JPH0341998B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a printed wiring board for thin IC cards, and more particularly, the present invention relates to a thin multilayer printed wiring board for IC cards on which electronic components such as semiconductors are mounted. .

Printed wiring boards for IC cards are used for various purposes such as cash withdrawal cards called CD cards, recognition cards called ID cards, medical medical records called MC cards, and telephone cards called TCs. It is something that will be done.

(Prior technology) Conventional printed wiring boards for IC cards mount electronic components such as semiconductors on a horizontal board on the same level as the conductor circuits formed on a smooth horizontal board, and wire bond them. It was electrically connected.

As a result, there is a protrusion corresponding to the thickness of the semiconductor product, and contrary to the demand for thin printed wiring boards for IC cards and the card surface to be a smooth horizontal surface, unevenness on the product surface cannot be avoided. .

On the other hand, when increasing the density of printed circuit boards for IC cards by adding multiple functions, the thickness of the conductive plating in parts of the conductor circuits and through-holes is usually reduced.
By forming various plating layers such as copper plating, nickel plating, and gold plating, the thickness ranges from maximum 50μm to minimum 16μm.
This results in a film thickness of about m, and the thickness of the conductive plating on the land formed in the through-hole area also becomes particularly thick, which impedes smoothing of the surface of the IC card and makes it difficult to make the product thinner.

In particular, in lands, the plating current density tends to be high depending on the shape of the lands, and as a result, the lands tend to protrude in proportion to other parts, and that part cannot help but become thicker.

(Problems to be Solved by the Invention) As mentioned above, in conventional printed wiring boards for IC cards, when multilayering occurs, the plating thickness of the lands is added by the number of boards, and this is especially true for multilayer circuit boards. The land provided at the end of the contact through hole that conducts the entire structure will protrude to the back side of the IC card.

However, since the IC card must pass through a certain narrow gap, if the land portion provided at the end of the contact through hole protrudes, it will cause problems in terms of electrical contact.

Therefore, the present invention absorbs the protrusion of land portions such as contact through holes of the conventional printed wiring board for IC cards by some method and forms the same horizontal plane as the other portions.
The purpose is to eliminate and improve the shortcomings of printed wiring boards for IC cards.

Therefore, according to the present invention, at least the plating layer of the land provided at the end of the contact through hole is absorbed so that it does not protrude, and its thickness can be reduced, and chip electronic components such as semiconductors can be It is possible to provide a printed wiring board for an IC card that is housed in a recess (inside a cavity) in the board and that prevents sealing resin from flowing out to the outer periphery of the recess.

(Means and effects for solving the problems) In order to solve the above problems, the means taken by the present invention are as follows. A surface layer 1A having a metal plated part 2A consisting of an external connection terminal and at least six or eight contact through holes 3B is inserted into the front and back sides of an intermediate layer 1B having a mounting recess 1D, and an electronic component is inserted therein. In a printed wiring board for a thin IC card, the back layer 1C is formed of a resin substrate and each layer is integrated with an adhesive layer. Forming a contact through hole 3B for electrically connecting the conductor circuit to be connected and the metal plating portion 2A on the surface layer side, and a land 4 located at the end of each of these contact through holes on the back layer side, A thin type product characterized in that a recess 6 is formed on the back layer by counterbore processing at a portion corresponding to the land 4 on the intermediate layer side and absorbs the thickness of the land.
"Printed wiring board for IC cards."

In specifically explaining the printed wiring board for an IC card of the present invention, it will be explained in detail based on the drawings.

FIG. 1 is a perspective view of a printed wiring board for a thin IC card according to the present invention, and FIG. 2 is a longitudinal sectional view substantially corresponding thereto. 1 is a printed wiring board, and the most typical ones include a gallus fiber reinforced epoxy resin board, a paper phenol resin board, a paper epoxy resin board, a glass polyimide resin board, and a glass triazine resin board. A copper coating such as copper foil 10 must be formed on both sides of these substrates in advance.

Reference numeral 1A is the surface layer of the substrate 1, on which a metal plating layer 2A, which mainly serves as external connection terminals of the IC card, is formed.

Reference numeral 1B is an intermediate layer of the first substrate, in which a plurality of through holes 3A and semiconductor mounting recesses 1D are mainly formed.

1C is the inner and rear surface layer of the substrate 1, in which a recess 1E for preventing the sealing resin from flowing out and a recess for absorbing the land thickness are mainly formed.

Further, a conductor circuit 2B for bonding the semiconductor is formed near the semiconductor mounting recess 1D provided in the intermediate layer 1B, and a contact through hole 3B is formed to conduct the intermediate layer 1B and the surface layer 1A. A land 4 is formed at one end thereof.

5 is an adhesive layer for bonding the substrates together. The adhesive layer 5 may be an uncured epoxy resin-containing glass cloth, a heat-resistant adhesive sheet, a liquid resin, or the like, and preferably has high adhesive properties such as adhesiveness, heat resistance, and durability.

What is important here is that the back layer 1C in which the sealing resin outflow prevention recess 1E is formed, the intermediate layer 1B in which the semiconductor mounting recess 1D is formed, and the surface layer 1A are bonded together using the adhesive layer 5. This is done by semi-curing the adhesive layer 5 and then temporarily pressing it so that the adhesive layer 5 does not flow into the previously formed recesses. The conductor circuit 2B formed on the intermediate layer 1B and the metal plating portion 2A formed on the surface layer 1A must be nickel-plated or gold-plated in order to use the adhesive layer 5 after being semi-cured in this way. Especially contact through hole 3B
Copper plating, electrolytic nickel plating, and electrolytic gold plating were applied to the area twice in total.In particular, land 4 was plated twice, and as mentioned above, due to the high current density and the thickness of 16 to 50 μm. It stood out.

