JP2003324283A - Multilayer printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer printed wiring board which can easily perform pressure bonding to laminated layers and surely obtain connection between upper and lower boards. <P>SOLUTION: This multilayer printed wiring board is formed by pressure- bonding laminated layers of a first board 1 and a second board 2. The first board 1 includes a first insulating board 17 and a first via hole 14. The second board 2 includes a second insulating board 27 and a second conductor layer 23 connected to the first via 14 or/and a second via 24. The first insulating board 17 and the second insulating board 27 are formed of thermosetting resins. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board capable of surely conducting electrical connection between upper and lower sides.

[0002]

2. Description of the Related Art A multilayer printed wiring board is formed by laminating a plurality of insulating substrates each having a conductor layer formed thereon. Each conductor layer is electrically connected through the via. When manufacturing a multilayer printed wiring board, as shown in FIG. 8, a thermosetting resin is prepared as an insulating substrate 97, and a via 94 is formed therein. Then, the conductor 95 is filled in the via 94.
Next, the conductor pattern 93 is formed by the additive method or the subtractive method. By the above, a plurality of substrates 91, 92 for stacking are obtained. Next, an adhesive sheet 96 made of prepreg is prepared, and a hole 960 is formed in a portion corresponding to a via joint portion between the substrates. Next, the substrates 91 and 92 are laminated via the adhesive sheet 96 and pressure-bonded.
As a result, an integrated multilayer printed wiring board is obtained.

[0003]

However, in the above-described conventional method for manufacturing a multilayer printed wiring board, the thermosetting resin forming the insulating substrate 97 is already thermoset at the time of stacking and pressure bonding. Therefore, in order to bond the insulating substrates to each other, it is necessary to interpose the adhesive sheet 96 therebetween, which is troublesome. Further, since the insulating substrate 97 is already hardened and hard, it is difficult to follow the shape of the opposing substrate surfaces when laminated.
The conductor 95 in the via 94 is also hard. Therefore, as shown in FIG. 9, the concavo-convex state of the joint surface 90 of the substrates 91 and 92 after crimping is the same as that before crimping. Therefore, an imbalance in the adhesive force may occur at the bonding surface 90 of the substrate, and a defective adhesion portion may occur. In particular, the tip portion of the conductor 95 in the via 94 cannot project into the hole 960 of the adhesive sheet 96, and the void 99 remains, which may cause a conduction failure between the vias 94.

In view of the above-mentioned conventional problems, the present invention is to provide a multilayer printed wiring board which can be easily laminated and crimped and can be surely connected between the upper and lower sides of the substrate.

[0005]

The present invention is directed to a first substrate having a first insulating substrate and a first via, a second insulating substrate, and a second conductor layer or / and a second via connected to the first via. A multilayer printed wiring board characterized in that the first insulating substrate and the second insulating substrate are made of a thermoplastic resin by laminating and pressure-bonding a second substrate having the above.

In the multilayer printed wiring board of the present invention, the first and second insulating substrates are made of thermoplastic resin, and therefore exhibit flexibility when heated. For this reason, the first and second insulating substrates shrink in the direction of pressure applied during lamination pressure bonding. On the other hand, since the first via is made of a hard conductor, it does not shrink due to the pressure applied during lamination pressure bonding. Therefore, at the time of stacking and pressure bonding, the first via protrudes slightly from the first and second insulating substrates and is surely connected to the second via or the second conductor layer, so that the electrical continuity between the upper and lower sides is ensured. The first and second insulating substrates are
Since they are laminated and pressure-bonded by following the concavities and convexities on the surface of the other substrate facing each other, a gap is unlikely to occur between the two. Therefore, the pressure bonding strength is increased, cracks are less likely to occur between the substrates, and moisture intrusion can be suppressed. First made of thermoplastic resin,
The second insulating substrate is softened by heat during lamination pressure bonding, the conductors arranged above and below are reliably joined, and the second insulating substrate can be bonded to the substrate without an adhesive.

Further, the thermoplastic resin softens at a lower temperature than the conductive material used for the via, the conductor layer and the like. Therefore, by heating the insulating substrate made of thermoplastic resin at a temperature higher than the softening temperature and lower than the melting temperature of the conductive material, it is possible to soften only the insulating substrate without melting the conductive material. it can. Therefore, the insulating substrate can be easily separated from the conductive material such as the conductor layer and the via. The thermoplastic resin is softened without decomposition by heating at a temperature slightly higher than that. Therefore, when the multilayer printed wiring board is discarded or recycled, resin decomposition components are less likely to be generated and air pollution can be suppressed.

According to the present invention, it is possible to provide a multilayer printed wiring board which can be easily laminated and pressure-bonded and which can reliably connect the upper and lower sides of the substrate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, it is preferable that the thermoplastic resin used for the first and second insulating substrates is not cured but is used while maintaining the thermoplasticity. This is because if the resin used for the insulating substrate hardens, recycling will be hindered.

The softening temperature of the thermoplastic resin is 200 ° C.
The above is preferable (claim 2). Multilayer printed wiring boards may be slightly heated during manufacture and use. Also in this case, if the softening temperature is 200 ° C. or higher, the insulating substrate does not deform. On the other hand, if the temperature is lower than 200 ° C, the insulating substrate may be deformed during manufacture and use. It is desirable that the thermoplastic resin does not deform under no load at 260 ° C. for 1 minute. As a result, deformation during manufacturing and use can be further suppressed. Examples of the thermoplastic resin include PEEK (polyether ether ketone), PES (polyether sulfone), and PEI.
(Polyether imide), PEK (polyether ketone), PPE (polyphenyl ether) and the like.

There are various forms of the first via in the present invention. The softening temperature of the thermoplastic resin is preferably 200 ° C. or higher (claim 3). This is because the metal piece is a solid body, and thus has a large bonding area with the second via and the second conductor layer of the other party at the time of crimping and has excellent connection strength.

A metal piece is preferably embedded in the first via (claim 4). Since this metal-plated column is also a solid body, it has excellent connection strength with the second via and the second conductor layer during crimping.

It is preferable that a metal plated column is deposited in the first via (claim 5). Also in this case, it is possible to connect to the second via and the second conductor layer of the partner. In this case, it is preferable to plug the inside of the first via. This is to prevent the cavity from remaining in the via.

A metal plating film is preferably formed on the wall surface of the first via (claim 6). Also in this case, the second via and the second conductor layer can be connected.
The conductive resin preferably comprises a thermosetting resin and a metal filler. This is because the thermosetting resin is hardened by heating, so that the connection with the second via and the second conductor layer of the other party becomes reliable. The thermosetting resin is, for example, epoxy resin, and the metal filler is, for example, copper fiber.

The second via can also take various forms like the first via. It is preferable that the first via and the second via or the second conductor layer are bonded by a conductive adhesive such as solder or silver paste. This makes the connection between the two more reliable. When the conductor of the first via or the second via itself is solder or silver paste, the conductor itself serves as an adhesive, so that it is not necessary to separately use the conductive adhesive as described above. The first board and the second board are relative names of the boards in the multilayer printed wiring board. A plurality of first substrates and second substrates may be laminated in one multilayer printed wiring board.

[0016]

EXAMPLES The embodiments of the present invention will be described in more detail with reference to examples. (Embodiment 1) As shown in FIG. 1, a multilayer printed wiring board of this embodiment has a second substrate 2 on the upper and lower side surfaces of a first substrate 1.
Are laminated and pressure-bonded. The first substrate 1 has a first insulating substrate 17, a first via 14, and a first conductor layer 13. The second substrate 2 has a second insulating substrate 27, and a second conductor layer 23 and a second via 24 provided at the same position as the first via 14 on the surface thereof. Both the first insulating substrate 17 and the second insulating substrate 27 are made of PEEK as a thermoplastic resin. The first via 14 and the second via 24 have a metal piece 51.
Is embedded.

Next, in manufacturing the multilayer printed wiring board of this embodiment, as shown in FIG.
A first via 14 is drilled in. On the other hand, a metal foil 50 having substantially the same thickness as that of the first insulating substrate 17 is prepared, and both upper and lower surfaces thereof are covered with a thin solder film 60. Copper is used as the metal foil 50. Next, the metal foil 50 coated with the solder film 60 is placed on the first insulating substrate 17, and these are placed on the punching die 8. A punch 81 for punching is provided on the punching die 8, and the punch 8 is provided directly below the punch 81.
A guide hole 80 through which 1 can be inserted is opened. Then,
As shown in FIG. 3, the metal foil 50 is punched by the punch 81, and the punched metal piece 51 is embedded in the first via 14. The solder layer 6 in which the solder film 60 is punched is formed on the upper and lower ends of the punched metal piece 51. Then, the conductor layer 13 for the inner layer is formed and patterned. The first substrate 1 is obtained as described above.

Next, the second substrate 2 is manufactured by the same method as described above. However, no pattern is formed on the uppermost conductor layer at this point. Then, FIG.
As shown in FIG. 2, the second substrate 2 is laminated on both upper and lower sides of the first substrate 1, and these are applied with a pressure of 1.96 Pa and a heating temperature of 2.
Crimping at 50 ° C for 20 minutes. At this time, the solder layer 6 covering the end of the metal foil 51 is melted and bonded to the other via or conductor layer. Moreover, since the first insulating substrate 17 and the second insulating substrate 27 are made of thermoplastic resin, they adhere to each other without leaving a gap by following the surface shape of the other insulating substrate at the time of pressure bonding. As described above, the multilayer printed wiring board shown in FIG. 1 is obtained.

In the multilayer printed wiring board of this example, since the first and second insulating substrates 17 and 27 are made of thermoplastic resin, they show flexibility when heated. For this reason, the first via 14 slightly protrudes from the first and second insulating substrates 17 and 27 at the time of stacking and pressure bonding, and is reliably connected to the second via 24 or the second conductor layer 23 so that the vertical conduction is maintained. Be certain. Also, first,
Since the second insulating substrates 17 and 27 are laminated and pressure-bonded following the unevenness of the surface of the other substrate facing each other, a gap is unlikely to occur between them. Therefore, the pressure bonding strength is increased, cracks are less likely to occur between the substrates, and moisture intrusion can be suppressed.

Further, the thermoplastic resin softens at a lower temperature than the metal material used for the conductor layer. Therefore, by heating the first and second insulating substrates 17 and 27 made of a thermoplastic resin at a temperature higher than their softening temperature and lower than the melting temperature of the conductor layer, the insulating layer is not melted. Only can be softened. Therefore, the insulating substrate can be easily separated from the conductor layer. The thermoplastic resin is softened without decomposition by heating at a temperature slightly higher than that. Therefore, when the multilayer printed wiring board is discarded or recycled, resin decomposition components are less likely to be generated and air pollution can be suppressed.

(Embodiment 2) In the multilayer printed wiring board of this embodiment, as shown in FIG. 5, the second substrate 2 is laminated and pressure-bonded under the first substrate 1. A conductive resin 52 is filled in the first and second vias 14 and 24. The conductive resin 52 is composed of an epoxy resin material which is a thermosetting resin and copper fibers as a metal filler. First via 14 and second via 2
The joint surface side end of 4 is covered with a solder layer 6.
Others are the same as in the first embodiment.

In this example, the first and second vias 14 and 2 are
4 is filled with a conductive resin 52 containing a thermosetting resin. The thermosetting resin is hardened by the heat applied during lamination pressure bonding. Since the end portions of the first and second vias 14 and 24 on the joint surface side are covered with the solder layer 6, the solder layer 6 is melted by the heat at the time of stacking and pressure bonding and both vias are bonded. Since the first and second insulating substrates 17 and 27 are made of a thermoplastic resin, they can be bonded to each other without an adhesive and can be recycled as in the case of the first embodiment without leaving a gap between them.

(Embodiment 3) In this embodiment, as shown in FIG. 6, metal plating columns 53 are deposited in the first and second vias 14 and 24. One end of each of the first and second vias 14 and 24 is previously covered with the first and second conductor layers 13 and 23, and electrolytic copper plating is performed in this state. Then, metal plating is deposited from the surface of the conductor layer covering the via, and eventually reaches the via opening end. As a result, the metal plating pillar 53 is formed. Then, the head of the metal-plated pillar 53 is coated with the solder layer 6 by solder plating. As described above, the first and second vias 14 and 24 are formed. Others are the same as those in the second embodiment. Also in this example, the first and second vias 14 and 24 are surely connected as in the second embodiment, and the adhesive strength between the first and second substrates 1 and 2 is also high.

(Embodiment 4) In this embodiment, as shown in FIG. 7, the metal plating film 54 is formed on the first and second vias 14 and 24.
Are formed. The metal plating film 54 is formed by depositing copper by an electroless or electrolytic method. First and second via 14,
The inside of 24 is plugged with a thermosetting resin 55. The first and second conductor layers 13 and 23 at the peripheral portions of the first and second vias 14 and 24 are covered with the solder layer 6. During lamination pressure bonding, the solder layers 6 electrically connect the conductor layers. Others are the same as those in the second embodiment. Also in this example, the same effect as in Example 2 can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a multilayer printed wiring board according to a first embodiment.

FIG. 2 is an explanatory diagram showing a method of embedding a metal piece in a first via according to the first embodiment.

FIG. 3 is an explanatory view showing a method of embedding a metal piece, following FIG. 2;

FIG. 4 is an explanatory diagram showing a stacking method of the first and second substrates in the first embodiment.

FIG. 5 is a cross-sectional view of the multilayer printed wiring board of Example 2.

FIG. 6 is a sectional view of a multilayer printed wiring board according to a third embodiment.

FIG. 7 is a sectional view of a multilayer printed wiring board according to a fourth embodiment.

FIG. 8 is an explanatory view showing a method for laminating a multilayer printed wiring board in a conventional example.

FIG. 9 is an explanatory diagram showing a problem in the conventional example.

[Explanation of symbols]

1. ． ． First substrate, 2. ． ． Second substrate, 6. ． ． Solder layer, 8. ． ． Punching die, 13. ． ． First conductor layer, 14. ． ． First via, 17. ． ． First insulating substrate, 23. ． ． Second conductor layer, 24. ． ． Second via, 27. ． ． Second insulating substrate, 50. ． ． Metal foil, 60. ． ． Solder film, 80. ． ． Guide hole, 81. ． ． punch,

Claims (6)

[Claims] 1. A first substrate having a first insulating substrate and a first via, a second insulating substrate, and a second substrate having a second conductor layer or / and a second via connected to the first via. A multilayer printed wiring board, characterized in that the first insulating substrate and the second insulating substrate are made of a thermoplastic resin. 2. The multilayer printed wiring board according to claim 1, wherein the softening temperature of the thermoplastic resin is 200 ° C. or higher. 3. The multilayer printed wiring board according to claim 1, wherein a metal piece is embedded in the first via. 4. The multilayer printed wiring board according to claim 1, wherein metal plating columns are deposited in the first via. 5. The multilayer printed wiring board according to claim 1, wherein a metal plating film is formed on a wall surface of the first via. 6. The multilayer printed wiring board according to claim 1, wherein the first via is filled with a conductive resin.