JP2937775B2 - Mounting structure of ribbon coil on printed circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a mounting structure for mounting a thin coil formed by winding a conductive thin film such as a copper foil provided with an insulating layer on a printed circuit board.

[0002]

2. Description of the Related Art Conventionally, as a motor coil for a flat type capstan motor or the like, a conductive thin film such as a copper foil provided with an insulating layer is wound in place of a general wire coil to improve a coil conductor space factor. A thin strip coil obtained by slicing a turned rod-shaped wound body into slices is often used.

[0003] As a mounting structure for mounting the ribbon coil having the above configuration on a printed circuit board, a mounting structure shown in FIG. 2 (for example, see Japanese Utility Model Publication No. 2-27523) is known. In the figure, 1 is a printed circuit board, 1a is a wiring pattern, 2 is a thin coil, 2a is an insulating layer provided on the coil surface, 3 is solder, 4 is a heat-resistant insulating layer provided on the coil-facing surface side of the coil. The heat-resistant insulating layer 4 is made of, for example, an ultraviolet-curable or thermosetting epoxy resin having a heat-resistant temperature higher than the melting temperature of the solder.

[0004]

According to the coil mounting structure having the above-mentioned structure, the heat-resistant insulating layer 4 is provided there even if it flows between the bottom of the solder coil and the substrate during solder mounting. There is an advantage that the insulating layer 2a is not melted, so that a short circuit between coil layers can be prevented from occurring. However, in the coil mounting structure having the above-described structure, since the insulating layer 2a is formed on the coil, the heat-resistant insulating layer is formed again, and a thermosetting resin is used, there is a problem that the mass productivity is very low. There is a point.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a structure for attaching a thin coil to a printed circuit board which can prevent a short circuit between coil layers without separately providing the heat-resistant insulating layer. The main purpose is to

[0006]

In order to achieve the above object, the present invention provides a method for coating at least one end surface of a ribbon coil with a thermoplastic resin having a heat-resistant temperature lower than a melting temperature of solder and a side coated with the resin. It is characterized in that it is placed in contact with a printed circuit board, and the pattern of the printed circuit board and the innermost and outer peripheral surfaces of the coil are connected by soldering. Examples of the thermoplastic resin include a polyamide resin, a polyethylene terephthalate resin, an ester imide resin, a polybutylene terephthalate resin, a fluorine resin, and a vinyl chloride resin.

[0007]

In the coil mounting structure having the above-mentioned structure, since the thermoplastic resin having a lower melting point than the solder melting temperature is coated on the end face of the coil on the printed circuit board, the resin melts out at the time of soldering, and the resin melts. And solder can be formed in a bridge shape.

[0008]

FIG. 1 shows an embodiment of the present invention. FIG.
1A shows a state before solder mounting, and FIG. 1B shows a state after solder mounting. 1A and 1B, reference numeral 10 denotes a printed circuit board; 10a, a wiring pattern;
Reference numeral 1 denotes a thin coil. A thermoplastic resin layer 11a having a heat-resistant temperature lower than the solder melting temperature is formed at an end of the coil 11. The thermoplastic resin includes an ester imide resin,
Using a polyamide resin, a fluororesin (300 cps or less), and a vinyl chloride resin, coating the end face of the coil with a roll, and then heating and drying (120 ° C. to 200 ° C.)
(C for 15-60 seconds).

Therefore, as shown in FIG. 1A, a thin coil 11 is arranged on a printed circuit board 10, and a cream solder 12 is supplied from a nozzle (not shown) to the coil connection surface to be applied. Then, as shown in FIG. 1 (B),
When the cream solder 12 is melted by the reflow process, the resin on the substrate end surface side of the coil slightly melts due to the heat of the melting, and a resin dam portion 11b is formed between the resin and the pattern 10a. The solder was formed in a bridge shape, and a clean solder bridge connection was obtained.

[0010]

As described in detail below, according to the present invention,
The following effects can be obtained. (1) Since a thermoplastic resin having a heat-resistant temperature lower than the solder melting temperature is provided on the mounting end face side of the ribbon coil, a part of the resin melts out at the time of solder mounting to form a resin weir. A short circuit between the coil layers due to the flow can be prevented. Therefore, according to this coil mounting structure, mass productivity is improved. (2) Since it is only necessary to coat the liquid thermoplastic resin on the end surface of the ribbon coil (at least on the mounting end surface side), an insulating film can be formed in a simple process at low cost. (3) Especially when mounted on a CD pickup or the like, cracking or cracking of the insulating film due to bending of the coil has been a serious problem (short circuit has occurred due to invasion of foreign matter, water, etc.). In this case, since the thermoplastic resin is softened again by the heat at the time of solder connection, there is an advantage that cracks and cracks are sealed.

[Brief description of the drawings]

1A is a cross-sectional view of a thin coil mounting structure before mounting, and FIG. 1B is a cross-sectional view of the thin coil mounting structure after mounting.

FIG. 2 is a cross-sectional view of a conventional structure for attaching a thin coil to a printed circuit board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Printed board 10a Wiring pattern 11 Thin coil 11a Thermoplastic resin layer 12 Solder

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01F 5 / 00,5 / 04 H01F 17 / 00,41 / 04 H02K 3/26 H05K 1/18

Claims (1)

(57) [Claims] At least one of end faces of a ribbon coil is coated with a thermoplastic resin having a heat-resistant temperature lower than a melting temperature of solder, and the resin-coated side is placed in contact with a printed circuit board. A structure for attaching a thin coil to a printed circuit board, wherein a pattern and innermost and outermost surfaces of the coil are connected by soldering.