JP4860641B2 - Electronic component circuit board - Google Patents

Description

  The present invention relates to an electronic component circuit board and, for example, relates to a structure of a circuit board mounted with an electronic component mounted on a control device.

  In recent years, the functions of individual control devices such as engine control, throttle control, and brake control have been improved in automobile control devices, and further function improvements have been required through cooperation between navigation systems and individual control devices. Yes.

  As these functions are improved, it is required to improve the mounting density of electronic components. With the mounting density of electronic components of a conventional control device, there is a problem that it cannot be installed in a restricted space in an automobile.

  Therefore, as one of the solutions to the above problem, a method has been proposed in which a BGA (ball grid array) electrode terminal is introduced into a module substrate on which electronic components are mounted to improve the mounting density and mounted on the circuit board of the main body. Yes.

  On the module board into which the BGA electrode terminals are introduced, a large number of solder bumps of about 0.5 to 1.5 mm are arranged in a matrix on the mounting surface of the circuit board and connected to the land of the circuit board.

  The circuit board and the mounted module board generate thermal stress due to the heat generation and cooling temperature cycles of the electronic components, and the difference (strain) with respect to the expansion of the circuit board and the module board with different coefficients of thermal expansion is common. In the quadrangular module substrate, the thermal stress is greatest at the four corners because the heat source and the main fulcrum of both are added from the center of the module substrate toward the concentric circle.

  For this reason, cracks are most likely to occur at the solder joints of the bumps that transmit corner signals, thereby causing a problem that signals cannot be transmitted.

  In order to solve this problem, in a square module board, a plurality of dummy bumps or bumps for specific signals are arranged so that a plurality of bumps are integrated at four corners when mounted on a circuit board, and thermal stress is Japanese Patent Application Laid-Open No. H10-228707 describes a technique for reinforcing solder strength and preventing solder cracks in bumps that transmit signals.

  In addition, regarding the mounting of semiconductor chips, a technology is known that arranges dummy bumps of the same shape as the signal bumps uniformly on the outermost periphery of the square shape to reinforce the strength due to thermal stress and prevent solder cracks in the bumps that transmit signals It is described in Document 2.

JP 2001-177226 A JP 2007-220954 A

  However, in Patent Document 1, since the bump shape on the module board side is unified, it is advantageous for productivity. However, the bumps arranged at the corners on the module board side are replaced with dummy bumps or specific signals at the corners on the circuit board side. Since it is integrated with the bumps for use, it becomes impossible to wire the bumps at the corners as signal lines, which is a hindrance to substantially improving the mounting density.

  In Patent Document 2, dummy bumps are arranged on the outermost periphery of the module substrate, and a sufficient effect can be obtained for strengthening the strength by thermal stress. On the other hand, the number of bumps increases, and the amount of material used increases and productivity decreases. Occurs. Further, this technique is intended for mounting an integrated circuit chip, and has a problem that the number of dummy bumps increases when applied to a module substrate having a large surface area on which various electronic components are mounted.

  Further, in Patent Document 1 and Patent Document 2, the bump shape and the number of arrays arranged from the four corners of the module substrate are the same, and a technique corresponding to the outer shape of the module substrate is not described.

  The present invention has been made in view of such a situation, and even in a module substrate having a large surface area having a long side and a short side that are not limited to a square, the strength due to thermal stress is reinforced to destroy a signal bump. It is an object to provide an electrode structure of an electronic component mounting substrate that can improve productivity while preventing the above.

  In order to solve the above problems, in the present invention, the signal bumps at the corners of the module board are protected to provide a highly reliable solder connection, and the minimum necessary dummy bumps are arranged at appropriate positions in the module board. Means for realizing an electrode structure of an electronic component mounting substrate is provided.

  That is, the mounting structure of the electronic component circuit board according to the present invention is a structure in which electrodes are formed by solder bump groups arranged in a grid array on the back surface of a rectangular module board in which a plurality of electronic components are wired, and mounted on the circuit board. 2 includes a signal bump group to which a signal line is connected and a dummy bump group to which no signal is connected to the outer periphery thereof, which are arranged in parallel to the sides of the rectangular module substrate. Among the dummy bump groups, those arranged in parallel to one opposite two sides of the module substrate include the center of the signal bump group, and those arranged in parallel to the other two opposite sides are one opposite two sides. The center of the dummy bump group and the center of the signal bump group arranged in parallel to each other are not included.

  In this case, the dummy bump including the center may be arranged on a line that coincides with the center of the signal bump, and the dummy bump not including the center may be arranged on an intermediate line between the signal bump and the signal bump.

