JPH10335796A - Circuit board and electronic circuit device and manufacture thereof, and inspection of junction thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such a circuit board that junctions of an electronic circuit device made by joining an electronic circuit element and the circuit board can be easily inspected by a visual inspection or mechanical and physical inspection and a method for manufacture thereof, provide an electronic circuit device which has an improved junction reliability and a method for manufacture thereof, and provide an easy and non-destructive method for inspecting the junctions of the electronic circuit device. SOLUTION: In a circuit board 16 which has electrode sections in such places as to correspond to many electrode sections of an electronic circuit element and which constitutes an electronic circuit device, by being joined by the electrode sections of the electronic circuit element, the shape of soldering lands 150 is nearly polygon, in other words, either tetragon, pentagon, hexagon, heptagon, or octagon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board which forms an electronic circuit device by bonding an electronic circuit element to at least a part thereof, an electronic circuit device thereof, a method of manufacturing the same, and a method of inspecting a bonded portion thereof. It is.

[0002]

2. Description of the Related Art Conventionally, as a manufacturing technique of an electronic circuit device constituted by electrically joining an electronic circuit element to a circuit board, a method by wire bonding, a TAB (T
ape Automated Bonding), CCB (Controlle
d Collapsed Bonding), BGA (Ball Grid A
rray), a CSP (Chip Size Package) bonding method, and the like are known. Among them, CCB, BGA, and CSP have recently attracted attention in multi-pin bonding.
There is a method.

[0003] The method using CCB is disclosed, for example, in USP3,
292,240, USP 3,303,393. This CCB method is shown in FIGS.
An example will be described. FIG. 5A shows a cross section of an electronic circuit element to be joined. Barrier layer 103 on electrode 102
Electronic circuit element 1 provided with solder bumps 104 through
01 is prepared. Next, the electrode 10 of the electronic circuit element 101
Circuit board 110 having electrode 111 at a position opposed to 2
Prepare After that, the electrode 102 of the electronic circuit element 101
And the electrode 111 of the circuit board 110 are positioned.
At 12, soldering is performed. At this time, the melting point of the solder bump 104 is higher than the melting point of the solder 112, and the soldering temperature is between the melting point of the solder bump 104 and the melting point of the solder 112. Does not melt. FIG. 5B shows a cross-sectional view after bonding.

[0004] The BGA method is disclosed, for example, in US Pat.
239,198, USP 5,285,352, USP
5,381,307 and USP 5,397,921. FIG. 6 shows representative examples of these. First, as shown in FIG. 6A, the IC chip 1 is mounted on the circuit board 120.
21 is die-bonded, wire-bonded, and sealed, and a solder ball 122 is bonded to the electrode 121 on the surface opposite to the mounting surface of the IC chip 121 on the circuit board 120 to assemble the electronic circuit element BGA123. Next, a circuit board 124 having an electrode 125 at a position corresponding to the electrode 121 of the electronic circuit element BGA 123 is prepared. FIG. 7 is an enlarged view of the circuit board 124 viewed from the electrode 125 side.
In this example, there are 10 × 10 electrodes 125 and the outer circumference 2
The rows have a pattern on the front surface, but the other electrodes are electrically connected to the inner layer or the back surface through through holes (not shown). The parts other than the electrode part 125 are insulated by the solder resist.

Next, a desired cream solder is applied on the electrodes 125 of the circuit board 124,
5 and the electrode 121 of the electronic circuit element 123 are positioned,
Perform soldering. The cross section after soldering is shown in FIG. The method using the CSP is described, for example, in US Pat.
861. In this method, a land having substantially the same size as an electrode land on a semiconductor chip is connected to an opposing land on a circuit board. Monthly Semi
conductor Word 1995.5. The CSPs of each company are introduced in the special feature of PP103-131 "Which is the mainstream CSP or bare chip?"

[0006]

However, there are the following problems in the electronic circuit device constructed by joining the above-mentioned conventional electronic circuit element to a circuit board. <Problems of the Method Using CCB> In FIG. 5B, visual inspection is performed to check the quality of soldering at the joint 113 of the electronic circuit device in which the electronic circuit element 101 and the circuit board 110 are soldered. Alternatively, there are a mechanical physical method and an electric method. However, the former method uses the joint 11
3 is blocked by the electronic circuit element and the circuit board, and it is difficult to inspect. In particular, if the bonding portion 113 is fine, the gap amount Δg between the electronic circuit element and the circuit board is small, or if the bonding portion 113 exists inside the electronic circuit element (not shown). It is hard to inspect. for that reason,
A method of observing an image by transmitting soft X-rays is known. However, in soft X-ray transmission observation, the joint 11
No. 3 solder is insufficient or the adjacent joint 113
Is relatively easy to observe when the bridge is formed by soldering, but when the metals of the joint 113 are not wet with solder or when proper diffusion bonding is not performed, so-called solder , Difficult to observe.

