JPH0474865B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming electrical connection protrusions on a substrate used to obtain electrical connection between an electrode of an electronic component element such as a semiconductor element and an external substrate. Regarding the manufacturing method.

[Conventional technology]

Conventionally, as shown in FIG. 2, as shown in Japanese Patent Application Laid-Open No. 59-17981, as a method for manufacturing a protrusion for electrical connection to the inner lead of a tape carrier board, for example, (a) a protective resist is coated on the surface of the conductor layer 2. (b) forming protrusions 6 on the back surface of the conductor layer 2 by applying photoresist 3, exposing, developing, and half-etching; (c) coating the protective resist 71 on the front and back surfaces of the conductor layer 2; and (d) coating the photoresist 31 on the surface of the conductor layer 2.
A patterning step consisting of exposure and development; (e) a step of applying a protective resist 72 to the back surface of the conductor layer 2; and (f) a step of etching the surface of the conductor layer 2 to form a circuit pattern including the inner leads 8. (g) The protrusion 6 was manufactured on the back surface of the inner lead 8 by a step of peeling off the photoresist 31 and the protective resist 72 on the front and back surfaces of the conductor layer 2.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology, the surface of the conductor layer 2
Since the back side is exposed separately, it is not easy to form the protrusion 6 at a predetermined position on the inner lead 8 due to a positioning error of the substrate during exposure. Especially when exposure is performed automatically and continuously, such as with tape carrier substrates, although it is possible to align the front and back patterns initially, it is difficult to align each substrate after that. This is not possible, and depending on the substrate positioning accuracy of the exposure machine, deformation of the sprocket hole 5 serving as a reference hole, etc., it may cause bonding failure due to missing protrusions or misalignment with the semiconductor element electrode. Furthermore, in the conventional technology, the conductor layer 2 is half-etched and subjected to steps such as photoresist coating, exposure, and development in a weakened state, so the conductor layer is easily deformed, resulting in wire breakage due to photoresist cracks, etc. However, there is a problem in that good pattern formation cannot be stably performed.

The present invention is intended to solve these problems, and its purpose is to eliminate misalignment between leads and protrusions, reduce damage to the conductor layer by shortening the process, and improve pattern formation. An object of the present invention is to provide a method for manufacturing protrusions on a substrate conductor layer that stably enables the production of protrusions on a substrate conductor layer.

[Means for solving problems]

The method of manufacturing protrusions on a substrate conductor layer according to the present invention includes: an insulating layer made of a resin material in which an opening into which an electronic component is inserted; and a metal foil adhered on the insulating layer so as to cover the opening. a substrate conductor layer consisting of a conductor layer and a conductor layer, a first step of applying a photoresist on both sides of the conductor layer, and simultaneous exposure and development of the photoresist on both sides of the conductor layer for patterning. a second step, a third step of etching the conductor layer from both sides and half-etching so as to leave a portion of the conductor layer; and a third step of applying a protective resist to the back side of the half-etched conductor layer. a fifth step of etching the half-etched conductor layer from the surface; and a sixth step of peeling off the photoresist and the protective resist, A feature is that protrusions are formed on the conductor layer.

〔Example〕

Hereinafter, the present invention will be described in detail based on examples.

FIG. 1 is an embodiment of the present invention, and is a diagram showing the sequence of steps for forming electrical connection protrusions on inner leads of a tape carrier substrate. First, Fig. a shows a step of applying photoresist 3 to both sides of a conductor layer 2 pasted on an insulating layer 1. Here, insulating layer 1
is a flexible tape made of polyimide or glass epoxy with a thickness of 25 μm to 125 μm, and has device holes 4 for electronic components such as semiconductor devices, sprocket holes 5 used for positioning and transportation, and other holes necessary for circuits. There is. The conductor layer 2 is usually a copper foil with a thickness of 35 μm to 70 μm, and its back surface is treated to have irregularities with a surface roughness of about 10 μm to improve adhesion to the insulating layer 1. This unevenness is
It remains on the surface of the protrusions formed in the subsequent process, and has the effect of breaking through the Al oxide film and increasing the bonding strength when bonding with the Al electrode of the semiconductor element, making it possible to maintain the initial surface roughness. is important. Therefore, the thickness of the photoresist on the back surface of the conductor layer 2 must be set to a thickness of 1.5 μm to 4 μm so that the convex portions are not etched during half etching, which will be described later, and so that it is not too thick and uneven. is appropriate. On the other hand, the thickness of the photoresist on the surface is normal.
The thickness is 1 μm to 3 μm, and a roll coater or spray is used for both the front and back sides.

Next, as shown in Figure b, a circuit pattern including inner leads is formed on the front surface of the conductor layer 2 using a photomask as shown in Figure 3, and a protrusion pattern is formed on the back side using a photomask as shown in Figure 4. Both sides are exposed and printed at the same time using a double-sided exposure device that is adjusted to be in a predetermined position with respect to each other, and then both sides are simultaneously developed by spraying or dipping using a special developer. Here, the photomask shown in FIG. 3 is designed so that the circuit pattern including the inner leads are all electrically conductive so that electroplating can be performed in a subsequent process. In addition, as a photomask for printing the protrusion pattern, in addition to a photomask with individual protrusion patterns corresponding to the inner leads as shown in Fig. 4, a photomask with some or all protrusions connected as shown in Fig. 5 is used. It is also possible. Furthermore, in order to bring both sides into a proper developing state at the same time, the exposure amount is adjusted.If the photoresist thickness on both sides is the same, the back side, which has a large surface roughness and is difficult to develop, has a roughness of 1.5 to 2.5 times that of the front side. It is better to set it to the amount of exposure.

