JPH04107843U - Structure of wire drawing circuit board - Google Patents

Abstract

(57) [Summary] [Purpose] The present invention aims to reduce the thickness of the line at the starting point of the line drawing due to the resin pool generated at the tip of the line drawing resin dispenser in circuit boards that are potted with a barrier formed by resin drawing. The purpose is to eliminate high [Structure] An opening 34 is provided at the drawing starting point 33 on the circuit board 31, and a resin pool 3 is formed at the tip of the discharger 35.
Absorb 6. [Effect] Line thickness and line height that occur at the starting point of line drawing are eliminated.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to potting circuit boards.

0002

[Conventional technology]

In small devices such as watches, it is not necessary to use already sealed ICs. , bare ICs are often used by being mounted on a circuit board as is. For this reason, IC and It is well known that the IC part is covered with potting resin to protect wires etc. It's technology. Potting methods include insert molding and pre-prepared potting. Method of injecting potting resin after assembling the manufactured barrier to the circuit board , After forming a barrier on the circuit board by resin transfer, potting resin is injected. method, or method of injecting potting resin after forming a barrier by resin wire drawing. and so on.

0003 The barrier used in the above method is applied to areas where there is excess potting resin. The purpose is to prevent it from flowing out and to secure the height to ensure that it covers the IC. It is an essential element in potting work for small equipment. Ru.

0004 The prior art will be briefly explained below with reference to the drawings. About insert molding method There is no need to specifically illustrate the IC part by insert molding with an injection mold. Although it is used for sealing, the injection molds used for each circuit board are expensive.

The barrier assembly method is shown in cross-section in FIG. 1 is a circuit board on which a pattern (not shown) is formed, an IC 2 is mounted at a predetermined position, and a wire 3 connects the IC 2 and the pattern. 4 is a barrier, and a potting resin 5 is injected into this barrier 4 to cover and protect the IC 2 and the wire 3. In the figure, H ₁ indicates the height of the potting portion including the barrier 4, A ₁ indicates the width, and C ₁ indicates the height from the wire 3 to the top of the potting resin 5. However, in such a method, a mold for manufacturing the barrier and a unit for supplying the barrier are required for each barrier, and the positioning and assembly to the circuit board is difficult and requires skill, resulting in poor switchability.

FIG. 3 shows a cross-sectional view of the next transfer barrier method. In FIG. 3, 11 is a circuit board, 12 is an IC, and 13 is a wire, which are almost the same as those in FIG. 2. 14 is a transfer barrier. A potting resin 15 is injected into the transfer barrier 14 to protect the IC 12 and the wire 13. Incidentally, H ₂ indicates the height of the potting portion, A ₂ indicates the width, and C ₂ indicates the height from the wire 13 to the top of the potting resin 15. This method has a low barrier height of 0.1 to 0.2 m/m, making it impossible to pot in narrow areas (flat surfaces).

[0007] Now, in Figures 2 and 3, C₁=C₂Then A₂>A₁It becomes. Pop If the viscosity of the potting resin is increased and potting is performed within a narrow area, the potting area may become It will be expensive (A₁=A₂Then, to protect all 13 wires, H₂>H ₁ turn into. ), making it unsuitable for circuit boards in small devices.

Next, a method of forming a barrier by resin wire drawing will be explained using the cross-sectional view of FIG. 4(a) and the plan view of FIG. 4(b). 21 is a circuit board, 22 is an IC, and 23 is a wire, which has almost the same structure as the above one. Reference numeral 24 indicates a barrier drawn by the ejector 26, and 25 indicates a potting resin reservoir at the tip of the ejector. Note that H ₃ indicates the barrier height, and H ₄ indicates the barrier height formed at the starting point 27. In this method of forming a barrier by drawing a line, if the trajectory is memorized, it can be easily switched with a single button, and the height can also be obtained.

[0009]

[Problem that the idea aims to solve]

In Fig. 4(a), the potting resin pool 25 generated at the dispensing device tip is avoided. This resin pool pours out excess resin at the starting point 27 of the line drawing. Therefore, it appears as line thickness and line height. In particular, the line height is outside the potting height standard. A correction process was required.

0010 The purpose of the present invention is to solve the problem of the line thickness and line height of the line drawing starting point 27, and to achieve a good The goal is to form a barrier.