<Problems of the BGA method> The BGA method has the same problems as described above. FIG. 8 is an enlarged view of the joint 126 shown in FIG. FIG. 9 is a cross-sectional view of the joint 126 when cut along the slice planes A1 to A5 in FIG.
2 shows a cross-sectional shape of the hologram. A1 is an electronic circuit element BGA
The shape of the opening of the electrode 121 from the resist 127 is shown. A5 indicates an opening shape of the electrode 125 from the resist 128 of the circuit board 124. Generally, A1
And A5 show a circular shape. A2 is slightly larger than A1 and has the largest size at A3. Similarly, A4 is slightly larger than A5. However, if the solder of the solder ball 122 and the electrode 125 of the circuit board 124 are not wetted by the solder or the appropriate diffusion bonding is not performed, the shape from A5 to A4 does not increase almost continuously, but becomes improper. Continuous, irregular, A4
May be too small. This phenomenon is difficult to observe visually from the outside. In FIG. 8, when the paper is irradiated with X-rays from above to below and detected by the lower sensor, the density is almost the same in the smaller one of A1 and A5, but the amount of X-rays gradually increases outside the smaller one. To go. When this is expressed in shades, it gradually fades from inside to outside. However, it is difficult to monitor the above phenomenon between A5 and A4 even with X-rays.

Although the case of CCB and BGA has been described above, the case of face-down joining such as CSP may also be used.
The above-described problem occurs. SUMMARY OF THE INVENTION It is an object of the present invention to provide a circuit board in which a junction of an electronic circuit device in which an electronic circuit element and a circuit board are joined can be easily inspected visually or by a mechanical and physical method. Another object of the present invention is to provide an electronic circuit in which a joint of an electronic circuit device in which an electronic circuit element and a circuit board are joined is easily inspected visually or by a mechanical and physical method, and the joining reliability is further improved. It is to provide a device.

Still another object of the present invention is to make it easier to visually inspect or visually inspect a joint of an electronic circuit device in which an electronic circuit element and a circuit board are joined, and to improve the reliability of the joint. It is an object of the present invention to provide an improved method for manufacturing an electronic circuit device. Still another object of the present invention is to provide an inspection method for easily and non-destructively inspecting a joint of an electronic circuit device in which an electronic circuit element and a circuit board are joined.

[0010]

In order to solve this problem, a circuit board according to the present invention is a circuit board having an electrode portion at a position corresponding to a large number of electrode portions of an electronic circuit element. In a circuit board which is connected to an electrode portion of an element to constitute an electronic circuit device, at least one of a large number of electrodes is substantially polygonal in shape. Here, the substantially polygonal shape is any one of a quadrangle, a pentagon, a hexagon, a heptagon, and an octagon.

Further, in the electronic circuit device of the present invention, an electronic circuit element having a large number of electrode parts is opposed to a circuit board having an electrode part at a position corresponding to the electrode part of the electronic circuit element.
In an electronic circuit device configured by connecting an electrode portion of the electronic circuit element and an electrode portion of the circuit board, at least one of the connected portions of the plurality of connected electrodes is closer to the circuit board. Is characterized in that its cross-sectional shape is substantially polygonal. Here, the substantially polygonal shape is any one of a quadrangle, a pentagon, a hexagon, a heptagon, and an octagon.

Further, a method of manufacturing an electronic circuit device according to the present invention
An electronic circuit element having a large number of electrode parts and a circuit board having an electrode part at a position corresponding to the electrode part of the electronic circuit element are opposed to each other, and the electrode part of the electronic circuit element and the electrode part of the circuit board are formed. In a method of manufacturing an electronic circuit device to be connected,
The circuit board includes at least one electrode having a substantially polygonal shape. Here, the substantially polygonal shape is any one of a quadrangle, a pentagon, a hexagon, a heptagon, and an octagon.

