JP2008141036A - Printed substrate and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of a connection part to an electronic component of a printed substrate against shock from an outside. <P>SOLUTION: A printed substrate 1 has a via hole 5 which is provided with a conductive material 10 in an inside passing through an insulating film and is formed in line at intervals back and forth and around, and a connection pad 4 for mounting a package 2 which is formed on the via hole 5 to be connected to the conductive material 10. The via hole 5 is formed in a position shifted in substantially a center direction in plane view of the package 2 joined to the connection pad 4 to substantially a center position of a plane view of the connection pad 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printed circuit board on which upper and lower circuits are electrically connected through a via hole formed in an insulating film, and a method for manufacturing the same.

  In recent years, due to the high integration, high speed, and thinning of semiconductor devices, the number of terminals has been increased and the pitch has been reduced, and the wiring boards for mounting semiconductor devices have higher than ever. There is a demand for a semiconductor device that can be mounted with high density and high accuracy and that has excellent reliability. As an example of a wiring board for mounting a semiconductor that is often used at present, a build-up board in which a chip size package (CSP), which is an electronic component, is mounted on a printed circuit board having a multilayer structure (for example, Patent Document 1). : JP-A-2001-284783) is well known.

JP 2001-284783 A

  Solder balls (ball grid array (BGA)) arranged in a grid on the chip size package are used to mount the chip size package on the build-up substrate as described above. However, when joining using solder balls, if the chip size package becomes smaller, the connection portion between the solder balls and the printed board tends to become smaller, so an apparatus equipped with a printed board to which the chip size package is joined (for example, When a device receives an impact from the outside during use of a mobile phone), mechanical stress may cause the package to fall off the printed circuit board or cause cracks in the printed circuit board. In such a case, a crack may develop due to further mechanical stress, and the connection portion may break.

  Conventionally, as a method of reinforcing against impact from the outside of the connection portion between the chip size package and the printed circuit board, a new member for strengthening such as reinforcing the target connection portion with a resin material or providing a case surrounding an electronic component There is a way to add. However, when the method of reinforcing with a resin material is used, depending on the material of the chip size package, the characteristics may change or become difficult to replace due to the reinforcement. In addition, when the method of providing a case surrounding the electronic component is used, it is necessary to secure an area for providing such a case on the substrate, which becomes an obstacle to high integration of semiconductor devices, or adds a case. The manufacturing cost was high. Furthermore, there is a method of increasing the rigidity of the printed board by increasing the thickness of the printed board or strengthening parts other than the printed board. However, if such a method is used, the chip size package and the printed board are bulky. It was difficult to reduce the size of the devices.

  By the way, the printed board has a through hole called a via hole that penetrates in the thickness direction of the board, and a conductive material mainly composed of copper, silver, nickel, solder, or the like is formed in the via hole. By filling, the connection pad connected to the circuit pattern on the upper surface side of the printed circuit board and the conductive material inside the via hole connected in contact with the connection pad are electrically connected. In such a contact connection, the adhesion between the connection pad and the conductive material inside the via hole is weak, and the connection pad is mainly held by adhesion to the resin part of the substrate. When received, the connection pad tends to be peeled off from the via hole at the contact portion between the connection pad having a weak adhesion and the conductive material inside the via hole.

  On the other hand, the connection pad and the conductive material filled in the via hole are heated to a predetermined temperature via a welding metal such as gold or copper and then crimped to connect the atoms of the welding metal to the connection pad. There is also an alloy connection method in which an alloy is formed between the connection pad and the conductive material inside the via hole by diffusing into the conductive material inside the via hole. In the case of such a method, an alloy is formed, and unlike the case of the contact connection described above, peeling of the connection pad from the conductive material inside the via hole due to insufficient adhesion does not occur. In some cases, the crack generated in the printed circuit board due to the stress is propagated toward the via hole and breaks the conductive material inside the via hole.

  In view of the problems as described above, it is an object of the present invention to provide a printed circuit board with improved durability of a connection portion with an electronic component against an external impact and a method for manufacturing the same.

  In order to solve the above problems, a printed circuit board according to the present invention includes a via hole penetrating an insulating film and provided with a conductive material therein, and an electronic component formed on the via hole (for example, the package 2 in the embodiment). ) And one or more via holes shifted in the direction of the center of the electronic component to be joined to the connection pad with respect to the position of the center of the connection pad. Formed in position.

