JP2011198910A - Insulated heat dissipation substrate, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an inexpensive and reliable junction of an insulated heat dissipation substrate in a simple process.SOLUTION: The insulated heat dissipation substrate includes: a lead frame 9 formed by punching predetermined conductor patterns 9a, 9b, 9c, 9d and covering the top surface side thereof with resist 10; and an insulating resin layer 11 arranged with the lead frame 9 with the surface of the resist 10 being exposed, wherein a peeling section 13 is provided on a part of the top surface of the lead frame 9 by peeling the resist 10 off and forming an unevenness on a bottom surface and a soldering section is formed in the peeling section 13.

Description

  The present invention relates to an insulating heat dissipation substrate used for various electronic devices and a method for manufacturing the same.

  Hereinafter, a conventional method for manufacturing an insulated heat dissipation substrate will be described with reference to the drawings. FIG. 10 is a perspective view of a conventional insulating heat radiating substrate 1 in which a resist 5 for preventing a solder flow or the like covering a conductor pattern 4 disposed on the surface of an insulating layer 3 provided on a metal plate 2 is partially provided. The conductor exposed portion 6 that can be removed by soldering and enables soldering or the like is formed. Here, for example, to form the conductor exposed portion 6, first, as a first step, a resist 5 that completely covers the conductor pattern 4 shown in the perspective view of FIG. 11, which is in a state before forming the conductor exposed portion 6, is formed. A mask 8 having a hole 7 corresponding to a portion where the resist 5 is to be removed is overlaid on the insulated heat dissipation substrate 1 and then a solvent such as an etching solution is poured into the hole 7 of the mask 8 as a second step. Thus, the resist 5 corresponding to the exposed conductor portion 6 as shown in FIG. 10 corresponding to the shape of the hole 7 is peeled off, and then the mask 8 is insulated as a third step as shown in FIG. In this case, unnecessary solvent is removed by washing in a state where they are superposed on each other or in a state where they are separated from each other, and this is achieved by combining these steps.

  As prior art document information relating to the invention of this application, for example, Patent Document 1 and Patent Document 2 are known.

JP-A-9-18143 Japanese Patent Laid-Open No. 7-171689

  However, as shown in FIG. 11, in the conventional method for manufacturing an insulating heat dissipation substrate, a solvent is used to remove the resist 5, so that it is difficult to strictly define the amount of the solvent in the hole 7 of the mask 8, For this reason, even at one peeling site, the depth of peeling over the entire peeled area is lacking in stability and uniformity, and there is a possibility of lack of reliability when soldering in later mounting. In particular, when the conductor exposed portion 6 is formed to secure a land for mounting a device in which the electrode to be joined has a very small dimension, the dimension of the peeling of the resist 5 in the micro area is a dimension. There was a problem that it was very difficult to maintain accuracy. Further, in the production process, complicated and many steps such as substrate cleaning, drying, resist printing, curing, masking, etching, water cleaning, hot water cleaning, and drying are required, and there is a problem that productivity is lowered.

  Accordingly, an object of the present invention is to make it possible to form an inexpensive and highly reliable joint with a simple process.

  In order to achieve this object, a lead frame formed by punching a predetermined conductor pattern and covering the upper surface side with a resist, and an insulating resin layer in which the lead frame is disposed with the resist surface exposed. And a solder welded portion is formed on the peeled portion after providing a peeled portion having a concavo-convex portion formed on the bottom surface by peeling the resist on a part of the top surface of the lead frame. It is.

  According to the present invention, it is possible to form a highly reliable joint by a simple process.