Further, according to the present invention, there is provided a method for inspecting a joint portion, wherein an electronic circuit element having a large number of electrode parts is opposed to a circuit board having an electrode part at a position corresponding to the electrode part of the electronic circuit element. A method for inspecting a joint of an electronic circuit device configured by connecting an electrode of an electronic circuit element and an electrode of the circuit board, wherein the electrode has a substantially polygonal shape. And connecting the electrode part of the electronic circuit element and the electrode part of the circuit board, and judging the quality of the bonding of the bonding part based on an axial transmission image of the bonding part. And Here, if the transmission image is a substantially polygonal shape similar to the substantially polygonal shape of the electrodes on the circuit board, the bonding is good, and the transmissionable image is not a substantially polygonal shape similar to the substantially polygonal shape of the electrodes on the circuit board. Defect. Further, the substantially polygonal shape is any one of a quadrangle, a pentagon, a hexagon, a heptagon, and an octagon.

[0014]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. (First Embodiment) FIGS. 1 and 2 show a circuit board, an electronic circuit device, and a method of manufacturing the same according to a first embodiment.
FIG. 1 shows a circuit board 16 for BGA bonding according to the first embodiment.
0 shows the shape and arrangement of the soldering lands 150.
FIG. 2 is a cross-sectional view in which the BGA 164 is soldered to the circuit board 160.

The circuit board 160 has a large number of electrodes 164, and the shape of the electrodes 164 is a substantially hexagonal solder land 150 made of a resist. Soldering land 150
The maximum value of the distance connecting the two vertices corresponds to the diameter of the conventional circular land, the pitch corresponds to the pitch of the electrodes of the electronic circuit element, and the electrodes and the wiring pattern are made of copper foil. The wiring pattern is omitted because it is not particularly necessary. The circuit board material is FR-4, 4-layer board.

First, the soldering lands 1 on the circuit board 160
After the solder paste is printed on the BGA 50, the BGA 16 having the solder lands 150 and the solder holes of the circuit board 160 is formed.
4 is positioned, and soldering is performed by reflow. FIG. 2 shows a bonding diagram after reflow. (Second Embodiment) FIG. 4 shows a circuit board according to a second embodiment. The manufactured electronic circuit device and its manufacturing method are the same as in the first embodiment.

FIG. 4 shows the shape and arrangement of the soldering lands 150 of the circuit board 160 for BGA bonding according to the second embodiment. The circuit board according to the second embodiment is different from the circuit board according to the first embodiment in that the shape of the electrode 164 is a substantially pentagonal soldering land 150 made of resist, and the number of pins of the electronic circuit element BGA is different. In response to this, the number of pins on the circuit board is reduced and the arrangement is in three rows around the periphery.

In this embodiment, an electronic circuit device is manufactured in the same manner as in the first embodiment. Hereinafter, the materials constituting the above embodiment will be described in detail. As the circuit board of the present embodiment, for example, a resin circuit board, a ceramic circuit board, a metal core circuit board, a silicon circuit board,
And a flexible circuit board. It has a large number of electrodes and wiring patterns on its surface. In the case of a double-sided substrate, it has a pattern layer connected by through holes and via holes. In the case of a multilayer substrate, it further has a wiring pattern inside. In this embodiment, the effect becomes more remarkable as the number of electrodes of the electronic circuit element is larger and the arrangement of the electrodes is located inside the electronic circuit element.

As the electronic circuit element of the present embodiment, I
Semiconductor devices such as C and LSI, and BGA, CSP, MCM and the like in which they are packaged. Each of these electronic circuit elements has an electrode for making an electrical connection to the outside, and has two or more electrodes. In this embodiment, an electrode of a circuit board and an electrode of an electronic circuit element are connected by soldering. The solder may be provided in advance on one or both of the electrodes of the circuit board and the electrodes of the electronic circuit element. The solder is preferably in a ball shape, but does not have to be a ball-shaped bump. Alternatively, the electronic circuit element may be mounted after printing a solder paste or a flux on the electrode portion of the circuit board or applying the solder paste or the flux by a method such as a dispenser. The soldering may be performed by a known method, and in the case of eutectic tin-lead solder, the solder is melted and joined in the range of 190 to 280 ° C.

(Example of Inspection of Joint) Usually, the joint of an electronic circuit device joined by soldering is inspected. As described above, a method of observing an image by soft X-ray transmission is known for inspecting a joint part formed by face-down joining. Soft X-rays have different X-ray transmission conditions depending on the thickness of the solder. That is, when the solder is thicker, the amount of X-ray transmission decreases, and when the solder is thinner, the X-ray transmission amount increases.

