Patent Application
20140299367
The present invention relates to a component-embedded substrate manufacturing method for embedding electrical or electronic components in a substrate and a component-embedded substrate manufactured using the same.
Recently, with increased density of components mounted on the surface of an electronic circuit board, that is, enhanced functionality of the electronic circuit board, attention has been paid to a component-embedded substrate having a structure in which electronic components are embedded in an insulating substrate serving as an insulating layer. A wiring pattern is formed on the surface of the insulating substrate of the component-embedded substrate. The component-embedded substrate on the surface of which other various electronic components are mounted at a predetermined position of the wiring pattern can be used as a module board. In addition, the component-embedded substrate can also be used as a core board for use in manufacturing a component-embedded multilayer circuit board by a buildup method.
The aforementioned component-embedded substrate requires an electrical connection between the wiring pattern and the terminals of the electronic components in the insulating substrate. It has been known to use soldering for the connection (for example, see Patent Document 1).
In the meantime, several surface mounting processes of various electronic components are performed in the process of manufacturing the module board or the multilayer circuit board. In general, reflow soldering is performed for the surface mounting of the electronic components. Each time an electronic component is mounted on the surface, the component-embedded substrate is placed in a reflow furnace and is heated to a temperature at which the solder melts. Therefore, the connection portions inside the insulating substrate in the component-embedded substrate disclosed in Patent Document 1 are heated to a solder melting temperature several times, which may reduce the reliability of the connection portions.
In light of this, in order to improve the reliability of the connection portions in the component-embedded substrate, it has been known to provide electrical connections between the connection portions inside the insulating substrate by copper plating instead of solder plating (for example, see Patent Document 2). Specifically, the melting point of the copper is higher than the melting point of the solder, and thus the component-embedded substrate placed in the reflow furnace does not allow the connection portions to melt, thereby maintaining the reliability of the connection portions.
The detail of the manufacture method disclosed in Patent Document 2 is described below.
First, a lamellar body is formed by laminating an insulating layer on a metal layer such as a copper foil. Then, a guide hole is formed in the lamellar body, and further a connection hole is formed in the lamellar body using the guide hole as a reference. The connection hole is formed in an intra-substrate component region to be arranged on the insulating layer. In a later step, copper is filled in the connection hole. The filled copper forms a metal joint for electrically connecting the wiring pattern to the terminal of the intra-substrate component. Subsequently, an adhesive is applied to the region and the adhesive is used to fix the intra-substrate component on the insulating layer. At this time, the intra-substrate component is positioned using the connection hole. Here, the intra-substrate component is positioned so that the terminal thereof corresponds to the connection hole. Note that the adhesive flows into the connection hole.
Then, an insulating base material such as a prepreg to serve as the insulating substrate is laminated on the insulating layer of the lamellar body. At this point, the insulating substrate having the intra-substrate component buried in the insulating base material is formed. The obtained insulating substrate has the metal layer of the lamellar body located on one surface thereof and the connection hole is opened in an outer surface of the metal layer. In this state of the insulating substrate, the adhesive inside the connection hole is removed from the outer surface side of the metal layer to expose the terminal of the intra-substrate component inside the connection hole. Then, the entire outer surface of the metal layer including the connection hole is subjected to a copper plating process. This causes copper to grow and fill the connection hole so as to electrically connect the metal layer positioned on the surface of the insulating substrate to the terminal of the intra-substrate component. Subsequently, part of the metal layer on the surface of the insulating substrate is etched to form a wiring pattern and thereby to form a component-embedded substrate.
Unfortunately, the aforementioned manufacturing method has a problem that when the adhesive for fixing the intra-substrate component is applied to the region, part of the adhesive flows into the connection hole as described above, resulting in reduction in thickness of the adhesive layer, which may cause the following troubles.
First, a commonly used adhesive contains a filler to maintain the strength of the adhesive layer after the adhesive is cured. However, an adhesive layer with a thickness less than the size of the filler may cause the filler to easily fall off from the adhesive layer and hence a required strength may not be obtained.
Note that the adhesive layer is also used as the insulating layer. Thus, when the adhesive layer is too thin, it may be difficult to ensure the required insulating properties.
Therefore, a low viscosity adhesive or a low thixotropy adhesive which tends to flow into the connection hole is not suitable for the aforementioned manufacturing method, and hence the available adhesive is limited.
It is an object of the invention, which has been made in view of the above circumstances, to provide a component-embedded substrate manufacturing method capable of positioning and forming a connection hole for use in electrically connecting a terminal of an embedded component to a wiring pattern with a good accuracy and widening the range of choice of an adhesive for fixing the component; and a component-embedded substrate manufactured using the same.