The perspective view of the insulated heat dissipation board | substrate in the 1st Embodiment of this invention 1st partial sectional view of an insulating heat dissipation board in a first embodiment of the present invention The 1st partial top view of the insulated heat dissipation board | substrate in the 1st Embodiment of this invention FIG. 3 is a state diagram of the surface of the insulating heat dissipation board in the first embodiment of the present invention The 2nd fragmentary sectional view of the insulated heat dissipation board in a 1st embodiment of the present invention. The 3rd fragmentary sectional view of the insulation heat dissipation board in the 1st embodiment of the present invention. The 2nd partial top view of the insulation heat dissipation board in the 1st embodiment of the present invention The fragmentary perspective view of the manufacturing method of the insulated heat dissipation board in the 2nd Embodiment of this invention The 1st partial top view of the insulated heat dissipation board | substrate in the 2nd Embodiment of this invention First perspective view of a conventional insulated heat dissipation substrate Second perspective view of a conventional insulated heat dissipation substrate

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a perspective view of an insulating heat dissipation board according to the first embodiment of the present invention. A lead frame 9 formed by punching predetermined conductor patterns 9a, 9b, 9c, 9d is covered with a resist 10 on the upper surface side. Then, the resist 10 is exposed on the upper surface, and the lower surface side of the lead frame 9 is disposed or attached to the upper surface side of the insulating resin layer 11. Here, the metal heat radiating plate 12 is disposed in contact with the lower surface side of the insulating resin layer 11, but the metal heat radiating plate 12 may be disposed and applied as necessary.

  Here, a peeling portion 13 from which the resist 10 has been peeled is formed on a part of the upper surface of the lead frame 9. Then, as shown in the first partial cross-sectional view of the insulated heat-radiating substrate in FIG. 2, an uneven portion 14 is formed on the bottom surface of the peeling portion 13, and a solder weld portion 15 is formed on the peeling portion 13. Here, a connection terminal of an electronic component which is a connected object (not shown) is connected.

  According to this configuration, the peeling portion 13 is a state in which, for example, copper or a copper alloy itself, which is a conductor constituting the lead frame 9, is exposed without the resist 10 being present, The wettability is very good. Then, the area where the lead frame 9 and the solder welded portion 15 are joined can be obtained by the uneven portion 14, and as a result, the anchoring effect between the lead frame 9 and the solder welded portion 15 and the reliability thereof. In addition, the electrical resistance of the joint portion can be kept small.

  Further, as shown in the first partial top view of the insulating heat dissipation substrate in FIG. 3, the concavo-convex portion 14 provided on the bottom surface of the peeling portion 13 is formed so that the convex portion 17 is isolated and discontinuous in the concave portion 16. It doesn't matter. Thereby, the area where the lead frame 9 and the solder welded portion 15 obtained by the concavo-convex portion 14 shown in FIG. 2 are joined can be further increased, and the fixing property and its reliability can be further improved. It is.

  Furthermore, as shown in FIG. 3, it is desirable that the uneven portions 14 are regularly arranged in a lattice pattern. As a result, the anchor effect obtained by the concavo-convex portion 14 is generated almost uniformly over the entire surface of the peeling portion 13, so that the fixing property is also averaged. In other words, it is possible to avoid a situation in which reliability is deteriorated due to concentration of mechanical deterioration due to partial stress.

  Here, as for the cross section of the concavo-convex portion 14, the shape shown in FIG. 2 in which the width of the concave portion 16 is large and the width of the convex portion 17 is small is given as an example. The width of the convex portion 17 may be increased. These may be selected according to the energy distribution of the laser light irradiation region, for example, if the unevenness portion 14 is formed by laser light irradiation.

  The measured value of the cross section when the concavo-convex portion 14 is formed by the laser beam is as shown in the state diagram of the surface of the insulating heat dissipation substrate in FIG. 4, and the concavo-convex value on the top surface side with respect to the resist surface is the resist formation region. It is clear that the unevenness is small and the unevenness is large in the resist peeling side region. Here, the resist is a very thin oxide film (approximately 2 μm), and the unevenness in the resist peeling side region has a larger value than the oxide film. In this example, a resist with a very small value and the depth of the peeled portion are shown. However, the effects described so far are not limited to those with a small value, and may be in units of mm. Absent.

