JPH0113427Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a mounting structure for electronic components such as LSI.

[Prior art]

Electronic components such as LSIs and transistors are placed on the electrode pattern on the substrate, the electrode surface is electrically connected to the electrode pattern, and resin sealing is applied to securely hold the electronic component on the substrate. A mounting structure for electronic components is known. In such a configuration, there is a problem that the board becomes thick because electronic components are mounted on the board. This is particularly problematic in the case of modular configurations such as thin electronic wristwatches, where it is desirable to make them as thin as possible.

Therefore, as shown in FIG. 1, a counterbore 2 is formed on the top surface of the substrate 1, and an electronic component 3 such as an LSI is placed in the counterbore 2, and then the electronic component 3 is connected with a wire 4. 3 and the electrode pattern 5 on the top surface of the substrate 1, and in this state, resin 6 is poured into the counterbore 2 to seal the electronic component 3, and then an insulating thin film 7 is covered on the front and back surfaces of the substrate 1. Something is being devised.

Further, as shown in FIG. 2, after forming a through hole 9 in the circuit board 8, a metal plate 10 is fixed to the lower surface of the circuit board 8 to close the through hole 9, and an electronic component is inserted into the through hole 9. 11 and connect the electronic component 11 and the electrode pattern 13 of the substrate 8 with the wire 12. In this state, the resin 14 is placed in the through hole 9.
Another method has been devised in which the electronic components 11 are sealed by pouring the insulating film into the substrate 8, and then the front and back surfaces of the substrate 8 are covered with an insulating thin film 15.

[Problems with conventional technology]

However, in the above-mentioned mounting structure for electronic components, in the former case, the counterbore process to form on the circuit board is troublesome, and in the latter case, the metal plate is stuck under the through hole formed in the circuit board. The disadvantage is that the processing is troublesome and the number of parts increases. Moreover, in the former case, the thickness of the electronic component mounting portion left by the counterbore (the thickness a of the circuit board) directly affects the thickness of the entire circuit board, so it is not suitable for thin shapes. In the latter case, the thickness b of the metal plate directly affects the thickness of the entire circuit board, and therefore, like the former, it is not suitable for thinning.

[Purpose of invention]

The present invention was developed in consideration of the above-mentioned circumstances, and aims to provide a mounting structure for electronic components that can reduce the overall thickness of the circuit board and can be easily processed. It is.

[Key points of the idea]

In order to achieve the above object, the present invention extends a photosensitive film resist attached to the bottom surface of a circuit board so as to cover a through hole formed in the circuit board, and also extends the photosensitive film resist attached to the bottom surface of the circuit board to cover a through hole formed in the circuit board. An electronic component is placed in the through hole.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4. In the figure, reference numeral 16 is a circuit board, and this circuit board 16 is the fourth
A through hole 17 is formed in the punching process as shown in FIG.
As shown, electrode patterns 18, 1 are provided on both the upper and lower surfaces.
9 and as shown in FIG. 4c, the circuit board 1
Photosensitive film resists 20 and 21 are deposited on the electrode patterns 18 and 19 on both the upper and lower surfaces of the circuit board 16, that is, on the upper and lower surfaces of the circuit board 16. Then, as shown in FIG. 4d, with the mask members 22 and 23 applied to the required locations of each photosensitive film resist 20 and 21, ultraviolet rays are applied to the photosensitive film resist 2.
0 and 21 are cured, and then the uncured portions, that is, the portions to which the mask members 22 and 23 were applied are removed to expose the electrode patterns 18 and 19. Then, plating 24 is attached to the exposed lower electrode pattern 19 to complete the substrate structure as shown in FIG. 4e. In the substrate structure constructed in this manner, an electronic component 25 such as an LSI is inserted into the through hole 17 and placed on the photosensitive film resist 21 on the lower surface of the substrate 16. This situation is shown in FIG. 4f. Thereafter, on the upper surface of the substrate 16, as shown in FIG.
8 and the through hole 17.
The electronic component 25 is held and fixed to the board 16 by the solder 26 that has entered the gap between the electronic component 25 and the electronic component 25.

In the figure, reference numeral 27 is a coil spring that comes into elastic contact with the plating 24, and this coil spring 27 is electrically connected to a sound reporting device (piezoelectric element), not shown.

In such a configuration, the photosensitive film resist 21 on which the electronic components 25 are placed has a thickness of approximately 50 μm, and the thickness of the entire substrate structure is smaller than that in a case where a metal plate is fixed to the bottom surface of the substrate 16 and electronic components are placed on this. can be minimized. Moreover, the photosensitive film resist 21 is originally provided on the substrate 16, and does not require any special parts such as a metal plate on which the electronic parts 25 are mounted, nor does it require processing such as adhesion. be. Further, since the through hole is formed without counterboring, it is easy to process and can be formed at the same time as the punching of the substrate 16, which has the advantage of simplifying the process.

[Effect of idea]

As detailed above, the present invention includes a circuit board having a through hole formed from the upper surface to the lower surface, and a photosensitive film resist attached to the lower surface of the circuit board so as to cover the lower surface of the through hole. Since the electronic component is arranged in the through hole and mounted on the upper surface of the photosensitive film resist, it is easy to process and the number of parts can be reduced, and the overall thickness of the circuit board can be reduced. This has the practical advantage of allowing more compact assembly.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional side views of the conventional product, 3 are longitudinal sectional side views showing an embodiment of the present invention, and 4
Figures a to g are longitudinal sectional side views showing the mounting structure of the present invention according to the processing procedure. 16... Circuit board, 17... Through hole, 18,1
9... Electrode pattern, 20, 21... Photosensitive film resist, 22, 23... Mask member, 24
...Metsuki, 25...Electronic parts, 26...Solder,
27...Coil spring.

Claims (1)

[Scope of utility model registration request] A circuit board in which a through hole is formed, an electrode pattern provided near one opening of the through hole of this circuit board, and an electrode pattern that is attached to cover the other opening of the through hole of the circuit board. It consists of a photosensitive film resist, an electronic component placed in the through hole of the circuit board and mounted on the photosensitive film resist, and a solder layer that electrically connects the electronic component and the electrode pattern. and an electronic component mounting structure in which an electronic component mounted on the photosensitive film resist is held and fixed within the through hole by the solder layer.