JP2013115284A - Metal core printed wiring board, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily suppress generation of voids when the resin of prepreg is filled in through holes of a metal core plate without increasing the number of processes, and to reduce a manufacturing cost.SOLUTION: In a metal core printed wiring board formed by using a metal-clad laminate having insulation layers made of a resin and metal foils in this order from the metal core plate side on both sides of the metal core plate, among the through holes 21 passing through the metal core plate 11 in the thickness direction thereof, a slot 23 having a long portion in which a length in one direction is longer than a length in a direction perpendicular to it includes a resin introducing protrusion 25 for introducing the resin of prepreg laminated by partially protruding in the inward direction perpendicular to the longitudinal direction thereof toward the inside of the long hole on the inner hole surface 24 of the long hole, and the resin is introduced into the long hole 23 to perform filling of the resin.

Description

  The present invention relates to a metal core printed wiring board, and more particularly to a metal core printed wiring board capable of suppressing the generation of voids and a method for manufacturing the same.

  The metal core printed wiring board is manufactured as follows.

  First, in order to obtain a metal core plate, a copper plate having a predetermined thickness is cut to obtain a material, and as shown in FIG. 9, through holes 101 and 102 are drilled at a predetermined position of the material by drilling or etching. A core plate 103 is obtained. Thereafter, the surface of the metal core plate 103 is subjected to a roughening process for improving the adhesion of the resin.

  Next, a prepreg and a copper foil (not shown) are stacked in order from the metal core plate 103 side on both surfaces of the metal core plate 103 after the roughening treatment and heated and pressed, and the metal core plate 103, the prepreg and the copper foil are laminated and integrated. Make it. At the time of this integration, the prepreg resin is filled into the through holes 101 and 102 of the metal core plate 103 as shown in FIG.

  By the lamination and integration, the copper foil 104b exists on both surfaces of the metal core plate 103 via the insulating layer 104a (see FIG. 11). This integrated product is a copper-clad laminate 104 as a metal-clad laminate.

  Subsequently, a hole for a through hole is formed at a predetermined position, and then a necessary process such as through hole plating, pattern formation, solder resist formation, etc. is performed to obtain a metal core printed wiring board.

  However, in the laminated integration by the heating press described above, since the resin in which the prepreg is melted is poured into the through holes 101 and 102, the air that has come out of the prepreg during molding or the air that remains in the draft chamber is changed as shown in FIG. As shown in FIG. 5, the void 105 is often generated by remaining in the resin filled in the through holes 101 and 102. 11A is a cross-sectional view taken along the line AA in FIG. 10 (a cross-sectional view in a direction orthogonal to the longitudinal direction of the through hole 102 formed of a long hole), and FIG. 11B is a cross-sectional view taken along the line BB in FIG. 2 is a longitudinal sectional view of a through hole 102 made of

  If there is a void 105, the electrical characteristics as a wiring board cannot be satisfied, a crack is caused by impact when drilling a through hole, and a thermal cycle in a solder heat resistance test or a reliability test. The voids may expand and contract to cause cracks. For this reason, it is necessary to suppress the generation of voids as much as possible.

  However, even if the processing conditions and the performance of the prepreg are appropriately managed to suppress the generation of voids, it may be difficult to avoid the generation of voids.

  That is, in the design of the substrate, in a portion where a large number of through holes are arranged at a narrow pitch, the through holes are not formed by the circular through holes 101 but are formed by the through holes 102 made of long holes as shown in FIG. However, when a large number of through-holes 102 made of such long holes are arranged in parallel (see the portion A in FIG. 9), voids tend to occur more easily in the through-holes 102 located on the inner side. . This is considered to be due to the fact that there is a limit to the amount of resin that can be impregnated in the prepreg, and it is not possible to secure a sufficient amount of resin to sufficiently and evenly fill through holes that are concentrated.

  As in the case of the metal core printed wiring board disclosed in Patent Document 1 below, if a blocking portion made of resin is previously held in the through hole of the metal core board and an insulating layer is formed on the metal core board, voids are generated. Can be avoided, and there is no shortage of resin.

JP 2009-200289 A

  However, the metal core printed circuit board disclosed in Patent Document 1 requires a step of closing a through hole in manufacturing, which requires labor and manufacturing cost.

  Therefore, the main object of the present invention is to enable the generation of voids to be easily performed without increasing the number of processes and to reduce the manufacturing cost.