  In the above description, the lead frame 9 is disposed on the upper surface of the insulating resin layer 11, and the resist 10 covers both the insulating resin layer 11 and the lead frame 9. It is shown that the peeling part 13 is provided in the part. On the other hand, a lead frame 9 that is particularly thick and is required to be formed by punching is applied. As shown in the second partial cross-sectional view of the insulating heat dissipation substrate in FIG. It is desirable to embed on the upper surface side and to arrange only the upper surface side of the lead frame 9 exposed from the insulating resin layer 11.

  As a result, heat received from a heat generating component (not shown) via the solder welded portion 15 can be transmitted to the insulating resin layer 11 not only from the lower surface of the lead frame 9 but also from the side surface having a thickness. The efficiency can be improved. Of course, it is also possible to improve the adhesion between the lead frame 9 and the insulating resin layer 11. Further, since the resist 10 and the insulating resin layer 11 exist outside the peeling portion 13, even if the amount is inappropriate when the solder welded portion 15 is formed, the solder flow This is effective for the stability of the mounting, because there are double regions, adjacent to each other in terms of positional relationship, and discontinuous materials. In particular, the resist 10 is made of an oxide film formed in advance on the copper surface of the lead frame 9 without applying an imide-based resin, or a silicon compound or a fluorine compound such as an oxide film and a release agent attached on the oxide film. When the remaining state is applied, when the resist 10 made of an oxide film or the like is embedded in the insulating resin layer 11 together with the lead frame 9, the resist 10 made of an oxide film or the like is the minimum necessary only on the surface of the lead frame 9. Can be secured, and at the same time, the thickness is very thin and the thickness is not easily uneven. Therefore, the above-described effect of preventing the flow and the upper surface side of the resist 10 and the upper surface side of the insulating resin layer 11 are the same. It becomes easy to make a flat surface without a step, and stable mounting can be easily ensured for mounting of a device (not shown).

  Here, in order to form the resist 10 made of an oxide film on the surface of the lead frame 9, for example, the lead frame 9 having an oxide film generated in an unoxidized state or left at room temperature is firstly formed with the insulating resin layer 11. Then, the insulating resin layer 11 in which the lead frame 9 is embedded may be heated and cured, and the oxide film may be formed by oxidizing only the portion where the lead frame 9 is exposed by the heating. When embedding the lead frame 9 in the insulating resin layer 11, the upper surface of the lead frame 9 exposed from the insulating resin layer 11 and the upper surface of the insulating resin layer 11 are made substantially the same surface, and the exposed portion is oxidized in that state. ing. Therefore, the exposed oxide film on the upper surface of the lead frame 9 becomes a thicker oxide film than the unexposed part, and has a sufficient function as a barrier against solder. In addition to this, although there is a strict difference between the exposed oxide film on the upper surface of the lead frame 9 and the upper surface of the insulating resin layer 11, it is much more compared with the case where the resist 10 is formed of resin. It is a small value and can be regarded as substantially the same plane, and does not affect the mountability of a device (not shown). In addition, the above-described release agent is often performed in a molding die when the lead frame 9 is embedded in the insulating resin layer 11, and in that case, the insulating resin layer 11 and the die are easily peeled off. For this purpose, a release agent is applied. And when it is taken out from the mold after molding, a silicon compound or fluorine compound, which is a mold release agent, is adhered on the oxide film, and this mold release agent is also used in the bonding process because of its mold release property. Has a function as a barrier against further solder. At the same time, it is not necessary to remove the release agent by washing or the like in the pre-process of soldering.

