JP3490372B2 - Printed circuit board and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step of solder resist printing when a conductive paste jumper wire is formed on a printed board by a printing method.

[0002]

2. Description of the Related Art In a printed circuit board manufacturing process, heat curing is performed to increase the insulation property such as securing a distance between a copper foil signal circuit pattern on the circuit board and a conductive paste to pass over it, and pinhole blocking during printing. The steps of printing and curing the mold-type solder resist ink (at 140 to 150 ° C. for 20 to 30 minutes) are repeated three times.

Further, after the printing and curing of the solder resist is completed, the process of printing and curing the symbol mark, and further printing and curing of the conductive paste requires heat of 140 to 150 ° C. five times in all steps. This will be the case.

As a result, the base material becomes hard and brittle, and cracks occur between the holes in the mold and between the holes with a narrow pitch when punching the outer shape. Further, the substrate warps due to heat. When it is large, a warp of about 15 mm (usually a few mm) occurs, and in the printing process, the vacuum of the printing table makes it impossible to fix the board, and the flatness and position accuracy cannot be maintained, and printing is performed at the corners of the board. The plate is damaged and the substrate is displaced when the printing table is moved, causing problems.

Further, in a post-process die-cutting process using a die, a continuity inspection device, and a copper foil surface treatment device, a substrate with large warpage is caught on a roller conveyor.

[0006]

DISCLOSURE OF THE INVENTION The present invention can reduce the steps (heat history) to which high heat is applied, can suppress the deterioration of the base material and the warp of the substrate, and there is no warp of the substrate. (EN) Provided are a printed circuit board and a method for manufacturing the same, which can prevent malfunction of contacts (contact of switch contacts is kept incomplete, contact failure of switch contacts, etc.).

[0007]

According to the present invention, when a conductive paste is used as a jumper wire by a screen printing method on a single-sided printed circuit board, a solder resist which is an insulator between the copper foil pattern and the conductive paste is formed. The method is characterized in that the method is applied overlaid with a special solder resist ink to increase the insulation between the copper foil signal circuit pattern on the substrate and the conductive paste.

The present invention specifically provides the following apparatus and method.

According to the present invention, in a printed circuit board in which a copper foil signal circuit pattern and a conductive paste layer are insulated with an insulator to form a conductive jumper, a solder resist forming the insulator is temporarily hardened by ultraviolet rays. Type solder ink is used for solder resist printing and temporary curing,
Overcoat with a thermosetting solder resist ink that is temporarily hardened with the same ultraviolet light, temporarily harden it, and then heat harden it to form an undercoat, and print a conductive paste on the upper side to heat harden it. , When measuring the warp of the substrate under the following conditions, that is, when the substrate (length L) is placed horizontally on a surface plate at room temperature and the amount of warpage (lifting H) that is the rise of the substrate is measured with a gap gauge. Provided is a printed circuit board in which the warpage (warpage per unit length) of the board is warped (%) = ( H / L ) × 100 = 0.5 to 0.3%.

The present invention relates to a method of manufacturing a printed circuit board in which a copper foil signal circuit pattern and a conductive paste layer are insulated with an insulator to form a conductive jumper. Solder-resist printing is performed using a curable solder ink to temporarily cure, and the undercoat 1 and undercoat 2 are over-coated with thermosetting solder ink that is temporarily cured on the upper side of the solder resist print with the same ultraviolet light to temporarily cure. And then heat-curing, printing a conductive paste on the upper side of these to make them conductive with the copper foil signal circuit pattern and heat-curing,
Using thermosetting solder ink that is temporarily hardened by ultraviolet rays,
Provided is a method for manufacturing a printed circuit board, which gives a thermal curing history only twice.