  In the printed circuit board having the above structure, it is preferable that the conductive material inside the via hole and the connection pad are connected in contact.

  On the other hand, in the printed circuit board configured as described above, the conductive material inside the via hole and the connection pad may be alloy-connected.

  In the printed circuit board having the above-described configuration, the direction in which the via hole shifts may be a front-rear left-right direction in a plan view of the electronic component joined to the connection pad or a 45-degree direction with respect to these directions.

  Further, in the printed circuit board configured as described above, a plurality of via holes are arranged side by side, a plurality of connection pads are formed on each via hole, and an electronic component joined to the plurality of connection pads among the plurality of via holes Only the via hole corresponding to the peripheral edge in the plan view may be shifted in the substantially central direction in the plan view of the electronic component.

  On the other hand, in order to solve the above problem, a printed circuit board manufacturing method according to the present invention includes a via hole penetrating an insulating film and provided with a conductive material therein, and an electronic component formed on the via hole (for example, A printed circuit board manufacturing method comprising a connection pad for bonding a package 2) according to an embodiment, wherein one or more via holes are used as connection pads with respect to a substantially center position in plan view of the connection pad. It is formed at a position shifted in the approximate center direction of the electronic components to be joined.

  In the method for manufacturing a printed circuit board having the above-described configuration, it is preferable that the direction in which the via hole shifts is 45 degrees with respect to the front / rear and left / right directions in plan view of the electronic component joined to the connection pad.

  Furthermore, in the method for manufacturing a printed circuit board having the above-described configuration, a plurality of via holes are arranged side by side to form a plurality of connection pads on each via hole, and are joined to a plurality of connection pads among the plurality of via holes. Only the via hole corresponding to the peripheral edge of the electronic component in plan view may be shifted in the substantially central direction of the electronic component in plan view.

  According to the printed circuit board of the present invention, the via hole in which the conductive material is provided through the insulating film is bonded to the connection pad with respect to the center position of the connection pad. It is formed at a position shifted to. For this reason, even when mechanical stress such as impact is applied from the outside to the printed circuit board on which the electronic component is mounted, the connection pad that connects the printed circuit board and the electronic component or the inside of the via hole The durability of the conductive material is improved. Therefore, even when the connection portion is weakened due to high integration or thinning of the semiconductor device, it is possible to prevent the electronic component from falling off the printed circuit board or the connection portion from being broken.

  Further, by limiting the shift direction of the via hole to the front-rear and left-right directions in a plan view of the electronic component or to a direction of 45 degrees with respect to these directions, the design of the printed circuit board having the via hole can be made more than the case where it is not limited thereto. It becomes simpler and the manufacturing cost can be reduced.

  Instead of shifting all of the via holes formed on the printed circuit board, only the via holes corresponding to the peripheral edge of the electronic component having a large stress generated by mechanical shock are shifted. Even so, it can sufficiently resist external impacts.

  In addition, the printed circuit board manufacturing method according to the present invention adds a new member for strengthening such as reinforcing a resin material or providing a case surrounding an electronic component to a conventional structure such as a via hole or a connection pad. A case surrounding the electronic component is not provided, and the manufacturing process of the printed circuit board is the same as the conventional one, and an additional process and equipment are unnecessary, so that it can be manufactured at low cost. As described above, the method for manufacturing a printed board according to the present invention can be applied to a small apparatus such as a mobile phone in which the mounting space of the board is limited because it can cope with high integration and thinning of semiconductor devices.

  Hereinafter, a preferred embodiment of a printed circuit board according to the present invention will be described with reference to FIGS. 1 to 4.

  FIG. 1 is a sectional view showing a printed circuit board according to the present invention, and FIG. 2 is a plan view thereof. In the following description, the directions of arrows indicated as “front”, “rear”, “left”, “right”, “upper”, and “lower” in the figure are respectively forward, Rear, left, right, upper, and lower. As shown in FIG. 1, a chip size package 2 (CSP, hereinafter referred to as “package 2”), which is an electronic component, is mounted on the upper surface side of a printed circuit board 1 by solder bonding via solder balls 3. Although only one printed circuit board 1 is shown in FIG. 1, a build-up board having a multilayer structure in which a plurality of printed circuit boards 1 are stacked and electrically connected under the printed circuit board 1 is configured. Is done.