  Means for this is a metal core printed wiring board configured by using a metal-clad laminate having an insulating layer and a metal foil made of resin in order from the metal core plate side on both sides of the metal core plate, Of the through-holes penetrating in the thickness direction of the plate, a long hole having a portion whose length in one direction is longer than the length in the direction perpendicular thereto is perpendicular to the longitudinal direction of the inner surface of the long portion. It is a metal core printed wiring board provided with the resin introduction protrusion which guides the resin of the prepreg which protruded partially toward the inside toward the inside of the long hole. The “through hole” includes a slit (through hole) for dividing the core. The through hole having the resin introduction protrusion can be formed by punching with a press.

  In this metal core printed wiring board, the resin introduction protrusion in the long hole of the metal core board partially shortens the distance from the inner surface of the long hole to the center in the width direction of the long hole, and resin is applied to the central part. Guide smoothly. In addition, a part of the long hole is occupied, the volume of the long hole is reduced to reduce the amount of resin required, and the amount of resin supplied to the other through holes is secured.

  The resin introduction protrusion may have a substantially triangular shape that becomes narrower toward the tip side. It is possible to equalize the distance from the inner surface of the resin introduction protrusion to the farthest center in the width direction of the long hole, to reduce the difference in filling time and to promote smooth filling. The “substantially triangular shape” means that a triangle is included.

  The tip of the resin introduction protrusion may have a corner rounded portion. Generation of burrs is suppressed, and smoothness of resin filling can be secured.

  Another means is a metal core plate that has a through hole penetrating in the thickness direction and constitutes a metal core printed wiring board, and the length of one direction of the through hole in a direction perpendicular to the metal core plate. A long hole having a portion longer than the length guides the resin of the prepreg laminated and partially protruding toward the inside perpendicular to the longitudinal direction on the inner surface of the long portion toward the inside of the long hole. It is a metal core board provided with the resin introduction protrusion.

  Another means is a metal-clad laminate using this metal core plate.

  Still another means is a method of manufacturing a metal core printed wiring board configured by using a metal-clad laminate having an insulating layer made of a resin and a metal foil in order from the metal core board side on both sides of the metal core board. Of the through-holes penetrating in the thickness direction of the metal core plate, a long hole having a portion whose length in one direction is longer than the length in a direction perpendicular thereto is formed on the inner surface of the long portion. It is formed by punching with a press so as to have a resin introduction protrusion that partially protrudes inwardly perpendicular to the direction, and in the laminating process by laminating the metal core plate, prepreg and metal foil at the subsequent stage The method of manufacturing a metal core printed wiring board in which the resin of the prepreg is guided inward of the elongated hole and the elongated hole is filled with the resin.

  As described above, according to the present invention, the resin introduction protrusion of the metal core plate partially shortens the distance from the inner surface of the long hole to the center in the width direction of the long hole, and is a portion far from the inner surface of the hole. Since the resin flow into the resin is promoted, the resin can be smoothly filled in the long holes and the generation of voids can be suppressed. In addition, the amount of resin required for filling is suppressed, and even in a portion where a plurality of elongated holes are densely arranged, the amount of resin filled in the elongated holes is ensured, so voids are also generated in this portion. Can be suppressed. As a result, a good quality product can be obtained stably.

  Moreover, it is only necessary to form the resin introduction protrusion in the through hole of the metal core plate, and furthermore, the resin introduction protrusion can be formed simultaneously with the formation of the through hole, so that the number of steps is not increased and the productivity is good. . For this reason, the manufacturing cost can also be reduced.

The top view of a metal core board. Explanatory drawing of the manufacturing process of a metal-clad laminated board and a metal core printed wiring board. The top view of a long hole. The top view of a long hole. The top view of a long hole. The top view of a long hole. Explanatory drawing of a lamination | stacking integration process. Sectional drawing of a metal-clad laminate. The top view of the conventional metal core board. The partially broken top view of the conventional metal tension laminate sheet. AA sectional drawing and BB sectional drawing of FIG.

  An embodiment for carrying out the present invention will be described below with reference to the drawings.

  In this invention, as shown in FIG. 1 and FIG. 2, the purpose of suppressing the generation of voids can be easily performed without increasing the number of steps, and the manufacturing cost can be reduced. Among the through holes 21 penetrating in the thickness direction of the metal core plate 11, the inner surface 24 of the long portion of the long hole 23 having a length in one direction longer than the length in the direction orthogonal thereto is This is realized by a configuration including a resin introduction protrusion 25 that guides the resin of the prepreg 14 that partially protrudes toward the inner side perpendicular to the longitudinal direction toward the inner side of the long hole 23.

