JPS62291088A - Manufacture of circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a method of manufacturing a circuit board, which is an improved method of forming metal wiring on a circuit board.

[Technical background of the invention and its problems]

A circuit board is a substrate made of an insulating material on which metal wiring is formed, and this metal wiring is composed of electrodes that connect to terminal electrodes of electronic components, and leads that connect these electrodes.

The circuit board has a structure in which the electrodes are formed independently in a convex shape by forming a thinner part between the electrode and the lead in the metal wiring compared to the thickness of these parts. It has been adopted.

When manufacturing circuit boards, metal wiring is formed by photo-etching, so when forming metal wiring that has a thick wiring part and a thin wiring part, the thin wiring part is half-etched. A method of forming a hole is adopted.

Thus, a configuration in which metal wiring is provided from a thick wiring portion and a thin wiring portion in a circuit board is used, for example, in a circuit board on which a semiconductor chip is mounted.

FIG. 3 shows an example of this circuit board, in which a semiconductor chip 7''21 is provided with electrode pads 22, 22 made of aluminum or the like on both sides of its lower surface, and electrode pads 22, 22 are provided on the lower surface.
An overcoat layer 23 such as the above is formed. The circuit board has electrodes 2 on the surface of a substrate 1 made of an insulating film such as polyester or polyimide at intervals so as to face electrode pads 22 of the semiconductor chip 2.
, 2, and each of these electrodes 2, 2tlC thin wiring portion 4
, 4, with leads 3, 3 formed therebetween. The metal wiring consists of electrodes 2, 2 and leads 3, 3, which are thick wiring parts.
and thin wiring portions 4, 4, which are made of conductive metal such as copper or aluminum. Thin wall m part 4,
4 is formed by half etching, and due to the presence of the thin wiring portions 4, the stain poles 2, 2 are formed in a convex shape independently of the leads 3, 3. Note that the semiconductor chip 2 is placed above the electrodes 2, 2 of the circuit board, and is bonded to the electrodes 2, 2 via an anisotropic conductive adhesive 24.

Next, a method for forming the circuit board will be described by taking as an example the case of a circuit board shown in FIG. 3, which is made of a metal circuit board consisting of a thick wiring part and a thin wiring part. In this example, a positive photorenost is used. First, a metal layer 5 is formed on the substrate 1,
Further, a layer of photoresistance is applied over the metal layer 5 (FIG. 4 (elephant)).

Next, a photomask or the like is prepared, and the photoresist 6 is exposed to ultraviolet light (FIG. 4(b)).

F.) -r x p'J'h, it has a mask 8 with a middle turn that shields the entire metal wiring of the circuit board from light, and irradiates light onto the portion of the photoresist 6 other than the metal wiring portion. After exposure, photolithography and etching are sequentially performed to remove the portions irradiated with the photorenostro light and the corresponding portions of the metal layer 5, respectively.
d)), and further remove the remaining portion of the photoresist 6 to leave a portion of the metal layer 5 corresponding to the metal wiring (Fig.
・)). Next, a layer of photoresist 9 is deposited on the surface of the remaining metal layer 5 and the exposed surface of the substrate 1 (see Fig. 4)), and then fog light is applied using a photomask 10 (see Fig. 4). g)). The mask 11 of the photomask 10 is
Electrodes 2, 2 and leads 3, 3 in metal wiring of a circuit board
It has nine turns that shield only each portion of the etching, and the portions corresponding to the thin wiring portions 4, which require half-etching, are open. As a result, light is irradiated to the portions of the photorenostro that correspond to the thin wiring portions 4, 4 and the substrate 1. Next, the exposed portion of the photoresist No. 0 exposed to light is removed by performing a cleaning process to expose the metal layer 5 (the fourth
(h)), this exposed portion of the metal layer 5 is subjected to half-etching, and finally, the remaining portion of the photoresistance layer is peeled off to form the electrodes 2, 217.
- Poi ΔCj)) forming a metal wiring consisting of the nodes 3, 3 and the thin wiring portions 4, 4.

However, in the conventional method for forming metal wiring in the manufacture of circuit boards, exposure and etching are required when forming the outer shape of the metal wiring and when forming each part including the thin wiring part, that is, the half-etched part of the metal wiring. In order to carry out the etching process, two exposure and etching steps are required, and there is a problem in that the number of steps is large and time-consuming.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to provide a method for manufacturing a circuit board that can easily manufacture a circuit board provided with metal wiring having a thin wiring portion.

[Summary of the invention]

The method for manufacturing a circuit board of the present invention is a method for manufacturing a circuit board in which metal wiring consisting of a thick wiring portion and a thin wiring portion is formed on a substrate, and the metal wiring is connected to a metal layer formed on the substrate. When performing the patterning, use a photomask having an A' turn in which the part of the metal wiring corresponding to the thick wiring part is completely light-shielding or completely light-transmitting, and the part corresponding to the thin wiring part is partially light-shielding. It is characterized by: That is, by performing exposure using a mask having the above structure, metal wiring can be formed in one exposure and etching process.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

This embodiment is applied to the case of forming metal wiring on the circuit board shown in FIG. 3 mentioned above, and the forming process is shown in FIG. 1. Note that the same parts as in FIG. 4 are given the same reference numerals.

