JPH0555414A - Coating method for fine part - Google Patents

Abstract

PURPOSE:To coat bare chip components mounted on a small ceramic substrate with protective resin without any protrusion from the substrate. CONSTITUTION:Spile substrate 3 are alternately provided in the vertical and lateral directions of a small ceramic substrate 2 and a masking agent 8 is printed through a screen mask on the part except for the region where bare chip components 6 are resin-coated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for partially applying a protective coating to bare chip parts mounted on a narrow ceramic substrate used for sensors of measuring instruments.

[0002]

2. Description of the Related Art Conventionally, a ceramic substrate used for a sensor or the like of a measuring instrument is a narrow strip type and printed circuits are provided on both sides, and a chip component is mounted on the substrate or a protective coating is applied. For this reason, handling a small substrate as a single item is disadvantageous both in terms of an automatic machine and in efficiency, so that it is handled as a collective substrate. Also,
Since through holes for connecting the front and back circuits are provided in a narrow board, the through holes are easily broken. Therefore, as shown in FIG.
The aggregate substrate 1 having the through holes 5 formed thereon is formed, the bare chip component 6 is die-bonded and wire-bonded, then the chip component 9 is mounted, the protective resin 7 is coated with an automatic constant-volume dispenser, and the discarded substrate portion 3 is divided. It was sandwiched by a jig and divided to obtain a finished single substrate 2.

[0003]

As described above, when a narrow rectangular ceramic double-sided board is provided with through-holes for connecting the front and back circuits, cracks easily occur. If the board is a collective board, through holes are provided on the dividing lines, chip components are mounted, and protective resin is coated, the boards are narrow,
In addition, it is necessary to lower the viscosity in order to penetrate the resin into the fine parts that are wire-bonded, and as a result the coating resin sticks out of the dividing line and solidifies. Since the coating resin becomes burrs and cannot be stored in a predetermined case, it is necessary to remove burrs.

[0004]

In order to solve the above-mentioned problems, chip components are mounted on a narrow collective substrate on which printed circuits are mounted and chip components are partially coated with resin to divide the chip substrate. Provided is a fine partial coating method, which comprises pre-printing a release-type masking agent that is incompatible with the coating resin except for the portion to be coated with the resin.

[0005]

As described above, in a narrow collective substrate on which the printed circuit is provided and the chip parts are mounted and the resin is partially coated to divide the chip, the chip parts are mounted and the coating is performed except for the resin coating. A masking agent that is not compatible with the resin is printed in advance, then bare chip parts are mounted, wire bonding is performed, resin coating is performed by a discharge machine, and after the coating resin is solidified, the masking agent is peeled off and other chip parts are mounted.

[0006]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a partial plan view of an embodiment showing a fine partial coating method according to the present invention.

In the figure, reference numeral 1 is a collective substrate which is vertically and horizontally arranged, and is a single substrate 2 having printed circuits on both sides.
The discarding substrate portions 3 are alternately provided in the vertical and horizontal directions. A plurality of through holes 5 are provided on the dividing line 4 between the single-piece substrate 2 and the discarded substrate portion 3 to connect the front and back circuits, respectively. A bare chip component 6 is die-bonded and then wire-bonded, and a resin coating 7 is applied for protection. Therefore, except for the resin coating 7 part, a peeling-type masking agent 8 used as a protective treatment agent for parts not to be soldered such as post-applied parts, plated terminals, etc. A screen mask is also printed on the connection land.

After the masking agent 8 is applied by printing with a screen mask on a portion other than the portion where the resin coating 7 is applied to the collective substrate 1 configured as described above, the bare chip parts are die-bonded and wire-bonded, and the resin is discharged by an ejector. After coating and solidification, the masking agent 8 is peeled off, a general chip component is mounted and reflowed, and the discarded substrate portion 3 is held by a dividing jig and divided to complete the single substrate 2.

[0009]

As described above, in a narrow collective substrate on which a printed circuit is mounted and chip parts are mounted, and a resin coating is partially performed for division, a portion where the chip parts are mounted and the resin coating is performed is performed. Except for printing a masking agent that is not compatible with the coating resin beforehand,
Even after the chip parts are mounted and wire bonding is performed, the resin coating can be performed within the range where the masking agent is applied by the effect of the surface tension even if the resin coating is performed by the dispenser. It is remarkable that the substrate having a uniform coating shape can be obtained without the need for burring, which contributes to cost reduction.

[Brief description of drawings]

FIG. 1 is a partial plan view of an embodiment showing a fine partial coating method of the present invention.

FIG. 2 is a plan view of an embodiment showing a conventional fine partial coating method.

[Explanation of symbols]

 1 Assembly board 2 Single board 3 Discarded board part 4 Dividing line 5 Through hole 6 Bare chip part 7 Resin coating 8 Masking agent 9 Chip part

Claims (1)

[Claims] 1. A narrow aggregate substrate on which a printed circuit is mounted, chip components are mounted, and a resin coating is partially performed to divide the chip substrate. A fine partial coating method characterized by pre-printing a peelable masking agent.