  FIG. 1 is a plan view of a part of the metal core plate 11, and FIG. 2 is an explanatory diagram of the manufacturing process of the copper clad laminate 12 and the metal core printed wiring board 13 using the metal core plate 11.

  First, the manufacturing process of the metal core printed wiring board 13 is demonstrated easily using FIG.

  A copper plate having a predetermined thickness is cut into a predetermined shape with a predetermined size to obtain a material 11a of the metal core plate 11 (see FIG. 2A). And the through-hole 21 penetrated to the thickness direction based on the design of a board | substrate is drilled with respect to the predetermined position of this raw material 11a (refer FIG.2 (b)). In this drilling step, as shown in FIG. 1, a circular (dotted) through-hole 22 having a circular shape in plan view and a long-hole-like (linear) through-hole 23 having a linear shape in plan view (hereinafter referred to as “ A through hole 21 having a required shape and dimension is formed.

  Thereafter, the surface of the metal core plate 11 having the necessary through holes 21 is subjected to a roughening process for improving the adhesion of the resin, and then the process proceeds to the lamination and integration step (see FIG. 2C). .

  In the lamination and integration step, the prepreg 14 and the copper foil 15 are sequentially stacked on both surfaces of the metal core plate 11 from the metal core plate 11 side, and sandwiched between pressure plates (not shown), and heated and pressed in a vacuum environment. The resin in which the prepreg 14 is melted is filled in the through holes 21 of the metal core plate 11 by the heating press and covers both surfaces of the metal core plate 11. As a result, the resin of the metal core plate 11 and the prepreg 14 and the copper foil 15 are integrated to obtain the copper-clad laminate 12 as a metal-clad laminate in which an insulating layer 14a made of resin is formed (FIG. 2D). reference).

  Subsequently, a through-hole 16 is formed at a predetermined position (see FIG. 2 (e)), through-hole plating 17 (see FIG. 2 (f)), pattern 18 formation (see FIG. 2 (g)), solder resist When the necessary processing such as forming 19 (see FIG. 2H) is performed, the metal core printed wiring board 13 is obtained.

Next, the metal core plate 11 will be described.
As shown in FIG. 1, the metal core plate 11 has at least the circular through hole 22 and the long hole 23. The circular through holes 22 are formed in a predetermined arrangement with a predetermined size. The long hole 23 has a portion in which the length in one direction is longer than the length in the direction orthogonal thereto, and has a shape extending in a straight line, for example, as shown in FIG. Like the circular through-holes 22, they are formed in a predetermined arrangement with a predetermined size. The long hole 23 may be a long hole having a bent part or a partially or entirely curved long hole in addition to the straight line shape as described above. In addition to the above, a slit-like through hole for dividing the core may be used.

  The long hole 23 shown in FIG. 3 (a) has a portion in which the length in one direction is longer than the length in the direction perpendicular to the elongated hole 23, that is, the hole inner surface 24 in the entire longitudinal direction. A plurality of resin introduction protrusions 25 that partially protrude toward the surface are provided. The resin introduction protrusion 25 guides the resin of the prepreg 14 toward the inside of the long hole 23 in the lamination and integration step.

  The resin introduction protrusion 25 in FIG. 3A is formed in a substantially triangular shape that is sandwiched between two arc-shaped sides and becomes narrower toward the tip side, and is opposed to the direction perpendicular to the longitudinal direction of the long hole 23. In this state, they are arranged at equal intervals. This arrangement interval w is set as appropriate, but is shorter than the length a in the direction orthogonal to the longitudinal direction of the long hole 23 (hereinafter referred to as “width direction”) and longer than half the length a. It is good that it is w. Preferably, the interval is slightly shorter than the length a. With such a distance w, when the resin introduction protrusion 25 is formed with an arc having the same curvature as that when both ends of the elongated hole 23 are formed in a circular shape with the same curvature as shown in the drawing, It is possible to make the distance from the inner surface 24 of the circular arc shape with respect to the intersection point p between the center point between the resin introduction protrusions 25 in the longitudinal direction and the center in the width direction substantially equal.

  Due to the resin introduction protrusion 25, the elongated hole 23 has a portion with a short length in the width direction in the longitudinal direction. That is, the volume of the long hole 23 is smaller than when it is assumed that there is no resin introduction protrusion 25 and the hole inner surface 24 of the long hole 23 is linear in the entire longitudinal direction. Moreover, the hole inner surface 24 of the long hole 23 has a planar view shape that is intertwined in the width direction, and is longer in distance from the hole inner surface 24 than when assuming an equidistant portion from the inner surface of the oblong hole. The portions do not extend linearly in the longitudinal direction of the elongated hole, but are scattered in the longitudinal direction. For this reason, a portion having a long distance from the hole inner surface 24 can be reduced, and variation in the distance from the hole hole surface 24 can be suppressed due to the substantially triangular shape of the resin introduction protrusion 25.