First, as shown in Figure 1 (, ), copper,
A metal layer 5 of a predetermined thickness made of a conductive metal such as aluminum is formed in layers, and a positive photoresist 6 is deposited on the surface of the metal layer 5 in layers.

Next, as shown in FIG. 1(b), a photomask 12 is placed above the photoresist, and the photoresist 6 is exposed to ultraviolet light through the photomask 12. The photomask 12 has a mask 14.14 made of an opaque film such as chromium formed on the surface of a transparent plate 13 in correspondence with the metal wiring of the circuit board. This mask 14.14 includes portions 14m and 14h where the electrodes 2 and 2 of the metal wiring are formed and a portion 14b where the leads 3 and 3 are formed.
, 14b are completely light-shielded, and the portion 14C914C-i forming the thin wiring portion 4°4 is partially light-shielded. The thin wiring forming portions 14c, 14c form a pattern in which a large number of fine light-shielding portions and a large number of fine light-transmitting portions are uniformly mixed and dispersed, and specifically, as shown in FIG. 2 (-). There are mesh patterns as shown, speckled gloss turns as shown in FIG. 2(b), and even striped patterns (not shown).

By performing exposure using this photomask 12, the photoresist 6 is exposed to the mask 14.14.
electrode forming portions 14h, 14- and lead forming portions 14b.
, 14b is not irradiated with light, and in the portion covered with thin wiring forming portions 14a and 14c, the portions that are not irradiated with many fine lights and the portions that are irradiated with many fine lights are uniform. The light is dispersed in the other parts, and the other parts are irradiated with light.

Next, as shown in FIG. 1(c), development is performed using a developer to remove the portions of the photoresist 6 that were irradiated with ultraviolet rays in the exposure step. Accordingly, the mask 14
．． 14 electrode forming portions 14m.

14a, lead forming portions 14b, all portions of the photoresist 6 covered with 14b remain, and thin wiring forming portions 14
In the portion of the photoresist 6 covered with c and 14c, a large number of fine through holes 15 are uniformly distributed.

Next, as shown in FIG. 1(d), the metal layer 5 is etched using an etching solution. In this case, iJ? of said mask 14.14? Except for the portion of the metal layer 5 corresponding to the photoresist 6 remaining according to the turn, the other portions of the metal layer 5 are removed in the entire thickness direction.

In addition, the thin wiring forming portion 14c of the mask 14°14,
14c, the portion of the metal layer 50 corresponding to the remaining photoresist 6 is half-etched and formed into a thin layer. That is, since a large number of through holes 15 are dispersedly formed in the portions of the photoresist 6 corresponding to the thin wiring forming portions 14c and 14e of the mask 14.14, the etching solution is applied to these through holes 15. . . . reaches the metal layer 5 through the metal layer 5 and erodes the metal layer 5. However, there is a limit to the amount of etching solution that reaches the metal layer 5 through the through holes 15 of the photorenostro, and the erosion of the metal layer 5 progresses slowly. As a result, the erosion stops when about the upper half of the thickness of the metal layer 5 is removed, and about the lower half of the thickness of the metal layer 5 remains. Therefore, in the etching process for this metal layer 5, both normal etching and half etching can be performed at the same time.

Finally, the remaining photoresist 6 is peeled off as shown in FIG. 4(,). With this, the electrode 2 is placed on the surface of the substrate 1.
2. Metal wiring consisting of leads 3.3 and thin wiring portions 4.4 can be formed.

Therefore, by forming metal wiring in this way, 1
Both the thick wiring portion and the thin wiring portion of the metal wiring can be simultaneously formed in one exposure, development, and etching process.

In the above-described embodiments, a positive type photoresist is used, but the present invention is not limited to this, and a negative type 7 photoresist can also be used. in this case,
In the photomask, the mask for forming the thick wiring portion of the metal wiring is formed in 9 turns of all through holes.

〔Effect of the invention〕

-1r As explained above, according to the method for manufacturing a circuit board of the present invention, both the thick wiring part and the thin wiring part of the metal wiring can be formed simultaneously in one exposure, development and etching process. With fewer manufacturing steps, it is possible to easily and economically manufacture a circuit board provided with metal wiring having thick wiring portions and thin wiring portions.

[Brief explanation of the drawing]

Figure 1 (aJ~(,) is a process diagram showing an example of the manufacturing method of the present invention, Figure 2 (-) (b) is an explanatory diagram showing the pattern of a photomask, and Figure 3 is an illustration of a circuit board. A cross-sectional view showing an example, and FIGS. 4(1) to 4(j) are explanatory diagrams showing an example of a conventional circuit board manufacturing method. 1... Board, 2... Electrode, 3... Lead , 4...
-Thin wiring section, 12...photomask, 14...mask. Applicant's representative Patent attorney Takehiko Suzue Figure 1 1l- (a) (b) Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A method for manufacturing a circuit board in which a metal wiring consisting of a thick wiring portion and a thin wiring is formed on a substrate, the method comprising: patterning the metal wiring on a metal layer formed on the substrate; A method of manufacturing a circuit board, comprising using a photomask having a mask pattern in which a portion corresponding to a thick wiring portion is completely light-shielded or completely transparent, and a portion corresponding to a thin-walled wiring portion is partially light-shielding.