In order to attain the above object, the present invention provides a method of manufacturing a component-embedded substrate which includes an electrical or electronic component embedded in an insulating substrate having a wiring pattern on a surface thereof and in which a terminal of the component is electrically connected to the wiring pattern, the method comprising: a metal layer forming step of forming a metal layer on a support plate, the metal layer including a first surface contacting the support plate and a second surface opposite to the first surface, and the second surface having a mounting expected region for the component and a non-mounting region other than the mounting expected region; a mark forming step of forming a metal main mark in the non-mounting region of the second surface; a seat forming step of forming a metal seat in the mounting expected region of the second surface simultaneously with the formation of the main mark, the metal seat having a central through-hole; an adhesive applying step of applying an insulating adhesive to the mounting expected region and the seat to thereby form an adhesive layer, the adhesive layer having a filling region in a position of the central through-hole of the seat, and the filling region filling the inside of the central through-hole with the adhesive; a component mounting step of mounting the component on the adhesive layer in a state in which the component is positioned using the main mark as a reference and the terminal of the component contacts the filling region; a buried layer forming step of forming a buried layer serving as the insulating substrate for burying the component and the main mark on the second surface; a separation step of separating the support plate from the metal layer to expose the first surface of the metal layer by the separation thereof; a window forming step of removing part of the metal layer from the exposed first surface side and thereby forming a first window for exposing at least the main mark and a second window for exposing at least the central through-hole of the seat respectively in the metal layer; a via hole forming step of determining the position of the terminal of the component using the exposed main mark as a reference, removing the adhesive of the filling region filling the inside of the through-hole of the exposed seat, and thereby forming a via hole reaching the terminal in the filling region; a conductive via forming step of subjecting the via hole to a plating process, then filling metal in the via hole and the second window, and thereby forming a conductive via for electrically connecting between the terminal and the metal layer; and a pattern forming step of forming the metal layer into the wiring pattern.
Here, a preferred aspect of the component-embedded substrate manufacturing method is that in the mark forming step, a metal sub mark in a non-mounting region of the second surface is formed simultaneously with the main mark; between the separation step and the window forming step, the method further comprises a through-hole mark forming step of determining the sub mark using X-rays and thereby forming a through-hole mark penetrating all of the metal layer, the sub mark, and the buried layer; and in the window forming step, the first window and the second window are formed using the through-hole mark as a reference.
In addition, a preferred aspect is that the main mark, the sub mark, and the seat are formed by pattern plating using a plating resist film.
In addition, the present invention provides a component-embedded substrate manufactured using the above described component-embedded substrate manufacturing method.
Here, a preferred aspect is that the component-embedded substrate further comprises the sub mark and the through-hole mark.
According to the component-embedded substrate manufacturing method of the present invention, the electrical or electronic component is positioned using the main mark formed on the metal layer; and the via hole formed in a later step is formed by removing resin inside the central through-hole of the seat formed simultaneously with the main mark. In other words, the position of the formed via hole is the same as that of the central through-hole of the seat. Accordingly, the position of the component determined using the main mark formed simultaneously with the seat is the same as the position determined using the seat, that is, the via hole. Thus, the via hole for electrically connecting the component to the terminal of the component can be positioned with extremely high accuracy.
In addition, according to the present invention, the seat formed simultaneously with the main mark serves as a spacer for ensuring a space between the component and the metal layer (wiring pattern), and hence can maintain a constant thickness of the adhesive layer between the component and the metal layer. As a result, an adhesive layer having excellent adhesive strength and insulating properties can be stably obtained. Moreover, the seat has a central through-hole, and the position of the central through-hole matches the position of the terminal of the component to be mounted. Thus, the via hole can be formed at the exact position as designed by removing the filling region of the adhesive layer inside the central through-hole.
In addition, according to the component-embedded substrate manufacturing method of the present invention, the component is mounted on the metal layer with an adhesive interposed therebetween and then the adhesive is cured to obtain the adhesive layer. The metal layer does not have a hole to be preliminarily drilled therein, which prevents uncured adhesive from falling down in the hole. This enables the obtained adhesive layer to have a required thickness and can ensure the adhesive strength and the insulating properties as designed. In other words, the present invention widens the range of choice of the adhesive.
Further, according to the present invention, the mark forming step forms the sub mark simultaneously with the main mark; and before the window forming step, the method comprises a through-hole mark forming step of determining the sub mark using X-rays and thereby forming a through-hole mark penetrating all of the metal layer, the sub mark, and the buried layer. If the through-hole mark is used as a reference, the position of the main mark hidden in the metal layer and the position corresponding to the terminal of the component can be easily determined, and hence the first window and the second window can be easily formed.