In FIG. 8, the soldering lands of the electrodes 125 on the circuit board 124 (the shape of the area where soldering is possible, the electrodes are enlarged and opened with a resist, or the electrode shape becomes the soldering lands as they are) There is an n-gon (n is 3
As described above, preferably, in the case of 4 to 8), in the case of proper soldering, the shape closer to the soldering land of the electrode 125 is closer to the A4 surface as the surface is closer to the electrode 125. On the other hand, if the solder ball 122 is not wet or proper diffusion bonding is not performed, the surface tension of the solder of the solder ball 122 becomes larger than the force of the solder to wet the electrode, and the surface tension acts to reduce the surface area. To form a substantially circular shape or an irregularly discontinuous shape.

Therefore, a similar image can be obtained with X-rays.
However, in the case of FIG. 8, since A3 is large, it is more conspicuous if one or both of the X-ray source and the electronic circuit device are moved at an arbitrary angle to take a plurality of X-ray images and perform image processing. Image is obtained. If the soldering lands of the electrodes 125 of the circuit board 124 are triangular, the bonding portion becomes acute and the reliability of the bonding is deteriorated. Or a polygon.

Although the soldering lands are substantially regular hexagons and substantially regular pentagons, it is also possible to inspect the bonding quality with X-rays in the case of regular octagons as well. In addition, the shape is not limited to a regular polygon, and the object of the present invention can be achieved as long as the polygon can be distinguished from a circle and has a range that does not adversely affect the joining state. Further, in the description of the present embodiment, an example is shown in which the BGA 164 and the circuit board 160 (150) correspond one-to-one, but the same applies to a case where a plurality of BGAs are mounted on a circuit board. It is clear that it works.

[0024]

【Example】

(Example Corresponding to First Embodiment) A first embodiment will be described with reference to FIGS. Here, FIG.
It shows a line transmission image (image processed). The circuit board 160 has 100 electrodes 164 of 10.times.10, and the shape of the electrodes 164 is a substantially hexagonal soldering land 150 made of a resist. The size of the soldering land 150 is the maximum value of the distance connecting the two vertices and φ
The pitch of the soldering lands 150 was 1.27 mm, and the electrodes and wiring patterns were copper foil.
The soldering lands 150 of the circuit board 160 are arranged at positions corresponding to the electrodes 165 of the BGA 164 having 100 pins. The circuit board material is FR-4, 4-layer board.

First, the solder lands 1 on the circuit board 160
After the solder paste is printed on the BGA 50, the BGA 16 having the solder lands 150 and the solder holes of the circuit board 160 is formed.
4 was positioned, and soldering was performed by reflow. FIG. 2 shows a bonding diagram after reflow. The bonding state after the bonding was good, the soldering strength was satisfactory, and a reliable electronic circuit device was obtained.

Thereafter, the bonding state was inspected using X-rays. The inspection apparatus used was a Shimadzu microfocus X-ray television inspection apparatus: SMX-30 & CT system of Shimadzu Corporation. This apparatus can observe a cross-sectional image using a CT scan and three-dimensional image processing. FIG. 3 (a)
FIG. 3B shows an X-ray transmission diagram of one joint.
FIG. 4 is a diagram in which the image of FIG. 3A is further subjected to image processing to set a certain threshold level. (C) of FIG.
The X-ray transmission diagram shows the result of bonding performed under the same conditions except that the copper foil of the soldering land of the circuit board 160 was oxidized before reflow. When the bonding strength of the sample performed in FIG. 3 (c) was measured, the peel strength was less than half that of FIG. 3 (a). Also, the fractured surface was not the entire soldering land 150 but a small portion considered to have been joined. From this fact, it was found that if the soldering lands were substantially regular hexagons, the quality of the bonding could be inspected nondestructively. That is, when a substantially regular hexagonal shape of the soldering land of the circuit board 160 can be clearly observed in the X-ray transmission diagram (see FIGS. 3A and 3B), it is good and not clearly observed (indistinguishable from a circle): In the case of FIG. 3C), it can be determined that there is a defect.

(Example Corresponding to the Second Embodiment) As shown in FIG.
It is a rectangular soldering land 150 and is an electronic circuit element BG
In the case where the number of pins of the circuit board is 84 pins corresponding to the number of pins A and the arrangement is three rows around, the same bonding processing and the inspection of the bonding part as in the first embodiment are performed. Was.

In this embodiment, as in the first embodiment, a good electronic circuit device was obtained as in the first embodiment, and it was confirmed that the quality of the bonding could be inspected by X-rays. The soldering lands were made into a regular hexagon and a regular pentagon, but the same observation result was obtained with a regular octagon to a regular octagon, so that the bonding quality can be inspected by X-rays. Was confirmed.