  In addition, the signal bumps closest to the four corners of the square module substrate and the center of the two dummy bumps closest to the signal bumps are arranged so as to form an isosceles triangle close to an equilateral triangle. Also good.

  In addition, the dummy bumps arranged in parallel on each side on the module substrate are divided into groups of two locations on each side, starting from positions closest to the four corners of the quadrangular substrate, and 8 locations on all sides. The structure may be divided into groups.

  Further, the group of two places on each side may have a structure in which about one third of the section bumps are not arranged around the middle line of each side.

  In addition, the dummy bump group divided into eight places may be arranged with the number of bumps in one group different from the number of bumps in the other group, and the number of bumps in one group is the number of bumps in the other group. The structure may be at least one less than that at least, or at least one more. Alternatively, for a module substrate having two long sides and two short sides and having a structure in which four dummy bump groups arranged on the long side are larger than the number of bumps of the four dummy bump groups arranged on the short side Further, the dummy bump group having four long sides or the dummy bump group having four short sides may be arranged so that the number of bumps in one group is different from the number of bumps in the other group. Alternatively, the number of different numbers may be at least one less, or at least one more.

  The rectangular module substrate may have a structure in which a plurality of dummy bumps or signal bumps of specific signals are arranged at a position including the center.

  Further, the signal bumps and the dummy bumps may be formed at an equal pitch in the same molding process.

  Further, the rectangular module substrate on which a plurality of electronic components are wired may have a resin-sealed structure by transfer molding.

  According to the present invention, even in a module substrate having a large surface area with long sides and short sides that are not limited to a square, it is possible to improve productivity while reinforcing the strength due to thermal stress and preventing destruction of signal bumps. it can.

Embodiments of the present invention will be described below with reference to the drawings.
<First Embodiment>
First, in this embodiment, a means for realizing an electrode structure of an electronic component mounting substrate in which a minimum necessary number of dummy bumps are arranged at appropriate locations in a module substrate unique to the present application, mainly for the purpose of improving productivity will be described.

  FIG. 1 shows an electronic circuit module 1 in which a bump 100 connected to a connection pad 21 of a circuit board 20 is mounted on one surface of a module substrate 11 and an electronic component 12 is mounted on the other surface and then transferred and molded 13. It is a figure which shows a side surface.

  The electronic circuit module 1 is mounted with a component in which one function is integrated, and a plurality of electronic circuit modules 1 and electronic components are mounted and wired on the circuit board 20 to control a device to be controlled. Function as.

  For example, engine control, automatic transmission control, and the like are typical examples of automobile control devices.

FIG. 2 is a diagram illustrating an arrangement of the bumps 100 of the module substrate 11.
The module substrate 11 has a rectangular shape with long sides 11A and 11B and short sides 11C and 11D.

  As for the bumps of the module substrate 11, dummy bump groups 105 to 112 arranged on the outermost peripheral lines 101 to 104, a signal bump group 113, and a dummy arranged at the center of the square or a specific signal bump group 114 are arranged. ing.

  The bump groups 114 are arranged in a matrix so as to surround the center of the module substrate 11, have a function of radiating heat generated in the electronic circuit module 1 to the circuit substrate 20, and input / output signals of electronic components are not connected. A dummy or specific input / output signal is connected.

  The signal bump group 113 is arranged in a matrix on the inner peripheral side of the dummy bump groups 105 to 112 of the module substrate 11, and input / output signals of the electronic components of the electronic circuit module 1 are connected to the signal bump group 113.

  The dummy bump groups 105 to 112 to which the input / output signals are not connected are arranged on the long sides 11A and 11B so that the bumps 105A to 112A at the four square corners surround the signal bumps 113A to 113D at the four corners. One row is arranged in a row in the short sides 11C and 11D. And it is not arranged in the fixed range 115-118 of the row direction and the column direction from the center of the long sides 11A and 11B and the short sides 11C and 11D.

  By adopting the above configuration, the dummy bump group 105 has a dimension area of 1/3 or less with respect to the length of one side of the rectangular shape connecting the centers of the long sides 11A and 11B and the short sides 11C and 11D of the module substrate 11. ˜112 are arranged, and the extension ranges 119 on the long sides 11A and 11B and the ranges 115 to 118 related to the extension ranges 120 on the short sides 11C and 11D are not arranged, so that only the minimum necessary bumps are provided. This provides an effect of reinforcing the signal bumps at the corners.

  In this way, by setting the dummy bump groups 105 to 112 to the minimum number of required bumps against the thermal stress generated at the edge of the electronic circuit module, useless bumps can be omitted, and productivity such as materials and processes is improved. It has the effect of clarifying the directionality during mounting and reducing the contact between bumps.

