Board module and method of manufacturing same
A liquid crystal display device ( 100 ) includes a glass substrate ( 110 ) having an LSI chip ( 130 ) and an FPC board ( 140 ) mounted thereon. A component ACF ( 150 a ) made of a single sheet is used to further mount discrete electronic components such as stabilizing capacitors ( 150 ) on the glass substrate ( 110 ). The component ACF ( 150 a ) has a size that covers not only a region where the discrete electronic components are to be mounted, but also the top surfaces of the LSI chip ( 130 ) and the FPC board ( 140 ) which are mounted first. By thus using the large component ACF ( 150 a ), a positional constraint upon adhering the component ACF ( 150 a ) to the glass substrate ( 110 ) is eliminated, reducing the area of a region where the discrete electronic components are mounted. By this, a board module miniaturized by reducing the area of a region where discrete electronic components are mounted is provided.
1. A board module having a plurality of electronic components mounted on a substrate by anisotropic conductive adhesives, the board module comprising:
a plurality of regions arranged on a surface of the substrate including a first, a second, and a third region;
anisotropic conductive adhesives including first, second, and third anisotropic conductive adhesives having different characteristics from one another;
the plurality of electronic components including a first electronic component mounted on the first region by the first anisotropic conductive adhesive, a second electronic component mounted on the second region by the second anisotropic conductive adhesive, and a third electronic component mounted on the third region by the third anisotropic conductive adhesive; wherein
the third anisotropic conductive adhesive is integrally provided by a single monolithic body and is provided on at least a surface of the first electronic component, on a top surface of the second electronic component, and on the third region.
2. The board module according to claim 1 , wherein
the third anisotropic conductive adhesive covers at least a top surface of the first electronic component, the second region, and the third region, and
the second electronic component and the third electronic component are mounted in the second region and the third region, respectively, by the third anisotropic conductive adhesive.
3. The board module according to claim 2 , further comprising a second anisotropic conductive adhesive adhered to the second electronic component, wherein
the second electronic component is mounted in the second region by the second anisotropic conductive adhesive and the third anisotropic conductive adhesive.
4. The board module according to claim 1 , wherein
a Young's modulus of the first electronic component is higher than a Young's modulus of the second electronic component,
a storage elastic modulus of the first anisotropic conductive adhesive is higher than or equal to a storage elastic modulus of the second anisotropic conductive adhesive, and
tack strength of the first anisotropic conductive adhesive is lower than tack strength of the second anisotropic conductive adhesive.
5. The board module according to claim 4 , wherein
the substrate is a rigid substrate, and
the storage elastic modulus of the first anisotropic conductive adhesive is 1.5 to 2.0 GPa, and the storage elastic modulus of the second anisotropic conductive adhesive is 1.2 to 1.3 GPa.
6. The board module according to claim 4 , wherein a size of conductive particles respectively contained in the first, second, and third anisotropic conductive adhesives increases in order of the first, second, and third anisotropic conductive adhesives, and a pitch of terminals respectively provided on the first, second, and third electronic components increases in order of the first, second, and third electronic components.
7. The board module according to claim 1 , wherein
a Young's modulus of the first electronic component is higher than a Young's modulus of the third electronic component,
a storage elastic modulus of the first anisotropic conductive adhesive is higher than or equal to a storage elastic modulus of the third anisotropic conductive adhesive, and
tack strength of the third anisotropic conductive adhesive is higher than tack strength of the first anisotropic conductive adhesive.
8. The board module according to claim 7 , wherein conductive particles contained in the third anisotropic conductive adhesive are larger than conductive particles contained in the first anisotropic conductive adhesive, and a pitch of terminals provided on the third electronic component is larger than a pitch of terminals provided on the first electronic component.
9. The board module according to claim 1 , wherein the third anisotropic conductive adhesive has an opening at least in a portion thereof corresponding to a top surface of the first electronic component.
10. The board module according to claim 1 , wherein
the substrate is a rigid substrate having a trace formed on a surface thereof,
the first electronic component is a semiconductor chip having a bump electrode formed on a surface of a semiconductor substrate, and
the semiconductor chip is mounted by connecting the bump electrode to the trace on the rigid substrate.
11. The board module according to claim 1 , wherein
the substrate is a flexible substrate having a trace formed on a surface thereof,
the first electronic component is a semiconductor chip having a bump electrode formed on a surface of a semiconductor substrate, and
the semiconductor chip is mounted by connecting the bump electrode to the trace on the flexible substrate.
12. The board module according to claim 1 , wherein
the first electronic component is a semiconductor element formed on a semiconductor substrate,
the second electronic component is a flexible printed circuit board, and
the third electronic component is a discrete electronic component.
13. A display device comprising the board module according to claim 12 , wherein
the board module further includes a display portion formed on the substrate, and
the semiconductor element is a drive element that drives the display portion based on a signal provided from an external source through the flexible printed circuit board.