  In the above description, the resist 10 and the insulating resin layer 11 are doubled as a region for preventing the solder flow. However, as shown in the third partial cross-sectional view of the insulating heat dissipation substrate in FIG. 13 and the insulating resin layer 11 may be in a positional relationship adjacent to each other. Here, the insulating resin layer side surface portion 18 corresponding to the side surface portion of the insulating resin layer 11 in contact with the peeling portion 13 is in a state of standing substantially perpendicularly from the upper surface side to the lower surface side of the insulating resin layer 11, so that the solder welded portion Since the layer functions as a wall that prevents the flow of the film when the layer 15 is formed, a layer having a resist function may not be interposed. Accordingly, as shown in the second partial top view of the insulating heat dissipation substrate in FIG. 7, the lead frame 9 and the insulating resin layer 11 are not located on the lead frame 9 at a position separated from the insulating resin layer 11. The contact portion 19 can be formed in contact with each other, and the degree of freedom with respect to the arrangement of the peeling portion 13 is increased.

  At the same time, as shown in FIG. 6, the peeling side surface portion 20 corresponding to the side surface portion of the peeling portion 13 in the lead frame 9 is also standing substantially perpendicularly from the upper surface side to the lower surface side of the lead frame 9. Thereby, even if the width dimension W of the peeling part 13 is a small value, for example, the uneven part 14 is efficiently formed over the entire surface of the width dimension W. As a result, the adhesion of the solder welded part 15 is improved. Can be improved. As a matter of course, since a large fixing strength can be obtained by a narrow region, this also enables downsizing of the entire insulating heat dissipation substrate.

(Second Embodiment)
Next, the formation method of the peeling part 13 demonstrated so far is demonstrated. FIG. 8 is a partial perspective view relating to a method for manufacturing an insulating heat dissipation substrate. In an insulating heat dissipation board formed by forming an insulating resin layer 11 on a metal heat radiating plate 12 and embedding a lead frame 9 which is a conductor formed in an arbitrary pattern with a conductor on the upper surface of the insulating resin layer 11, at least a lead The resist 10 covering the surface of the frame 9 is irradiated with laser light 21 having a predetermined wavelength from the laser light irradiation port 22, thereby forming the peeling portion 13 from which the resist 10 has been removed.

  As a result, the conductor portion of the lead frame 9 is exposed at the peeling portion 13 to improve the wettability of solder and the like, and an electronic component (not shown) is mounted by joining with the solder or the like at the peeling portion 13 later. Can be easily done. Needless to say, the solder at that time stays only at the peeling portion 13 and does not flow out to the region where the resist 10 exists. In addition, since the irradiation position of the laser beam 21 can be set very strictly with respect to the irradiation position, the range from the peeling area 13 having a small area to the peeling area 13 having a large area is accurate regardless of the size of the area. The dimension can be set. Furthermore, when the release agent has a function as the resist 10, it is not necessary to remove the release agent by washing or the like in a pre-process of soldering.

  Here, the laser beam 21 to be irradiated determines the output depending on the wavelength at which reaction inherent to the material is likely to occur and the depth required by the peeling portion 13, and at the same time, the irradiation diameter is set. The removal of the copper oxide formed on the surface of the lead frame 9 made of copper alloy as an example is taken as an example for the first purpose, and therefore a constant suitable for the removal of this copper oxide is set. At this time, the lead frame 9 has a very high temperature heat due to the irradiation of the laser beam 21, but the lead frame 9 is buried and insulated after being in close contact with the insulating resin layer 11 with a part thereof exposed. Since it is applied as a heat dissipation substrate, the heat generated in the lead frame 9 is immediately transmitted to the insulating resin layer 11 to be dissipated. Therefore, the lead frame 9 itself is not easily deformed by heat, and a stable shape can be maintained, and electronic components (not shown) can be mounted in a stable state. Further, the lead frame 9 is desirably of a level having a thickness that can be embedded as described above (approximately 0.2 mm or more), that is, a thickness enough to form the lead frame 9 in a predetermined pattern by punching. .