  Next, in the present embodiment, solder connection for protecting signal bumps at the corners of the module substrate unique to the present application, mainly for the purpose of improving reliability, will be described.

FIG. 3 is a view showing a bump arrangement at one corner of the module substrate 11.
A dummy bump group 105 is arranged on the outermost line 101 of the long side 11A, and a dummy bump group 109 is arranged on the outermost line 103 of the short side 11C.

  The signal bump group 113 is arranged at the same pitch 121 in the direction of the long side 11A and the short side 11C inside the dummy bump groups 105 and 109.

  The dummy bump group 105 with the long side 11A is arranged with a pitch 122, and the dummy bump group 109 with the short side 11C is arranged with a pitch 123.

  The pitch of the dummy bump group 105 of the long side 11A and the signal bump group 113 of the outermost periphery is a pitch 125 in the direction of the long side 11A and a pitch 124 in the direction of the short side 11C.

  The pitch of the dummy bump group 109 of the short side 11C and the outermost signal bump group 113 coincides with the pitch 124 in the direction of the long side 11A and zero in the direction of the short side 11C, that is, the center of the signal bump group 113.

  Here, the pitches 121, 122, 123, and 124 are the same, the pitch 125 is ½ of the pitch 121 in the long side 11A direction of the signal bump group 113, and the dummy bump group 105 is a signal bump. It is a so-called staggered arrangement arranged at an intermediate position of the group 113.

  The bumps 113A at the corners of the signal bump group 113 have a pitch 125 in the direction along the long side 11A from the bump 105A closest to the short side 11C in the dummy bump group 105 in the long side 11A, and a pitch 124 in the direction along the short side 11C. In the position.

  On the other hand, among the dummy bump groups 109 of the short side 11C, the bump 109A closest to the long side 11A has a pitch 124 in the direction along the long side 11A from the signal bump 113A and zero in the direction along the short side 11C, that is, the center coincides. In position.

  FIG. 4 is an enlarged view of the arrangement of the dummy bumps 105A, the dummy bumps 109A, and the signal bumps 113A.

  Arrangement of bumps 113A closest to the long side among the bumps 113A at the corners of the signal bump group 113, the bumps 105A closest to the short side among the dummy bump groups 105 of the long side 11A, and the dummy bump groups 109 with the short side 11C. The figure formed by connecting the respective centers is an isosceles triangle 126 having a height equal to the base and close to an equilateral triangle.

  With the above configuration, the signal bump 113A is protected by being surrounded by the dummy bumps 105A and 109A at approximately the same distance, and the corner where the stress is applied is dispersed by two bumps, and the thermal stress is distributed by one bump. Compared to the case, it has the effect of relieving stress. On the other hand, when arranged in a square, the maximum stress is generated in one corner bump. That is, when the bump shapes at the corners of the conventional module substrate are arranged in a square shape, the maximum stress is generated in the corner bumps far from the center, causing the bumps to break.

  In this way, the corner signal bumps 113A where the greatest thermal stress is generated by the heat generation and cooling temperature cycle of the electronic component 12 of the module substrate 11 are surrounded by the long and short dummy bumps 105A and 109A at substantially equal pitches. Thus, stress is relaxed by receiving stress at two corner bumps, that is, dummy bump strength is increased, cracking of signal bumps is prevented, and the reliability of connection between the module substrate 11 and the circuit substrate 20 is improved. This has the effect of improving the overall reliability.

  Further, the number of bumps of the dummy bump groups 105 to 108 having the long sides 11A and 11B is set to be larger than the number of bumps of the dummy bump groups 109 to 112 having the short sides 11C and 11D.

  If it carries out like this, the effect | action which reinforces a longer side with respect to stress can be anticipated. This is because when the midpoint of each of the long and short sides is a fulcrum and the corner where stress is applied is the action point, the long side to which a force is applied from a farther action point is more likely to bend.

  This efficiently protects the periphery of the corner of the long side edge that is more likely to be distorted than the short side, improves the reliability of the connection between the module board 11 and the circuit board 20, and improves the reliability of the entire control circuit. effective.

  In addition, in this embodiment, a further effect can be expected by adopting the following configuration in addition to the configuration specific to the present application.