Next, as shown in figure c, both sides of the conductor layer 2 are coated with dichloride.
Half-etch by spraying an etching solution such as iron. Here, the height of the protrusion 6 on the back surface of the conductor layer 2 varies depending on the thickness of the conductor layer used.
Usually, in the case of 35μm copper foil, it is used to prevent edge-cutting of semiconductor elements and to ensure inner lead strength.
It is set to 5 μm to 20 μm. Furthermore, in order to prevent stress from concentrating on the corners of the half-etched part and making it easier to cut, the spray pressure is lowered and the side etching is increased so that a large radius is formed at the corner of the half-etched part, as shown in Figure 6. Usually specific gravity 30Be′~60Be′,
Spray pressure 0.5 with ferric chloride liquid at liquid temperature 25℃~40℃
Although half etching is performed at less than Kgf/ ^cm2 , the height of the protrusion 6 is 1/2 of the thickness of the conductor layer 2 used.
If it is less than that, half etching by dipping is also possible. In order to ensure the strength of the inner lead, by devising a photomask for printing the protrusion pattern on the back side, it is possible to continuously change the amount of half etching as shown in Figure 7, or to change the amount of half etching as shown in Figure 8. It is also possible to make it as short as possible. On the other hand, when half-etching the front surface of the conductor layer 2, an etching solution is sprayed on the back surface in order to prevent uneven etching due to the etching solution flowing around when half-etching the back surface. The amount of half etching at this time is adjusted by spray pressure or the like so that the portions etched from both sides do not penetrate through.

Next, as shown in Figure d, a protective resist 7 such as an etching resist or a photoresist that can be removed with the same stripping solution as the photoresist used in Figure A is applied to the back surface of the conductor layer 2 using a roll coater, spray, or the like.

Next, as shown in figure e, the unnecessary conductor layer that was not etched in the process of figure c is etched by spraying an etching liquid from the front side of the conductor layer 2 to form a circuit pattern including the inner leads 8. do.

Next, as shown in Fig. f, the photoresist 3 and the protective resist 7 are peeled off using a special stripping liquid, thereby completing a tape carrier substrate having inner leads 8 with electrical connection protrusions 6. Usually, after this, a plating process (not shown) is performed to apply nickel plating to 0 μm to 3 μm, and then gold plating to 0.5 μm to 2 μm.
Electrical connection can be made by attaching the electrode to the semiconductor element, positioning it with the electrode of the semiconductor element, and bonding it by thermocompression. FIG. 9 is a diagram showing a mounting structure of the tape carrier substrate 10 and the semiconductor element 11 according to the present invention.
is a resin sealant.

Although the above explanation took the tape carrier board as an example, it is not limited to the tape carrier board, but can be applied to any printed circuit board having inner leads for bonding electronic component elements.

〔Effect of the invention〕

As described above, according to the present invention, the structure includes the second step of simultaneously exposing, developing and patterning the photoresists on both sides of the conductor layer.
For example, if the patterns on both sides are aligned initially, it is possible to prevent relative misalignment. It becomes possible to always form the protrusion at a predetermined position on the conductor layer without causing any damage, and as a result, alignment between the electrode of the semiconductor element and the protrusion becomes easy, and a stable connection between the two becomes possible.

In addition, after the patterned substrate conductor layer is half-etched from both sides, a protective resist is applied to the back side, and it is etched again from the front side. Since the structure includes the third step, the protrusion formed by half etching is protected by the protective resist in that state, and only a part of the thinned conductor layer is etched again by half etching from both sides. For example, compared to conventional techniques in which patterns are formed and protrusions are formed by sequentially etching from only one surface, the processing steps are shortened, there is no deformation of the conductor layer, and there is no crack in the photoresist. Because there is no possibility of entering
Good and stable pattern formation becomes possible.

Furthermore, by shortening the process, manufacturing costs can be reduced.

[Brief explanation of drawings]

Figures 1a to 1f are process diagrams showing a method for manufacturing electrical connection protrusions to a tape carrier board according to an embodiment of the present invention, and Figures 2a to 2g are process diagrams showing a method for manufacturing electrical connection protrusions to a tape carrier board according to an embodiment of the present invention. 3, 4, and 5 are plan views of photomasks used in the embodiments of the present invention, and FIGS. 6, 7, and
FIG. 8 is a cross-sectional view showing the inner lead shape in an embodiment of the present invention, and FIG. 9 is a cross-sectional view showing a mounting structure of a semiconductor element using a tape carrier substrate in an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Insulating layer, 2... Conductor layer, 3, 31... Photoresist, 4... Device hole, 5... Sprocket hole, 6... Protrusion, 7, 71, 72... Protective resist, 8... Inner lead, 10... Tape carrier Substrate, 11...Semiconductor element, 12...Resin sealant.

Claims (1)

[Scope of Claims] 1. An insulating layer made of a resin material in which an opening into which an electronic component is inserted is formed, and a conductor layer made of a metal foil deposited on the insulating layer so as to cover the opening. a first step of applying a photoresist on both sides of the conductor layer; a second step of simultaneously exposing and developing the photoresist on both sides of the conductor layer to pattern it; a third step of etching the conductor layer from both sides and half-etching the conductor layer so as to leave a portion of the conductor layer; a fourth step of applying a protective resist to the back surface of the half-etched conductor layer; A fifth step of etching the etched conductor layer from the surface, and a sixth step of peeling off the photoresist and the protective resist, and a protrusion is formed on the conductor layer located in the opening. A method for manufacturing protrusions on a substrate conductor layer, characterized in that: