A wiring substrate having no core substrate includes a build-up layer including insulating layers and conductor layers such that the insulating layers include first, second, third and fourth insulating layers and that the conductor layers include a first conductor layer formed on the first insulating layer and a second conductor layer formed on the second insulating layer. The build-up layer has a first surface having the first insulating and first conductor layers, a second surface having the second insulating and second conductor layers, the third insulating layer formed on the first insulating layer on the opposite side of the first conductor layer, and the fourth insulating layer formed on the second insulating layer on the opposite side of the second conductor layer, and the build-up layer is formed such that the first and second insulating layers contain no core material and the third and fourth insulating layer include core material.

The present invention relates to a patterned fiber substrate comprising: a fiber substrate; and a pattern consisting of a functional material and formed on the fiber substrate, wherein at least a part of the functional material that constitutes the pattern is present in inside of the fiber substrate, the fiber substrate has a contact angle of 100 to 170° with pure water on its surface, and the pattern has a narrowest line width of 1 to 3000 μm.

The disclosure provides a three-dimensional circuit assembly including a printed circuit board comprising a top film surface and a bottom film surface opposite to the top film surface. The three-dimensional circuit assembly may also include a first layer of a composite material bonded or laminated on the top film surface. The three-dimensional circuit assembly may further include a second layer of the composite material bonded or laminated on the bottom film surface of the printed circuit board.

Embodiments disclosed herein include package substrates. In an embodiment, the package substrate comprises a core. In an embodiment, the core comprises a first sub-core layer and a second sub-core layer. In an embodiment, a via is provided through the first sub-core layer and the second sub-core layer. In an embodiment, the via comprises a first hourglass shape in the first sub-core layer and a second hourglass shape in the second sub-core layer. In an embodiment, a front-side buildup layer is over the core and a backside buildup layer is under the core.

A printed circuit board includes an insulating layer, and a first wiring layer at least partially embedded in one surface of the insulating layer, one surface of the first wiring layer being exposed from the one surface of the insulating layer. The insulating layer includes a first insulating layer covering at least a portion of a side surface of the first wiring layer, and a second insulating layer disposed on the first insulating layer and the first wiring layer, and the first and second insulating layers include different insulating materials.

A thermally conductive type polyimide substrate is provided. The substrate comprises at least one insulating layer having a metal layer on a single side or both sides thereof. The material of the insulating layer is a thermally conductive type photosensitive resin having a thermal conductivity of 0.4 to 2, and the thermally conductive type photosensitive resin includes the following components: (a) a photosensitive polyimide, (b) an inorganic filler, and (c) a silica solution. The photosensitive polyimide accounts for 50 to 70% of a total weight of a solid composition of the thermally conductive type photosensitive resin. The inorganic filler accounts for 20-30% of the total weight of the solid composition of the thermally conductive type photosensitive resin, and has a particle size between 40 nm and 5 m. The silica solution comprises silica particles polymerized by a sol-gel process, and the silica particles have a particle size between 10 nm and 15 nm and account for 5 to 30% of the total weight of the solid composition of the thermally conductive type photosensitive resin.

The disclosure provides a three-dimensional circuit assembly including a printed circuit board comprising a top film surface and a bottom film surface opposite to the top film surface. The three-dimensional circuit assembly may also include a first layer of a composite material bonded or laminated on the top film surface. The three-dimensional circuit assembly may further include a second layer of the composite material bonded or laminated on the bottom film surface of the printed circuit board.

Generally, the present disclosure provides example embodiments relating to a printed circuit board (PCB). In an embodiment, a structure includes a PCB including insulating layers with respective metal layers being disposed therebetween. Each of first layers of the insulating layers includes a first fiberglass content. A second layer of the insulating layers has a second fiberglass content less than the first fiberglass content. For example, in some embodiments, the second insulating layer does not include a fiberglass matrix.

A resin composition contains a maleimide compound (A), a cyanate ester compound (B), a polyphenylene ether compound (C) with a number average molecular weight of not lower than 1000 and not higher than 7000 and represented by Formula (1), and a block copolymer (D) having a styrene backbone. In Formula (1), X represents an aryl group; (YO)n.sub.2- represents a polyphenylene ether moiety; R.sub.1, R.sub.2, and R.sub.3 each independently represent a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group; n.sub.2 represents an integer of from 1 to 100; n.sub.1 represents an integer of from 1 to 6; and n.sub.3 represents an integer of from 1 to 4.

##STR00001##

The present invention relates to a patterned fiber substrate comprising: a fiber substrate; and a pattern consisting of a functional material and formed on the fiber substrate, wherein at least a part of the functional material that constitutes the pattern is present in inside of the fiber substrate, the fiber substrate has a contact angle of 100 to 170 with pure water on its surface, and the pattern has a narrowest line width of 1 to 3000 m.