  The signal bump group 113 and the dummy bump groups 105 to 112 and 114 are formed by a series of forming steps arranged at an equal pitch in terms of design, excluding mechanical errors. In this way, there is little variation in the height of the bumps, and an effect of applying force evenly to all the bumps can be expected, and the reliability of connection between the module substrate 11 and the circuit substrate 20 can be improved. Further, it is possible to improve productivity by unifying the wiring pattern rules of the circuit board. In addition, it has the effect of eliminating the causes such as the inconsistency of bump pitch and solder ball size, which causes a decrease in the production efficiency of the related art, and thus has the effect of improving productivity.

  Regarding the arrangement of the dummy bump groups 105 to 112, a dummy or specific input / output signal bump group 114 is arranged at the center of the module substrate 11. In this way, in addition to heat radiation, there is also an effect of firmly and stably fixing to the circuit board 20, and firmly and stably fixing to the circuit board 20, so that the connection between the module board 11 and the circuit board 20 is reliable. This improves the reliability and improves the reliability of the entire control circuit.

  Since the signal lines are not connected, the outermost dummy bump groups 105 to 112 are arranged up to the edge of the electronic circuit module of the long side and the short side, that is, the outer circumference of the bump diameter coincides with the edge. If it carries out like this, when mounting an electronic circuit module in the circuit board 20, there exists an effect | action which fixes more reliably the outermost periphery of the electronic circuit module which is especially easy to deform | transform by a thermal stress. This reinforces the outermost periphery that is particularly easily deformed during mounting, eliminates the inclination of the circuit board 20 with respect to the module 1, and can evenly distribute the generated thermal stress. In other words, since the tilt is generated, there is no problem that the load is specially applied depending on the bump position and the breakage is accelerated, and the useless bump breakage can be prevented. In addition, the electronic circuit module 1 can be easily handled, and the module substrate 11 and the circuit substrate 20 can be placed in parallel positions, and face-down bonding can be performed by accurate alignment. Therefore, the reliability of the connection between the pads and the bumps can be improved. There is.

  A ball grid array (BGA) electrode connected to the circuit board 20 by a bump employs a transfer molding sealing method suitable for this. In this way, since the resin is injected into the mold with the electronic component 12 mounted on the module substrate 11, there is an effect that the height of the central portion and the edge of the mold of the electronic circuit module 1 become substantially uniform. The module substrate 11 and the circuit board 20 can be aligned in parallel, and there is an effect of ensuring uniform strength of the bumps. On the other hand, in the sealing method in which the resin is dropped from the upper part of the mounting surface of the electronic component 12, the shape of the electronic circuit module 1 after sealing tends to be high at the center and low at the edge due to the fluidity of the resin. . Thereafter, when the pads of the circuit board 20 and the bumps of the module board 11 are aligned while being tilted and connected by a face-down bonding method in which the board is heated, the module board 11 and the circuit board 20 are not parallel to each other. Since the bumps cannot be accurately positioned, the reliability of the connecting portion is inferior, and the above effect cannot be expected.

  Depending on the shape and dimensions of the module substrate 11, the number of bumps of the long-side 11A, 11B dummy bump groups 105-108 and the short-side 11C, 11D dummy bump groups 109-112 is limited to the number of arranged bumps in FIG. It is not something. For example, if the module substrate 11 is square, the dummy bump groups 105 to 112 are arranged with the same number of bumps.

  Moreover, there is no limitation in the sealing method by the mold of the electronic component 12 mounted on the module substrate 11.

<Second Embodiment>
FIG. 5 is a diagram showing another embodiment of the present invention, and the same parts as those in FIG. 1 are denoted by the same reference numerals.

  In FIG. 5, the dummy bump groups 105 to 108 of the long sides 11 </ b> A and 11 </ b> B are aligned with the center of the signal bump group 113, and the dummy bump groups 109 to 112 of the short sides 11 </ b> C and 11 </ b> D are It is arranged in two pitches, so-called staggered arrangement.

  The present embodiment is different in that the arrangement of the dummy bump groups with respect to the signal bump groups on the long side and the short side is reversed from that in FIG.

  Even by adopting the above configuration, the same operations and effects as those of the first embodiment can be obtained.

<Third Embodiment>
FIG. 6 is a diagram showing still another embodiment of the present invention, and the same parts as those in FIG. 1 are denoted by the same reference numerals.

  In FIG. 6, unlike FIG. 2, one dummy bump group 108 on the long side 11B is arranged by one less than the number of bumps on which the other long side dummy bump groups 105, 106, 107 are arranged. There is a feature.

  With the above configuration, basically the same actions and effects as in the first embodiment can be obtained, and the directionality is confirmed in one of the eight dummy bump groups. By providing the mark to be used, there is an effect of preventing erroneous assembly in the step of face-down bonding the electronic circuit module 1 to the circuit board 20.