  In the printed circuit board 1, a plurality of via holes 5 having a substantially circular shape in plan view and penetrating in the thickness direction of the insulating film constituting the printed circuit board 1 are formed at substantially the same interval in the front, rear, left and right directions. In this embodiment, the via hole 5 has a diameter of about 100 μm, and is formed in five rows on the front and rear and five rows on the left and right. On the lower surface side of the printed circuit board 1, via forming recesses 6 having a substantially circular shape in a plan view and having a diameter of about 250 μm are formed toward the via holes 5. The via forming recess 6 communicates with the via hole 5, and a conductive material 10 mainly composed of paste-like copper, silver, nickel, solder, or the like is placed in the via forming recess 6. The conductive material 10 is filled. The conductive material 10 filled in the via forming recess 6 forms a land portion 11 connected to the circuit pattern formed on the lower surface of the printed circuit board 1.

  On the upper surface side of the printed circuit board 1, a plurality of connection pads 4 having a diameter of about 400 μm are formed so as to rise from the upper surface of the printed circuit board 1 in accordance with the terminal pitch of the package 2 to be mounted. For example, as shown in FIG. 2, the connection pads 4 are provided at intervals of about 0.8 mm in the front-rear and left-right directions. A part of the lower surface of the connection pad 4 is bonded to the conductive material 10 filled in the via hole 5, and the remaining part of the lower surface of the connection pad 4 is bonded to the insulating film of the printed circuit board 1. The bonding pad 4 is electrically connected to the circuit pattern formed on the upper surface of the printed circuit board 1, and the circuit pattern on the upper surface side and the circuit pattern on the lower surface side are in the bonding pad 4 and the via hole 5. It is electrically connected through the filled conductive material 10.

  Further, by bonding the solder ball 3 formed on the lower surface side of the package 2 to the upper surface of the connection pad 4, the package 2 and the printed board 1 are electrically connected via the solder ball 3. In this way, the package 2 (indicated by a chain line in FIG. 2) having a square shape in plan view is surface-mounted (surface mounted) on the upper surface side of the printed circuit board 1.

  Under such a configuration of the printed circuit board 1, when mechanical stress such as impact from the outside is applied to the printed circuit board 1 on which the package 2 is mounted, a connection pad interposed between the printed circuit board 1 and the package 2 In order to prevent the package 2 from falling off the printed circuit board 1 due to the peeling of the printed circuit board 4 from the printed circuit board 1, the present invention is characterized in that the via hole 5 and the via forming recess 6 are formed in the printed circuit board 1. Have.

  As shown in FIG. 2, the via hole 5 and the via forming recess 6 have a substantially center position (in FIG. 2) that is the center of gravity of the package 2 with respect to the connection pad 4 rather than the center position in plan view of the connection pad 4. It is formed at a position shifted in the direction indicated by point P). For example, the via hole 5 formed corresponding to the connection pad 4a (corresponding to the corner of the package 2) in FIG. 2 is in the direction from the center Q of the connection pad 4a to the point P, that is, to the right. It is located at a position shifted by about 75 μm in an obliquely 45 degree forward direction. By forming the via hole 5 and the via forming recess 6 in this manner, mechanical stress applied to the via hole 5 when an impact is applied to the package 2 can be reduced for the following reason.

  The stress relaxation effect of the via hole 5 will be described. When the package 2 receives a mechanical impact from the outside, the stress generated in the connection portion between the package 2 and the printed circuit board 1 such as the connection pad 4 and the conductive material 10 in the via hole 5 is seen in plan view. The peripheral edge portion (particularly, the four corners) of the package 2 is larger than the substantially central portion (around the point P) of the rectangular package 2. Therefore, by shifting the position of the via hole 5 toward the substantially central direction of the package 2 where the stress generated with respect to the connection pad 4 is relatively small, a crack is generated in the conductive material 10 due to the action of the stress accompanying the impact. Can be suppressed. Therefore, the conductive material 10 is prevented from being peeled off from the via hole 5 or broken inside the via hole 5.

  Here, the amount of shift of the via hole 5 is as small as possible that the via-forming recess 6 does not appear in the direction of the point P from the chain line L (see FIG. 2) that is in contact with the connection pad 4a and orthogonal to the line connecting the points P and Q. It is preferable to set as follows. This is because if the shift amount of the via hole 5 is large, the via hole 5 is detached from the connection pad 4, so that the connection pad 4 is easily peeled off, or the conductive material 10 in the connection pad 4 and the via hole 5. This is because the continuity of the circuit becomes worse. Further, if the connection pad 4 is shifted in the substantially center direction of the package 2 together with the shift of the via hole 5, the distance between the connection pad 4 adjacent to the shifted connection pad 4 is narrowed, and these connection This is because there is a possibility that a circuit pattern cannot be formed between the pads 4 and 4 or the solder balls 3 come into contact with each other when the package 2 is mounted.

  Further, by shifting the position at which the via hole 5 is formed in the direction of the approximate center of the package 2 as in the present invention, the via hole 5 can be obtained when the printed circuit board 1 on which the package 2 is mounted receives a mechanical shock. It is possible to prevent the connection pads 4 adhesively bonded to the inner conductive material 10 from being peeled off from the printed circuit board 1. This is because the stress generated in the connection pad 4 due to an external impact is concentrated on the edge side of the package 2, but the via hole 5 is formed at a shifted position as in the present invention. And the connection pad 4 and the printed circuit board 1 (printed circuit board 1) on the peripheral side of the package 2 are moved to a substantially central portion side of the package 2, which is a region where the stress (bonding surface) between the connection pad 4 and the connection pad 4 is relatively small. This is because the adhesion area with the interface with the insulating resin constituting the substrate 1 is increased. In this way, in the present invention, since the bonding portion between the connection pad 4 and the conductive material 10 in the via hole 5 is set in a region where stress is relatively small, durability against external impact is improved. The connection pad 4 can be made difficult to peel off from the printed circuit board 1.

  In another embodiment of the present invention, the via hole 5 is not adhesively connected to the connection pad 4 but the conductive material 10 filled in the via hole 5 and the connection pad 4 are connected via a metal such as copper or gold. Thus, an alloy may be formed. In this embodiment, since the distance between the crack generation source and the via hole 5 is increased by shifting the via hole 5 in the substantially central direction of the package 2, the via hole 5 is generated at the edge of the connection pad 4 on the edge side of the package 2. Thus, cracks propagating toward the via hole 5 are difficult to reach the via hole 5, and the via hole 5 can be prevented from breaking.

  Note that the position configuration in which the via hole 5 and the via forming recess 6 are formed is not limited to the one shown in FIG. 2, but may be the position configuration shown in FIG. 3 instead. In the present embodiment, as shown in FIG. 3, the shift direction of the via hole 5 and the via forming recess 6 is limited to the front-rear and left-right directions in FIG. The difference between this embodiment and the embodiment shown in FIG. 2 is that in the embodiment shown in FIG. 2, there is a via hole 5 shifted in the direction of 60 degrees from the center toward the point P, but there are 8 connections. The via holes 5 and via forming recesses 6 corresponding to the pads 4b (see FIG. 3) are shifted in the front / rear / right / left direction or 45 degrees from the center. By limiting the shift direction in this way, the design of the printed circuit board 1 having the via hole 5 becomes easier and the manufacturing cost can be reduced than when the shift direction is not limited thereto.

  Alternatively, in the printed circuit board 1 according to the present invention, as shown in FIG. 4, the via holes 5 and via forming recesses 6 to be shifted are not all via holes 5 and via forming recesses 6 formed in the printed circuit board 1. Only the via hole 5 and the via forming recess 6 corresponding to the peripheral edge of the package 2 in plan view may be shifted in the substantially central direction of the package 2. As described above, even when only the via hole 5 corresponding to the edge side of the package 2 where the stress generated by mechanical impact is large is shifted and formed, it is possible to counter the impact from the outside. it can. In this case, the shift direction of the via hole 5 may be 45 degrees from the center or may not be limited to the 45 degrees.