  Further, the tip of each resin introduction protrusion 25 may be pointed as shown in FIG. 3B, but it is preferable to include a corner radius portion 25a as shown in FIG. By providing the corner rounded portion 25a, it is possible to suppress the occurrence of defects such as burrs when the long hole 23 is formed.

  Such circular through holes 22 and long holes 23 can be formed with a drill or the like in the drilling step (see FIG. 2B), but a press using a mold (not shown). It is formed by punching.

  The shape, arrangement, size, and the like of the resin introduction protrusion 25 are appropriately set according to the design of the substrate. A few examples of the resin introduction protrusion 25 can be configured as shown in FIGS. 4, 5, and 6, for example.

  In other words, the resin introduction protrusion 25 shown in FIG. 3 has a shape such that a virtual circular hole is continuously formed in a partially overlapping state, but when formed in such a shape, As shown in FIG. 4A and FIG. 4B, the protrusion of the resin introduction protrusion 25 is caused by the distance b between the centers of the virtual circular holes with respect to the length a in the direction orthogonal to the longitudinal direction of the long hole 23. The length c is determined. That is, as the distance b between the centers of the virtual circular holes is longer than the length a in the direction orthogonal to the longitudinal direction, the length c of the resin introduction protrusion 25 is formed longer as shown in FIG. it can.

  Depending on the design of the substrate, as shown in FIG. 4C, the distances b and d between the centers of the virtual circular holes may be partially different. In this case, of course, there is a difference in the protrusion length c of the resin introduction protrusion 25, but the discharge length c is indicated by a virtual line in FIG. 4C by changing the size of the corner radius portion 25a. In addition, it can be shortened.

  Further, the corner rounded portion 25 a at the tip of the resin introduction protrusion 25 can be set larger than the width of the base portion of the resin introduction protrusion 25. FIG. 5A shows the gap between the bases of the resin introduction protrusions 25 having the corner radius portions 25a set to be large via a hole inner surface 24a that is linear in the longitudinal direction of the long hole 23. It is an example of the shape of the elongated hole 23 made continuous. FIG. 5B shows the shape of the long hole 23 in which the bases of the resin introduction protrusions 25 are connected via a hole inner surface 24b having an arc shape with the same curvature as the corner radius part 25a of the resin introduction protrusion 25. It is an example.

  Further, as shown in FIG. 6A, the resin introduction protrusion 25 is extended from the base in a triangular shape so as to become narrower toward the distal end side, and the distal end is formed into a square shape so that the substantially comb teeth as a whole. It can also be formed into a shape. The resin introduction protrusions 25 may be formed in a simple rectangular plate shape and spaced apart in a substantially comb shape. Although illustration is omitted, in this case as well, it is preferable to form a corner radius portion.

  Furthermore, as shown in FIG. 6B, it is also possible to arrange the resin introduction protrusions 25 in a zigzag pattern without facing each other in the direction orthogonal to the longitudinal direction.

  When the lamination integration process is performed using the metal core plate 11 having the above-described configuration, the resin of the prepreg 14 in a state of being stacked on the metal core plate 11 is melted as shown in FIG. As shown, the resin flows into all the through holes 21 including the long holes 23.

  At this time, in the long hole 23, the resin introduction protrusion 25 guides the resin of the prepreg 14 to the inside of the long hole 23 and fills the long hole 23 with resin.

  Since the resin introduction protrusion 25 of the long hole 23 partially occupies the inside of the long hole 23, the volume of the long hole 23 is reduced, and the amount of resin flowing in can be reduced. In addition, the resin introduction protrusion 25 partially reduces the distance from the hole inner surface 24 of the elongated hole 23 to the center in the width direction of the elongated hole 23 and linearly distributes the portion where the distance from the hole inner surface 24 is long. Instead of letting it be scattered. In addition, the distance can be equalized, and the resin is smoothly guided to the central portion in the width direction of the long hole 23 away from the hole inner surface 24, so that the time difference required for filling is reduced. As a result, sufficient filling of the resin is performed quickly.

  Further, since the volume of the long hole 23 is reduced to reduce the amount of resin to be filled, even if the through hole 21, especially a plurality of the long holes 23 are arranged side by side, Of course, the resin supply amount to other through holes 21 is secured. The material cost of the prepreg can also be reduced.