  Next, the locus of the laser light 21 irradiation method will be described with reference to the first partial top view of the insulating heat dissipation substrate shown in FIG. By individually forming strip-shaped strips A1 to C2 having a specific width LW in the irradiated portion of the laser with respect to the lead frame 9 embedded in the insulating resin layer 11 and covered with the resist 10, A peeling portion 13 having a predetermined area is formed.

  For example, here, as the first stage, the separation band A1 (solid line) is formed by laser irradiation. Then, as the second stage, a separation band B1 (broken line) is similarly formed by laser irradiation. At this time, laser irradiation is performed in a state where the separation band A1 (solid line) and the separation band B1 (broken line) partially overlap without forming a gap. Hereinafter, similarly, the laser irradiation is performed in the order of the peeling band C1 (one-dot chain line), the peeling band A2 (solid line), the peeling band B2 (dashed line), and the peeling band C2 (one-dot chain line), thereby finally removing the peeling portion 13. Forming.

  Further, here, when comparing the vicinity of the center of the stripping band and the vicinity of both ends, the irradiation energy is larger in the vicinity of the center. For example, the depth at which the resist 10 is removed in the same stripping band A1 (solid line) is It is deep near the center and shallow near both ends. Since this naturally occurs in all of the strips A1 to C2, in the X-X 'cross section, the cross section of the peel portion 13 has an uneven shape as shown in FIG. 9 have the same irradiation power, irradiation width, and irradiation time, the peeling depth in the unit area is almost the entire area in the width W direction of the peeling portion 13 shown in FIG. It is the same, and the u region near both ends and the v region near the center in the width W direction are not shallow or deep.

  When the solder welded portion 15 is formed later by the method for forming the peeled portion 13 described above, the bonding area is increased due to the presence of the concavo-convex portion 14, and as a result, the bonding strength can be increased. Further, since the peeling depth in the unit area is almost the same in the entire area in the width W direction, the strength distribution of the solder welded portion 15 is less varied, and the reliability of the solder welded portion 15 can be improved. .

  Further, when the separation bands A1 to C2 shown in FIG. 9 formed here are defined as the horizontal direction, laser irradiation may be performed so that a vertical separation band (not shown) is added also in the vertical direction. At this time, since removal of the resist 10 has been completed on the entire surface by the strips A1 to C2 in the stripping section 13, the longitudinal strips may be arranged in parallel after having a predetermined interval instead of overlapping trajectories. .

  As a result, the top view of the peeling portion 13 has a form in which the convex portions 17 are arranged in a lattice pattern as shown in FIG. 3, thereby further increasing the surface area of the peeling portion 13 and further increasing the bonding strength. It is something that can be done.

  Here, the strips A1 to C2 shown in FIG. 9 and the longitudinal strip (not shown) have been described as linear continuous strips, but they are not strip-like trajectories caused by continuous laser irradiation. The strip-shaped strips A1 to C2 having a constriction or a longitudinal strip (not shown) may be formed by intermittently performing circular or elliptical irradiation. In this case, the concavo-convex shape of the part peeled off at the peeling portion 13 becomes more complex than that obtained by continuous laser irradiation, and the increase in surface area due to the concavo-convex shape becomes large. Accordingly, it is possible to further improve the reliability of the solder welded portion 15 accompanying the increase of the uneven portion 14 shown in FIG.

  In laser irradiation, since the power value is variable, the degree of peeling is increased at high power at predetermined intervals by moving the irradiation spot at a constant speed and changing the predetermined power value. It becomes possible to do. Naturally, it is possible to form strips with irregularities of various widths and depths depending on the power value and the moving speed, and the pitch between the stripped band and other strips is narrowed by slowing the irradiation spot moving speed. If the irradiation spots are overlapped, a deep uneven peeling band is formed. If the irradiation spot is accelerated, a shallow uneven peeling band can be formed with a wide interval between the peeling band and another peeling band.