According to the present invention, in a method for manufacturing a printed circuit board in which a copper foil signal circuit pattern and a conductive paste layer are insulated with an insulator to form a conductive jumper, heat for temporarily curing the copper foil signal circuit pattern with ultraviolet rays is used. Undercoat with a thermosetting solder resist ink that performs solder resist printing using a curable solder ink, temporarily hardens it with ultraviolet light up to about 80 ° C at the plate surface temperature, and temporarily hardens with the same ultraviolet light on the upper side of the solder resist printing. 1 and undercoat 2 are respectively printed and temporarily cured by ultraviolet rays, and solder resist, undercoats 1 and 2 are heated to about 140 ° C. to perform main curing, and then conductive paste printing is performed on these upper sides. It has a step of curing by heating above the above temperature and uses a thermosetting solder ink that is temporarily cured by ultraviolet rays. To provide a method of manufacturing a printed circuit board to provide only a thermosetting history twice.

After the formation of the undercoat 2, a symbol mark can be printed using an ultraviolet curable ink to cure the symbol mark with ultraviolet light.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a printed circuit board constructed according to the present invention. In the figure, a conductive paste jumper portion 2, a signal pattern 3, a manufacturing soldering land 4 and a carbon switch contact 5 are provided on a substrate 1. The symbol mark 21 and the like are formed.

2 and 3 show the details of the conductive paste jumper portion 2 in a plan view and a cross section, respectively. In these figures, the conductive paste jumper portion 2 has a conductive paste layer 8 for conducting the copper foil land (A) 6 having the copper foil signal circuit pattern 11 and the copper foil land (A ′) 7. Therefore, the copper foil lands 6 and the copper foil lands 7 have conductive paste grounding points 9 and 10, respectively, and are connected to the conductive paste layer via these points. A circuit pattern 23 to the ground point is connected to the copper foil land (A ') 7.

The copper foil signal circuit pattern 11 is drawn out from the conductive paste jumper portion 2 as the signal circuit pattern 12, and itself forms a signal circuit.

Conductive Paste Grounding Point In order to obtain conduction between the copper foil lands 6 and 7, printing is performed with a screen plate using a conductive paste, and the paste is cured and connected to ensure electrical conduction. At that time, since insulation from the signal circuit pattern 12 is required, three insulating layers are formed by a printing method as shown in FIG.

On the copper foil signal circuit pattern 11 and the substrate 1
The solder resist layer 13 is provided on the upper side, the undercoat 1 layer 14 and the undercoat 2 layer 15 are formed on the upper side thereof, and the conductive paste layer 8 is formed on the undercoat 1 layer 14 and the undercoat 2 layer 15 to form the conductive paste jumper portion 2 described above. .

The solder resist layer 13, the undercoat 1 layer 14, and the undercoat 2 layer 15 constitute an insulator for insulating the copper foil signal circuit pattern 11 and the conductive paste layer 8.

The solder resist layer 13, the undercoat 1 layer 14 and the undercoat 2 layer 15 are formed by using a thermosetting resist ink which is temporarily cured by ultraviolet rays as described later. As an example of the composition of this resin, the one shown in Table 1 is used.

[0021]

[Table 1]

FIG. 4 shows a manufacturing process.

The copper foil-clad laminate 21 is cut with a copper foil (a). Copper foil signal circuit pattern 11 forming a signal circuit by etching, conductive paste ground points 9, 10,
The component soldering land 4 is formed. The component soldering land 4 serves as a component mounting copper foil land (b).
A thermosetting solder resist ink (hereinafter, UV temporary curing + heat) that is temporarily cured by ultraviolet rays (light) on the plate surface on the copper foil signal circuit pattern 11 and is temporarily cured due to heat of about 80 ° C. A curable solder resist ink is used) to perform solder resist printing to form a solder resist (layer) 13 (c). UV light is applied to perform temporary curing. Next, undercoat 1 printing is performed using the same material, UV temporary curing + thermosetting solder resist ink (d). UV light is applied to perform temporary curing. Undercoat 2 printing is carried out by applying multiple layers of UV temporary curing + thermosetting type solder resist ink (e). Temporary curing is performed by UV irradiation. Then, the main curing is performed by heating. Next, conductive paste printing is performed (d). Main curing is performed by heating.

The following is a summary of these steps.

Pattern lands are formed by etching the copper clad laminate of the material.