[0011]

[Means to solve the problem]

The gist of the present invention to achieve the above object is to create a barrier by drawing resin wire. On circuit boards that are potted using a Create a round or irregularly shaped opening with a certain width, and fill the resin with the opening starting from the opening. The feature is that potting is performed after forming the rear.

0012

[Effect]

By using the above method, resin wire is drawn starting from a round or irregularly shaped opening. This eliminates the line thickness and line height at the starting point, making it possible to form a uniform barrier.

[0013]

【Example】

The present invention will be explained below based on the drawings. FIG. 1 shows one embodiment of the present invention, in which (a) is a sectional view and (b) is a plan view. Note that other parts of the IC and barrier are the same as those in FIG. 4, so the same numbers will be used for explanation. 31 is a circuit board, and as shown in FIG. 1, an opening 34 having a round hole shape is formed at a starting point 33 of a barrier 32 formed of wire-drawn resin. The drawing resin pool 36 formed at the dispensing tip of the dispensing device 35 due to the opening 34 enters into the opening 34 as a drawing surplus resin 37 at the resin drawing starting point 33, and the drawing resin pool 36 at the drawing starting point 33 reaches a height H. ₅ is approximately equal to the resin height H ₆ drawn in the direction of arrow 38. After forming the barrier 32 with the wire drawing resin in this way, the IC 22 and the wire 23 can be protected by injecting a potting resin (not shown).

[0014] The viscosity of the wire drawing resin is preferably about 300,000 to 1,000,000 CPS. After drawing if the viscosity is low The resin flows, the lines become thicker, and the height cannot be obtained. Moreover, the tree flowing into the opening 34 As the amount of fat increases, the barrier at the starting point 33 becomes thin and low, causing a phenomenon opposite to that of the conventional method. If the viscosity of one side is too high, the opening at the tip of the dispensing device 35 (not shown) must be enlarged. It is not always possible to obtain thin lines.

[0015] If the opening of the circuit board is round, it is best to make it about 90% of the line width. Explanation below using Figure 5 do. 41 is a circuit board, on which an IC 42 is mounted and connected to the circuit board 4 by a wire 43. 1 pattern (not shown). Now, open the opening 44 of the circuit board 41. When the barrier 45 with a narrow width is formed, the potting resin 46 is applied to the circuit board 41. Excess resin 47 flows through the opening 44 and exposes the IC 42 and the wire 43. The purpose of potting is to protect IC42 and wire 43. It's gone.

[0016] Incidentally, the opening needs to be shaped into an irregular shape (e.g., a long hole) in accordance with the viscosity of the drawing resin. In FIG. 6, a barrier 56 is formed by drawing a line in the direction of an arrow 55 starting from the irregularly shaped opening 54. This represents the case where you are trying to form a In the figure, 51 is a circuit board, 52 is an IC, and 53 represents a wire.

[0017] Also, although not shown, the opening may be a through hole, but the resin in the potting resin reservoir can be It may be a groove that absorbs water.

[0018]

[Effect of the idea]

As described above, according to the present invention, it is possible to form a barrier on a circuit board by drawing a line. If the drawing resin is viscous, a round or irregularly shaped opening should be placed in the circuit board at the starting point of the drawing. Thick lines and lines that occur at the starting point of the line can be removed by simply applying the process of adding lines to the board. high is eliminated.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, (a) is a cross-sectional view;
(b) is a plan view.

FIG. 2 is a cross-sectional view of one embodiment of a conventional barrier assembly method.

FIG. 3 is a cross-sectional view of one embodiment of a conventional transfer barrier method.

4(a) is a cross-sectional view and FIG. 4(b) is a plan view of one embodiment of a conventional wire-drawn barrier system.

FIG. 5 is a cross-sectional view for explaining a problem when the opening is wider than the line width in the present invention.

FIG. 6 is a plan view of an irregularly shaped opening showing one embodiment of the present invention.

[Explanation of symbols]

22 IC 23 wire 31 Circuit board 32 Barrier 33 Starting point of line drawing 34 Opening 35 Dispenser 36 Line drawing resin reservoir 37 Line drawing surplus resin 38 Line drawing direction A Potting width C Minimum wire coating thickness H Potting height

Claims (1)

[Scope of utility model registration request] Claim 1: In a circuit board that is potted with a barrier formed by drawing a resin wire, a circular or irregularly shaped opening having a width smaller than the width of the drawn portion is formed in the drawn portion, and the barrier is formed using the resin starting from the opening. A structure of a circuit board for wire drawing characterized by potting the part formed with the .