied to a solder ball electrode after joining.

FIG. 7 is a schematic view showing an outline of a method of manufacturing a through-hole via of a multilayer printed circuit board.

FIG. 8 is an explanatory diagram of a range of a cross-sectional shape of a surface electrode formed on a surface of a multilayer printed circuit board.

FIG. 9 is a side sectional view of an application example in which a BGA is mounted on a multilayer printed board according to the present invention.

FIG. 10 is an explanatory diagram of the range of the cross-sectional shape of the surface electrode in FIG. 7;

FIGS. 11A to 11D are schematic diagrams showing a manufacturing process of an outermost layer portion of a multilayer printed circuit board.

FIG. 12 is a side sectional view of an application example of the mounting structure of the present invention.

FIG. 13 is a cross-sectional view of a mounting structure in which a BGA is mounted on a conventional multilayer printed circuit board.

FIG. 14 is an enlarged view in which one periphery of a conventional spherical solder ball electrode is enlarged.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Multilayer printed circuit board, 2 ... BGA, 3 ... wiring, 4 ... Insulating layer, 5 ... Through-hole via, 7 ... Solder ball electrode, 8
… Surface electrode

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/46 H05K 3/46 Z F-term (Reference) 5E319 AA03 AB05 AC02 AC11 BB04 CC33 CD57 5E336 AA04 BB15 BC25 BC34 CC34 CC42 EE03 GG01 5E338 AA16 BB04 BB19 BB25 CC01 CD01 CD05 EE01 5E346 AA15 AA43 BB01 BB16 FF45 HH07 HH21 5F044 KK02 KK13 KK17 KK19 LL01

Claims (5)

[Claims] 1. An electric circuit device comprising: a wiring board having electrodes; and a semiconductor element arranged to be electrically connected via bumps, wherein an intersection line formed between a surface of the bumps and a surface of the electrodes. The surface of the electrode is oblique to a virtual plane including: 2. An electric circuit device having a wiring substrate having electrodes and a semiconductor element arranged to be electrically connected via bumps, wherein the electric circuit device is formed by at least a surface of the electrodes and a surface of the bumps. An electric circuit device, wherein the surface of the electrode is oblique to an imaginary plane including a boundary line formed by the joining ends. 3. The electrode according to claim 1, wherein the electrode has a concave surface with respect to a main surface of the wiring board, and the bump is arranged to cover the concave shape.
Or the electric circuit device according to 2. 4. A bump is arranged on an electrode provided on a surface of the wiring substrate, and the bump is heated and the bump is bonded to the electrode, so that the surface of the bump and the surface of the electrode are separated from each other. A method for manufacturing an electric circuit device, comprising a step of configuring a surface of the electrode so as to be oblique to a virtual plane including a line of intersection. 5. An electric component having a bump is disposed on an electrode provided on a surface of the wiring board, and the bump is connected to the electrode by pressing and holding the electric component against the wiring board. And manufacturing the electric circuit device, wherein the surface of the electrode is obliquely formed with respect to a virtual plane including a line of intersection between the surface of the bump and the surface of the electrode. Method.