A portion of the copper foil signal circuit pattern other than the copper foil lands for soldering components and the conductive paste ground copper foil lands is printed with a UV-temporary-curing + thermosetting-type solder resist ink using a screen plate, and immediately after that. The ink is cured to prevent solder adhesion to unnecessary parts during component mounting, insulation protection between copper foil signal circuit patterns that are signal circuits, and protection of the printed wiring board from the external environment for a long time.

In order to secure insulation (distance, etc.) between the copper foil signal circuit pattern which is the signal circuit as the undercoat 1 and the conductive paste to be printed later, after printing the above-mentioned solder resist, the above-mentioned solder is used. The same ink as the resist is printed and cured again.

Further, in order to secure insulation (distance, etc.) as the undercoat 2, printing and curing are performed with the solder resist ink described above and before.

After that, by printing and curing the conductive paste with a screen plate, the arbitrarily placed conductive paste ground point copper foil lands can be connected to each other and electrical conduction can be obtained.

FIG. 5 shows a flow chart which is an embodiment of the present invention. For reference, a conventional flowchart is shown in FIG.

In FIG. 5, the material is cut (S1), and a copper foil pattern land is formed by etching (S).
2). Perform solder resist printing by screen printing using UV temporary curing + thermosetting resist ink (S
3).

UV (ultraviolet) curing furnace is used to perform UV temporary curing, that is, solder resist curing (S4).

Temporary curing is carried out by raising the plate surface temperature to about 80 ° C. by ultraviolet rays, and the time is about 1
It is about 0 seconds.

Undercoat 1 printing is carried out using an ultraviolet temporary curing + thermosetting solder resist ink having the same quality as the ultraviolet temporary curing + thermosetting solder resist ink.
(S5). UV temporary curing, that is, undercoat 1 curing is performed using a UV curing furnace (S6). Similarly, undercoat 2 printing (S7) and undercoat 2 curing are performed (S
8). Symbol mark printing is performed using the symbol mark ink or UV curable ink (S9). The symbol mark is a character or symbol on the substrate 1 and is printed by a white symbol mark. Since the UV curable ink is used, the substrate is not exposed to high temperature in forming the symbol mark. UV curing, that is, UV curing, that is, symbol mark curing is performed using a UV curing furnace (S10). Using a heat curing furnace,
The temperature of the undercoats 1 and 2 is raised to 140 ° C. and maintained for 20 minutes to perform main curing, that is, solder resist main curing (S11). Conductive paste printing is performed using conductive paste or thermosetting ink (S1
2). The temperature is raised to 160 ° C. in a heat curing furnace and held for 30 minutes to cure the conductive paste (S13).

As shown in FIG. 6, in the conventional method, the 140 ° C. heating step is performed four times, the 160 ° C. heating is performed once, and the high heat history is performed five times in total. It is a method in which a high heat history is given only once in the process and once at 160 ° C. for a total of two times.

By using the UV-temporary curing + thermosetting type solder resist ink, the process of applying high heat is performed only 5 to 2 times, so that the deterioration of the base material and the warp of the substrate can be suppressed. be able to.

When the warpage of the substrate was measured under the following conditions,
That is, as shown in FIG. 9, the substrate 1 is placed on the surface plate 22 at room temperature.
When the board 1 is placed horizontally and the floating degree of the board 1 is measured with a gap gauge, and the board warpage (warpage per unit length) is when the board length is L and the warp amount is H, The amount (%) = (H / L) × 100 = 0.5 to 0.3% can be set.

FIG. 7 shows the heat history in a table, and FIG. 8 shows the heat history in a graph.

As shown in FIG. 8, 1
It is 40 ° C. or more high history and consists step given et been Ru only twice, the time required for manufacturing, is halved compared to the process both conventional. By eliminating the warp of the board,
Yield is improved because malfunction of carbon switch contacts can be eliminated.