  In addition, as shown in FIG. 7, since the laser wavelength at which the resist 10 and the insulating resin layer 11 are likely to react is different, the laser wavelength can be changed between the lead frame 9 side and the insulating resin layer 11 side of the boundary portion 19, It is not necessary to irradiate the laser exactly along the boundary 19, and by irradiating the laser simultaneously or continuously on both sides of the boundary 19 so as to straddle the lead frame 9 side and the insulating resin layer 11 side. You may apply to the process of irradiation. As a result, as shown in FIG. 6, the peeling depths of the peeling portion 13 in contact with the insulating resin layer side surface portion 18 on the insulating resin layer 11 side and the peeling portion 13 on the peeling side surface portion 20 side are made to coincide with each other. In addition, since the formation by laser irradiation is performed, the insulating resin layer side surface portion 18 and the peeled side surface portion 20 can be formed in a substantially vertical shape.

  For these reasons, the strength distribution of the solder welded portion 15 is also less varied, and the reliability of the solder welded portion 15 can be improved.

  The insulated heat dissipation board of the present invention has an effect of enabling formation of a highly reliable joint, and is useful in applying the insulated heat dissipation board to various electronic devices.

DESCRIPTION OF SYMBOLS 9 Lead frame 9a Conductor pattern 9b Conductor pattern 9c Conductor pattern 9d Conductor pattern 10 Resist 11 Insulating resin layer 12 Metal heat sink 13 Peeling part 14 Concavity and convexity part 15 Solder welding part 16 Concave part 17 Convex part 18 Insulating resin layer side part 19 Boundary part 20 Peeling side

Claims (12)

A lead frame formed by punching a predetermined conductor pattern, and its upper surface side covered with a resist;
An insulating resin layer on which the lead frame is disposed with the resist surface exposed;
On the part of the top surface of the lead frame, after providing a peeling portion that peels off the resist and forms an uneven portion on the bottom surface,
An insulated heat dissipation board in which a solder weld is formed on the peeled portion. The insulating heat dissipation substrate according to claim 1, wherein the resist is formed of an oxide film. The insulating heat-radiating substrate according to claim 1, wherein the resist is formed of an oxide film and a silicon compound or a fluorine compound that covers the oxide film. The insulating heat dissipation substrate according to any one of claims 1 to 3, wherein the uneven portions are arranged in a lattice pattern. A lead frame formed by punching a predetermined conductor pattern, and its upper surface side covered with a resist;
An insulating resin layer in which the lead frame is embedded by exposing the resist surface;
On the part of the top surface of the lead frame, after providing a peeling portion that peels off the resist and forms an uneven portion on the bottom surface,
An insulated heat dissipation board in which a solder weld is formed on the peeled portion. The insulating heat dissipation substrate according to claim 5, wherein the resist is formed of an oxide film. 6. The insulating heat dissipation substrate according to claim 5, wherein the resist is formed of an oxide film and a silicon compound or a fluorine compound covering the oxide film. The insulating heat dissipation substrate according to any one of claims 5 to 7, wherein the uneven portions are arranged in a grid pattern. The insulating heat dissipation substrate according to any one of claims 5 to 7, wherein the peeling portion is formed in contact with a boundary portion between the lead frame and the insulating resin layer. The insulated heat-radiating substrate according to claim 5, wherein the lead frame has a thickness of 0.2 mm or more. A lead frame formed by punching a predetermined conductor pattern and covering the upper surface side with a resist,
The resist surface is exposed and placed on the insulating resin layer,
A part of the upper surface of the lead frame is provided with a peeling portion from which the resist is peeled, and a solder weld is formed on the peeling portion.
In the peeling step for providing the peeling portion,
The said peeling part is a manufacturing method of the insulated heat dissipation board | substrate formed by irradiating a laser to the said resist. The peeling process is performed by laser irradiation.
A first peeling step for forming a plurality of longitudinal peeling grooves in a straight line;
The manufacturing method of the insulated heat dissipation board | substrate of Claim 11 which consists of a 2nd peeling process which forms several horizontal direction peeling groove | channel linearly.

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