  In the face-down bonding process, the method for confirming the directivity is not limited to that shown in FIG. 6, and in the arrangement of the dummy bump groups 105 to 112 shown in FIG. If there are, the action and effect are equivalent.

  In FIG. 6, the number of dummy bumps is reduced by one at one location. However, the same effect as described above can be obtained even if the number of dummy bumps is reduced or increased by one or more.

The electronic circuit module mounting diagram of the present invention. The bump arrangement | sequence figure of the module board | substrate which shows one Embodiment of this invention. The bump arrangement figure which expanded a part of one embodiment of the present invention. The bump arrangement figure which expanded the square corner of one embodiment of the present invention. The bump arrangement | sequence figure of the module board | substrate which shows other embodiment of this invention. The bump arrangement | sequence figure of the module board | substrate which shows other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electronic circuit module, 11 ... Module board, 11A, 11B ... Long side of module board, 11C, 11D ... Short side of module board, 12 ... Electronic component, 13 ... Resin mold, 20 ... Circuit board, 21. ..Connection pads, 100 ... Bump group, 105-112 ... Dummy bump group, 113 ... Signal bump, 121 ... Signal bump pitch, 122, 123 ... Dummy bump pitch, 124, 125 ... Pitch between signal bump and dummy bump

Claims (16)

An electronic component circuit board in which electrodes by solder bumps arranged in a grid array are formed on the back surface of a rectangular substrate in which a plurality of electronic components are wired,
Parallel to the sides of the rectangular substrate, signal bumps to which signal lines are connected, and dummy bumps to which signals are not connected to the outer periphery thereof are arranged,
Dummy bumps arranged in parallel to one of opposite each other two sides of the square, the center of the signal bumps arranged in parallel to the two sides facing the other of the rectangle are arranged in including line,
The dummy bumps arranged in parallel with the other two opposite sides of the square are parallel to the dummy bumps arranged in parallel with the two opposite sides of the square and the two opposite sides of the square. electronic component circuit board, characterized in that the center of the signal bumps arranged not arranged including line. The dummy bump including the center of the signal bump is arranged on a line coinciding with the center of the signal bump,
2. The electronic component circuit board according to claim 1, wherein the dummy bumps not including the center of the signal bumps are arranged on an intermediate line of the signal bumps.   The shape connecting the center of each of the signal bumps closest to the four corners of the square substrate and the two dummy bumps closest to the signal bumps is an isosceles triangle having the same height as the base. The electronic component circuit board according to claim 1, wherein the electronic component circuit board is provided.   The dummy bumps are divided into two groups on each side, starting at positions closest to the four corners of the rectangular substrate, and divided into eight groups on all sides. The electronic component circuit board according to claim 1. The dummy bumps are divided into groups of the two places, electrons according to claim 4, characterized in that not arranged in the order of one region of 3 minutes around the middle line of each side of the quadrangle Component circuit board.   6. The electronic component circuit according to claim 4, wherein the dummy bump group divided into eight locations is arranged in such a manner that the number of bumps in one group is different from the number of bumps in another group. substrate.   The electronic component circuit board according to claim 6, wherein the different number is at least one less.   The electronic component circuit board according to claim 6, wherein the different number is at least one more.   The quadrangular substrate has two long sides and two short sides, and the number of bumps of the four dummy bump groups arranged on the long side is smaller than that of the four dummy bump groups arranged on the short side. 6. The electronic component circuit board according to claim 1, wherein the electronic component circuit board is large in number. Bumps number included in the dummy bump group one region, the dummy bump groups at four positions on the long sides, the number of bumps included in dummy bump groups other three of the dummy bump groups at four positions on the long sides The electronic component circuit board according to claim 9, wherein the number is different from that of the electronic component circuit board. The number of bumps to be included in the dummy bump group one region, the dummy bump groups at four positions on the short side, the number of bumps included the in dummy bump groups other three of the dummy bump groups at four positions on the shorter sides The electronic component circuit board according to claim 9, wherein the number is different from that of the electronic component circuit board.   12. The electronic component circuit board according to claim 10, wherein the different number is at least one less.   12. The electronic component circuit board according to claim 10, wherein the different number is at least one more.   14. The electronic component circuit board according to claim 1, wherein the rectangular substrate has a plurality of dummy bumps or signal bumps of specific signals arranged at positions including a center.   The electronic component circuit board according to claim 1, wherein the signal bumps and the dummy bumps are formed at an equal pitch in the same molding process.   16. The electronic component circuit board according to claim 1, wherein the rectangular substrate on which the plurality of electronic components are wired is resin-sealed by transfer molding.

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