[0040]

EFFECTS OF THE INVENTION By using a UV-temporary-curing + thermosetting type solder resist ink, it is possible to suppress the deterioration of the base material and the warp of the substrate by performing the process (heat history) requiring high heat in 5 to 2 times. .

Further, since there is no warp of the substrate, it is possible to prevent erroneous operation of the carbon switch contact (the switch contact is kept in contact, the switch contact is not properly contacted, etc.).

[Brief description of drawings]

FIG. 1 is an external view of a printed circuit board to which the present invention is applied.

FIG. 2 is a plan view of a conductive paste jumper portion.

FIG. 3 is a sectional view of FIG.

FIG. 4 is a manufacturing process diagram.

FIG. 5 is a flow chart diagram.

FIG. 6 is a flowchart of a conventional product.

FIG. 7 is a diagram illustrating a process.

FIG. 8 is a thermal history graph diagram.

FIG. 9 is a diagram showing a measurement example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Board, 2 ... Conductive paste jumper part, 3 ... Signal pattern, 4 ... Manufacturing soldering land, 5 ... Carbon switch contact, 6 ... Copper foil land (A), 7 ... Copper foil land (A '), 8 ... Conductive paste layer, 9, 10 ... Conductive paste ground point, 11 ... Copper foil signal circuit pattern, 12 ... Signal circuit pattern, 13 ... Solder resist (layer), 14 ... Undercoat 1 (layer), 15 ... Undercoat 2
(Layer), 21 ... Symbol mark.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H05K 3/00 H05K 3/28 H05K 3/40

Claims (4)

(57) [Claims] 1. In a printed circuit board having a conductive jumper formed by insulating a copper foil signal circuit pattern and a conductive paste layer with an insulator, a thermosetting solder for temporarily curing a solder resist forming the insulator with ultraviolet rays. ink temporarily cured by performing a solder resist printing was used to recoated with thermosetting solder resist ink is temporarily cured in the same ultraviolet, temporary curing of
Then, heat cure to form an undercoat, print a conductive paste on the upper side of the undercoat, and heat-cures the main paste, and measure the warp of the substrate under the following conditions: When the length (L) is placed horizontally and the amount of warpage (floating H), which is the rise of the substrate, is measured with a gap gauge, the warp of the substrate (warpage per unit length) is the amount of warpage (%) = ( H / L ) × 100 = 0.5-0.3% The printed circuit board characterized by the above. 2. A method of manufacturing a printed circuit board, wherein a copper foil signal circuit pattern and a conductive paste layer are insulated with an insulator to form a conductive jumper. Solder ink is used to perform solder resist printing, which is temporarily cured with UV light, and thermosetting solder ink that is temporarily cured with the same UV light on the upper side of the solder resist print. Temporary curing, then heat curing, and a step of printing a conductive paste on the upper side of these to make them conductive with the copper foil pattern and heat curing, using a thermosetting solder ink that is temporarily cured by ultraviolet rays,
A method of manufacturing a printed circuit board, wherein the heat curing history is given only twice. 3. A method of manufacturing a printed circuit board, wherein a copper foil signal circuit pattern and a conductive paste layer are insulated by an insulator to form a conductive jumper, wherein a thermosetting type in which the copper foil signal circuit pattern is temporarily hardened by ultraviolet rays. Solder-resist printing is performed using solder ink, and the board surface temperature is temporarily hardened by ultraviolet rays up to about 80 ° C., and the upper side of the solder resist printing is temporarily hardened by the same ultraviolet rays. The undercoat 2 is printed and temporarily cured by ultraviolet rays, and the solder resist, undercoats 1 and 2 are heated to about 140 ° C.
Performed to curing heat up, then, by performing conductivity-type paste printing to these upper with rows cormorants steps cured by heating to above the temperature, using the heat-curable solder ink temporarily cured by ultraviolet ,
A method of manufacturing a printed circuit board, wherein the heat curing history is given only twice. 4. The manufacturing of a printed circuit board according to claim 2, wherein after the undercoat 2 is formed, the symbol mark is printed by using an ultraviolet curable ink to cure the symbol mark with ultraviolet light. Method.