In addition, according to the present invention, the main mark, the sub mark, and the seat are formed by pattern plating using a plating resist film, and thus can be easily formed in a printed circuit board manufacturing facility which has been commonly used heretofore. Therefore, the present invention contributes to improving production efficiency of the entire component-embedded substrate.
In addition, the component-embedded substrate of the present invention is obtained by the above described manufacturing method and hence has an extremely high accuracy of positioning between the embedded component and the wiring pattern and a low rate of occurrence of defective products.
There follows a description of a procedure for manufacturing a component-embedded substrate having an electronic component (hereinafter referred to as an intra-substrate component) 14 embedded in an insulating substrate by applying a component-embedded substrate manufacturing method of the present invention thereto.
According to the present invention, first, a metal layer is formed on a support plate (metal layer forming step).
As illustrated in
Next, a seat made of a copper annular body is formed simultaneously with the mark forming step of forming a positioning mark made of a copper columnar body on the copper-clad steel plate 6 (seat forming step).
More particularly, as illustrated in
The position of arranging the mark 12 can be arbitrarily selected in a non-mounting region N, but preferably is a position that can be easily recognized by an optical sensor of an optical positioning apparatus (unillustrated) for positioning the intra-substrate component 14 to be embedded in the insulating substrate. According to the present embodiment, as illustrated in
Meanwhile, the positions of arranging the seats 60 each are set to a terminal position t which is inside the mounting expected region S and at which the terminal 20 of the intra-substrate component 14 is to be positioned so that the central through-holes 62 face each other.
Next, the adhesive 16 is supplied to the mounting expected region S (adhesive applying step).
First, as illustrated in
As is clear from
The above described adhesive 16 is cured to be an adhesive layer 18 with a predetermined thickness. The obtained adhesive layer 18 fixes the intra-substrate component 14 in a predetermined position and has predetermined insulating properties. The adhesive 16 is not particularly limited as long as the adhesive exhibits a predetermined adhesive strength and predetermined insulating properties after it is cured, but the examples thereof include an adhesive having a filler added to a ultraviolet curable epoxy-based resin or polyimide-based resin, an adhesive having a filler added to a thermosetting epoxy-based resin or polyimide-based resin, and the like. Examples of the filler include a fine powder such as silica (silicon dioxide) and a glass fiber. The present embodiment uses a low-viscosity adhesive having a fine powder of silica added to a thermosetting epoxy-based resin.
Next, the intra-substrate component 14 is mounted on the copper-clad steel plate 6 with the adhesive 16 interposed therebetween (component mounting step).
First, as illustrated in
Next, insulating base materials are laminated to bury the intra-substrate component 14, the inside marks A and B, and the outside marks C and D (buried layer forming step).
First, as illustrated in
Thereby, the uncured-state thermosetting resin of the prepreg is pressurized and filled in a gap of the through-hole 30 and the like, and then is cured by the heat of the hot pressing. As a result, as illustrated in FIG. 6, an insulating substrate 34 including the insulating base materials 22 and 24 is formed and the intra-substrate component 14 is buried in the insulating substrate 34. Here, the through-hole 30 is preliminarily provided in the insulating base material 22 (see
Then, as illustrated in
The present step separates the support plate 2 from the first metal layer 4 to expose the first surface 3 of the first metal layer 4 by the separation. Thus, an intermediate 40 of the component-embedded substrate is obtained. The intermediate 40 includes the insulating substrate 34 having the intra-substrate component 14 therein; the first metal layer 4 formed on one surface (lower surface) 36 of the insulating substrate 34; and the second metal layer 28 formed on the other surface (upper surface) 38 thereof.
Next, windows are formed in the obtained intermediate 40 by removing a predetermined portion of the first metal layer 4 (window forming step).
First, as illustrated in
Subsequently, the reference holes 42 are used as the references to determine a portion in which the inside marks A and B are located and a portion in which the seats 60 are located (hereinafter referred to as a seat location portion) T. Then, for each determined portion, part of the first metal layer 4 is removed from the first surface 3 of the first metal layer 4 by a commonly used etching process. This forms a first window W1 for exposing part of the insulating substrate 34 together with the inside marks A and B; and a second window W2 for exposing a portion of the adhesive layer 18 including the seat location portion T. At this time, as illustrated in
Next, the filling region 63 of the adhesive layer 18 inside the central through-hole 62 of the seat 60 is removed to form a via hole in the filling region 63 (via hole forming step).
First, the exposed inside marks A and B are recognized by an optical sensor of an optical positioning apparatus (unillustrated). Then, the positions of the inside marks A and B are used as the references to determine the position of the terminal 20 of the intra-substrate component 14 hidden in the adhesive layer 18. Subsequently, the determined terminal position is irradiated with laser such as carbon dioxide laser to remove the filling region 63 of the adhesive layer 18 so as to expose the terminal 20 of the intra-substrate component 14. The laser is emitted in a certain width of irradiation range R and can remove the adhesive layer 18 in the irradiation range R.
According to the present invention, the position of the terminal 20 of the intra-substrate component 14 matches that of the central through-hole 62 of the seat 60, and hence the laser is emitted to the lower end surface of the seat 60 including the central through-hole 62. This removes the filling region 63 of the adhesive layer 18 inside the central through-hole 62, resulting in that the central through-hole 62 is formed into a laser via hole (hereinafter referred to as an LVH) 46 reaching the terminal 20 (
As is clear from the above described embodiment, the present invention is characterized in that the inside marks A and B are used not only to position the intra-substrate component 14 but also to form the LVH 46 again. Thus, the present invention can exhibit an extremely high accuracy of positioning and hence can form the LVH 46 at an accurate position relative to the terminal 20 hidden in the adhesive layer 18.
Next, a plating process is applied to the intermediate 40 in which the LVH 46 is formed, and then copper is filled in the LVH 46 to form a conductive via for electrically connecting between the terminal 20 of the intra-substrate component 14 and the first metal layer 4 (conductive via forming step).
First, a copper electroless plating process is applied to the inside of the first window W1 and the second window W2 including the inside of the LVH 46. Thereby, the surfaces of the insulating substrate 34 and the adhesive layer 18 partially exposed through the first window W1 and the second window W2, the inner wall surface of the LVH 46, and the surface of the terminal 20 of the intra-substrate component 14 are covered with copper. Subsequently, a copper electroplating process is applied to grow a copper plating layer 48 covering the entire first metal layer 4 including the inside of the LVH 46 as illustrated in
Next, parts of the first metal layer 4 and the second metal layer 28 on the surface of the insulating substrate 34 are removed to form a predetermined wiring pattern 50 (pattern forming step).
The parts of both of the metal layers 4 and 28 are removed by a common etching process. This forms a component-embedded substrate 1 incorporating the intra-substrate component 14 having the terminal 20 electrically connected to the wiring pattern 50 in the insulating substrate 34 having the predetermined wiring pattern 50 on the surface thereof as illustrated in
The present invention does not preliminarily drill a hole in the metal layer 4 of the mounting expected region S and hence prevents the adhesive from falling down to the lower side of the metal layer 4. Therefore, various adhesives including low-viscosity adhesives can be used.
Thus obtained component-embedded substrate 1 can be used as a module board by mounting other electronic components on the surface thereof. In addition, the component-embedded substrate 1 can also be used as a core board to form a multilayer circuit board by a commonly used buildup method.
Note that the above described embodiments use both of the inside mark A and the inside mark B as the marks for positioning the intra-substrate component 14 and the LVH, but the present invention is not limited to these embodiments. For example, another embodiment may use only one of the inside mark A and the inside mark B as the marks for positioning the intra-substrate component 14 and the LVH. The present invention is characterized by using the same mark to determine the terminal position when the intra-substrate component is positioned and the LVH is provided, and hence even the use of only one of the inside mark A and the inside mark B can exert sufficiently high positioning accuracy. The above description has focused on embodiments using both of the inside mark A and the inside mark B as preferred embodiments of more improving the positioning accuracy.
Note that the present invention is not limited to the embodiments of providing the positioning marks near the mounting expected region S, but the positioning marks may be provided at a portion far away from the mounting expected region S. For example, the embodiment of providing the positioning mark at a portion far away from the mounting expected region S is used when a plurality of component-embedded substrates (pieces) are made in a large-size workpiece. More particularly, the workpiece is a substrate having a large frame portion on a peripheral thereof and a plurality of sheets are formed inside the large frame portion. Each sheet has a small frame portion on a peripheral thereof and a plurality of pieces are formed inside the small frame portion. Finally, each piece is cut away to obtain an individual component-embedded substrate. In such a workpiece, for example, the main mark (inside mark) is formed in the small frame portion and the sub mark (outside mark) is formed in the large frame portion. As described above, in the large-size workpiece, the main mark and the sub mark (positioning mark) are formed at a portion far away from the piece (mounting expected region S) such as the large frame portion and the small frame portion described above; and these marks are used as the references to determine the position of the component and the position of the terminal when the LVH is provided.
Note that the component embedded in the insulating substrate is not limited to the packaging component, but the present invention may embed other various electronic components such as chip components.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2011/075705 | 11/8/2011 | WO | 00 | 4/30/2014 |