  As described in detail above, according to the printed circuit board of the present invention, the via hole having the conductive material provided inside through the insulating film is a connection pad with respect to the center position of the connection pad. It is formed at a position shifted in a substantially central direction of the electronic components to be joined. For this reason, even when mechanical stress such as impact is applied from the outside to the printed circuit board on which the electronic component is mounted, the connection pad that connects the printed circuit board and the electronic component or the inside of the via hole The durability of the conductive material is improved. Therefore, even when the connection portion is weakened due to high integration or thinning of the semiconductor device, it is possible to prevent the electronic component from falling off the printed circuit board or the connection portion from being broken.

  Further, by limiting the shift direction of the via hole to the front-rear and left-right directions in a plan view of the electronic component or to a direction of 45 degrees with respect to these directions, the design of the printed circuit board having the via hole can be made more than the case where it is not limited thereto. It becomes simpler and the manufacturing cost can be reduced.

  Instead of shifting all of the via holes formed on the printed circuit board, only the via holes corresponding to the peripheral edge of the electronic component having a large stress generated by mechanical shock are shifted. Even so, it can sufficiently resist external impacts.

  In addition, the printed circuit board manufacturing method according to the present invention adds a new member for strengthening such as reinforcing a resin material or providing a case surrounding an electronic component to a conventional structure such as a via hole or a connection pad. A case surrounding the electronic component is not provided, and the manufacturing process of the printed circuit board is the same as the conventional one, and an additional process and equipment are unnecessary, so that it can be manufactured at low cost. As described above, the method for manufacturing a printed board according to the present invention can be applied to a small apparatus such as a mobile phone in which the mounting space of the board is limited because it can cope with high integration and thinning of semiconductor devices.

  The printed circuit board and the manufacturing method thereof according to the present invention can be applied to manufacturing industries such as mobile phones and digital home appliances.

It is AA sectional drawing in FIG. 2 which shows the printed circuit board concerning this invention. It is a top view which shows the said printed circuit board. It is a top view which shows embodiment different from FIG. 2 of the said printed circuit board. It is a top view which shows embodiment different from FIG. 2 and FIG. 3 of the said printed circuit board.

Explanation of symbols

1 Printed circuit board 2 Package (electronic component)
3 Solder ball 4 Connection pad 5 Via hole 6 Via forming recess 10 Conductive material 11 Land part P Center position of package Q Center position of connection pad 4a

Claims (8)

In a printed circuit board comprising a via hole penetrating an insulating film and provided with a conductive material therein, and a connection pad formed on the via hole for joining an electronic component,
The one or more via holes are formed at positions shifted in a substantially center direction in a plan view of the electronic component joined to the connection pad with respect to a substantially center position in the plan view of the connection pad. Printed circuit board.   The printed circuit board according to claim 1, wherein the conductive material inside the via hole and the connection pad are contact-connected.   The printed circuit board according to claim 1, wherein the conductive material inside the via hole and the connection pad are alloy-connected.   The direction in which the via hole shifts is a front-rear left-right direction in a plan view of the electronic component joined to the connection pad, or a 45-degree direction with respect to these directions. Printed circuit board as described in 1. A plurality of the via holes are arranged side by side, and a plurality of the connection pads are formed on each of the via holes,
Of the plurality of via holes, only the via hole corresponding to the peripheral edge portion in plan view of the electronic component joined to the plurality of connection pads is shifted in a substantially central direction in plan view of the electronic component. The printed circuit board according to any one of claims 1 to 3. A printed circuit board manufacturing method comprising a via hole penetrating an insulating film and provided with a conductive material inside, and a connection pad formed on the via hole for joining an electronic component,
One or more of the via holes are formed at positions shifted in a substantially central direction of the electronic component joined to the connection pad with respect to a substantially center position in plan view of the connection pad. Manufacturing method.   7. The printed circuit board according to claim 6, wherein a direction in which the via hole is shifted is a front-rear left-right direction in a plan view of the electronic component joined to the connection pad or a 45-degree direction with respect to these directions. Manufacturing method. A plurality of the via holes are arranged side by side, and a plurality of the connection pads are formed on each of the via holes,
Of the plurality of via holes, only the via hole corresponding to the peripheral edge portion in plan view of the electronic component joined to the plurality of connection pads is shifted in a substantially central direction in plan view of the electronic component. A method for manufacturing a printed circuit board according to claim 6.

Images