[0029]

As described above, according to the present invention, it is possible to provide a circuit board in which the joint of an electronic circuit device in which an electronic circuit element and a circuit board are joined can be easily inspected visually or by a mechanical and physical method. Further, it is possible to provide an electronic circuit device in which the joint of the electronic circuit device in which the electronic circuit element and the circuit board are joined can be easily inspected visually or by a mechanical and physical method, and the joining reliability is further improved.

In addition, it is easy to inspect the joint of the electronic circuit device in which the electronic circuit element and the circuit board are joined by a visual or mechanical physical method, and to manufacture an electronic circuit device in which the joining reliability is further improved. We can provide a method. Further, it is possible to provide an inspection method for easily and nondestructively inspecting a joint of an electronic circuit device in which an electronic circuit element and a circuit board are joined.

That is, in an electronic circuit device in which electronic circuit elements are joined face-down to a circuit board, if the shape of the soldering land of the circuit board is polygonal, proper soldering is performed with the soldering lands of the circuit board. Since the X-ray transmission apparatus can recognize the presence of the circuit board, the circuit board and the electronic circuit device having high reliability can be provided because the inspection can be performed nondestructively.

This effect becomes more remarkable as the junction of the electronic circuit element is finer and as the junction of the electronic circuit element is located inside.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a circuit board according to a first embodiment.

FIG. 2 is a diagram illustrating an electronic circuit device after bonding according to the present embodiment.

FIG. 3 is a diagram schematically illustrating an X-ray transmission diagram of a bonded portion after bonding according to the first embodiment.

FIG. 4 is a diagram illustrating a circuit board according to a second embodiment.

FIG. 5 is a diagram for explaining a conventional CCB method.

FIG. 6 is a diagram for explaining a conventional BGA method.

FIG. 7 is a diagram for explaining a surface of a circuit board.

FIG. 8 is an enlarged view of a joint shown in FIG. 6 (b).

FIG. 9 is a diagram schematically showing a cross-sectional shape of the A1-A5 plane in FIG. 8;

Claims (9)

[Claims] 1. A circuit board having an electrode portion at a position corresponding to a number of electrode portions of an electronic circuit element, wherein the circuit board is connected to the electrode portion of the electronic circuit element to form an electronic circuit device. Wherein at least one of the electrodes has a substantially polygonal shape. 2. The circuit board according to claim 1, wherein the substantially polygon is any one of a quadrangle, a pentagon, a hexagon, a heptagon, and an octagon. 3. An electronic circuit device having a large number of electrode parts,
In an electronic circuit device configured by facing a circuit board having an electrode portion at a position corresponding to the electrode portion of the electronic circuit element and connecting the electrode portion of the electronic circuit element and the electrode portion of the circuit board, An electronic circuit device, wherein a cross-sectional shape of at least one of the connected portions of the plurality of connected electrodes on the circuit board side is substantially polygonal. 4. The electronic circuit device according to claim 3, wherein said substantially polygonal shape is any one of a quadrangle, a pentagon, a hexagon, a heptagon, and an octagon. 5. An electronic circuit device having a number of electrode portions,
In a method for manufacturing an electronic circuit device, a circuit board having an electrode portion is opposed to a position corresponding to an electrode portion of the electronic circuit element, and the electrode portion of the electronic circuit element is connected to the electrode portion of the circuit board. A method for manufacturing an electronic circuit device, wherein the circuit board includes at least one electrode having a substantially polygonal shape. 6. The method according to claim 5, wherein the substantially polygonal shape is any one of a quadrangle, a pentagon, a hexagon, a heptagon, and an octagon. 7. An electronic circuit element having a large number of electrode parts,
A circuit board having an electrode portion at a position corresponding to the electrode portion of the electronic circuit element is opposed to the circuit board, and the electrode portion of the electronic circuit element is connected to the electrode portion of the circuit board. A method for inspecting a joint for inspecting a part, comprising: using a circuit board whose electrode shape is substantially polygonal, connecting an electrode part of the electronic circuit element and an electrode part of the circuit board, A method for inspecting a joint of an electronic circuit device, comprising: judging the quality of the joint at the joint based on the transmission image in the axial direction. 8. If the transmission image is a substantially polygonal shape similar to the substantially polygonal shape of the electrodes of the circuit board, the bonding is good, and the transmission image is a substantially polygonal shape similar to the substantially polygonal shape of the electrodes of the circuit board. 9. The method according to claim 8, wherein a defect is provided if there is no defect. 9. The method according to claim 7, wherein the substantially polygonal shape is any one of a quadrangle, a pentagon, a hexagon, a heptagon, and an octagon.