  Furthermore, since the tip of the resin introduction protrusion 25 has a rounded corner 25a, as a result of suppressing the occurrence of burrs during the drilling process as described above, the resin flow is prevented from being disturbed. Smoothness of resin flow during resin filling can be improved.

  For this reason, as shown to Fig.8 (a) and FIG.8 (b), the copper clad laminated board 12 without a void is obtained. FIG. 8A is a cross-sectional view in a direction orthogonal to the longitudinal direction of the long hole, and FIG. 8B is a cross-sectional view in a direction along the longitudinal direction of the long hole.

  Therefore, the copper-clad laminate 12 having no voids can be obtained, the quality can be improved, and the quality can be stabilized. In addition, since there is no increase in the number of processes, the productivity can be greatly improved while suppressing the cost in combination with the improvement in quality and the stability thereof.

  Further, the long hole 23 is formed by punching with a press. Since the inner surface 24 of the hole has a plurality of resin introduction protrusions 25 along the longitudinal direction, stress due to the press during the drilling process is relieved, and the long hole 23 is formed. Since the surface rigidity in the opposing part which pinches | interposes increases, it has the advantage that curvature can be suppressed and it contributes to the improvement of quality. In addition, compared to drilling or the like, the above-described drilling can be performed with a single action, so that a metal core plate with stable quality can be mass-produced.

  Furthermore, since the resin introduction protrusion 25 has the corner rounded portion 25a as described above, it is possible to relieve the concentrated stress generated during the press processing and to secure a clearance than when the tip is sharpened. The durability of the mold can be obtained. Also from this point, mass production is possible and the cost can be reduced.

In correspondence between the configuration of the present invention and the configuration of the one aspect,
The metal foil of the present invention corresponds to the copper foil 15,
Similarly,
The metal-clad laminate corresponds to the copper-clad laminate 12,
The present invention is not limited to the above configuration, and other forms can be adopted.

  For example, you may use things other than copper foil for metal foil.

  In addition, all the portions of the long hole may not be composed of a portion whose length in one direction is longer than the length in a direction orthogonal thereto, and may be a long hole having the long portion in part. In addition, the resin introduction protrusion is not formed over the entire long hole, but is formed in the long portion.

DESCRIPTION OF SYMBOLS 11 ... Metal core board 12 ... Copper clad laminated board 13 ... Metal core printed wiring board 14 ... Pre-preg 14a ... Insulating layer 15 ... Copper foil 21 ... Through-hole 23 ... Long hole 24 ... Hole inner surface 25 ... Resin introduction part 25a ... Square radius Part

Claims (6)

A metal core printed wiring board configured using a metal-clad laminate having an insulating layer and a metal foil made of resin in order from the metal core plate side on both sides of the metal core plate,
Of the through-holes penetrating in the thickness direction of the metal core plate, a long hole having a portion in which the length in one direction is longer than the length in the direction perpendicular thereto is formed on the inner surface of the long portion in the longitudinal direction. A metal core printed wiring board provided with a resin introduction protrusion that guides the resin of the prepreg laminated so as to partially protrude toward the inner side perpendicular to the inner side toward the inner side of the elongated hole. The metal core printed wiring board according to claim 1, wherein the resin introduction protrusion has a substantially triangular shape that becomes narrower toward the tip side. The metal core printed wiring board according to claim 1, wherein a tip of the resin introduction protrusion has a corner rounded portion. A metal core plate having a through hole penetrating in the thickness direction and constituting a metal core printed wiring board,
Among the through holes, a long hole having a portion whose length in one direction is longer than the length in a direction perpendicular thereto is partially formed on the inner surface of the long portion toward the inside perpendicular to the longitudinal direction. A metal core plate provided with a resin introduction protrusion that guides the resin of the prepreg that protrudes and is laminated toward the inside of the elongated hole. A metal-clad laminate using the metal core plate according to claim 4. A method for producing a metal core printed wiring board configured by using a metal-clad laminate having an insulating layer and a metal foil made of resin in order from the metal core plate side on both surfaces of the metal core plate,
Of the through-holes penetrating in the thickness direction of the metal core plate, a long hole having a portion in which the length in one direction is longer than the length in the direction perpendicular thereto is formed on the inner surface of the long portion in the longitudinal direction. Punched with a press so as to have a resin introduction protrusion that partially protrudes inwardly perpendicular to
A metal core printed wiring board in which the metal core plate, the prepreg, and the metal foil are laminated in a subsequent stage, and the resin of the prepreg is guided to the inside of the elongated hole and the elongated hole is filled with the resin in a laminating step by a hot press. Manufacturing method.

Images