The most important feature of the present invention is the means for absorbing the thickness (t) of various plating layers. This was done by noting that the base material thickness of the back layer 1C is relatively thick at 0.2t, and that the adhesive on the land 4 portion is not necessary. By forming a concave part by counterbore processing in the contacting part, or by removing the adhesive in that part and bonding the substrates together, the thickness (t) of various plating layers can be absorbed and the thickness can be reduced and the land can be reduced. This is a completed printed wiring board for thin IC cards in which the four parts protrude and are not directly exposed on the back surface.

(Example) Next, the most typical example of the present invention will be described.

Example 1 The intermediate layer has a thickness of 0.1 mm (hereinafter mm thickness is referred to as t).
Similar to double-sided printed wiring boards, using a printed wiring board (denoted as ), after drilling holes, plating copper through holes, forming patterns, etching, SR printing, electrolytic nickel plating, and electrolytic gold plating, adhere to the surface opposite to the bonding surface. After temporarily adhering the adhesive layer, the semiconductor mounting portion is punched out. For the back side of the surface layer, a 0.165t printed wiring board is used, and as with single-sided printed wiring boards, drilling, patterning, etching, etc.
Apply electrolytic nickel and electrolytic gold plating. This side is
This is the mounting surface for semiconductors. Next, after adhering the intermediate layer and the surface layer by hot pressure pressing, 6 or
Holes for eight contact through holes were drilled, copper through hole plating, patterning, etching, electrolytic nickel and electrolytic gold plating were performed. At this time, the land of the contact through hole portion of the bonding surface is plated twice with copper, electrolytic nickel plating, and electrolytic gold plating, and this land portion is approximately 40 μm thicker than the thickness of the bonding terminal.
It becomes moderately thick.

The back layer uses a 0.2t printed wiring board,
(Printed wiring board from which all copper foil has been removed)
After applying a reverse counterbore process to the part that contacts the contact through-hole part, which is larger than the land, to form a part that absorbs the reverse land thickness of the concave part, adhesive is temporarily bonded to this part to prevent the sealing resin from flowing out. Punch out a recess for use.

Next, the intermediate layer, the front layer, and the back layer were bonded together using a hot pressure press, and then punched into a desired shape to obtain a printed wiring board for an IC card of the present invention as shown in FIG. 3.

Example 2 The intermediate layer was made using a 0.1t printed wiring board, and the bonding surface was formed by drilling holes, copper through-hole plating, pattern formation, etching, SR printing, electrolytic nickel, and electrolytic gold plating in the same way as for double-sided printed wiring boards. After temporarily bonding an adhesive layer to the opposite side, punch out the semiconductor mounting part. The surface layer and back side are
Using a 0.065t printed wiring board, perform drilling, pattern formation, etching, electrolytic nickel plating, and electrolytic gold plating in the same way as a single-sided printed wiring board.
This surface becomes the mounting surface for the semiconductor. Next, the above
After bonding the intermediate layer and the surface layer by hot pressure pressing, holes for six or eight contact through holes are formed, copper through hole plating, patterning, etching, and electrolytic nickel and electrolytic gold plating are performed. At this time, the land of the contact through hole portion of the bonding surface is plated twice with copper, electrolytic nickel plating, and electrolytic gold plating, and this land portion becomes approximately 40μ thicker than the thickness of the bonding terminal.

The back layer uses a 0.2t printed wiring board,
(Printed wiring board from which all copper foil has been removed)
After performing a counter-corrosion process larger than the land on the part that contacts the contact through-hole part, this part is temporarily bonded with the removed adhesive, and a concave part for preventing the sealing resin from flowing out is punched out.

Next, the intermediate layer, the front layer, and the back layer were bonded together using a hot pressure press, and then punched into a desired shape to obtain a printed wiring board for an IC card of the present invention.

The printed wiring board for thin IC cards of the present invention is basically composed of a surface layer, an intermediate layer, and a back layer as described above, but depending on the type of IC card,
Depending on the application, multi-functionality and high density are required, so the number of intermediate layers may be increased to two or more layers, or the metal plating layer formed on the surface layer or the sealing layer formed on the back layer. The number and shape of the recesses or holes for preventing resin outflow can be changed as appropriate.

(Effects of the Invention) As described above, in the printed wiring board for an IC card of the present invention, at least the thickness of the land portion can be made thinner by various methods, and a recess is formed in the semiconductor mounting portion so that the semiconductor can be attached to the substrate. It has a structure that does not protrude above the surface, and furthermore, a stepped recess is formed in the resin-sealed part of the semiconductor so as to be connected to the recess in the semiconductor mounting part, so that the sealing resin can be prevented from flowing out.
Moreover, the thickness of the printed wiring board is made as thin as possible by creating a structure in which the thickness of the resin layer does not protrude from the surface, and a structure in which the land and circuit parts are not directly exposed on either the back surface. This is an optimal structure for use as a substrate.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a printed wiring board for an IC card according to the present invention, FIG. 2 is a vertical sectional view of a part of the printed wiring board for a thin IC card according to the present invention, and FIG. 3 is a perspective view of a printed wiring board for a thin IC card according to the present invention. FIG. 2 is a longitudinal cross-sectional view showing an embodiment of land thickness absorption of a printed wiring board. In the above drawings, 1... printed wiring board, 1A... surface layer, 1B... intermediate layer, 1C...
Back layer, 1D...Semiconductor mounting recess (cavity), 1E...Recess for sealing resin outflow prevention, 2A
...Metal plating part, 2B...Semiconductor connection line conductor part, 3A...Through hole, 3B...Contact through hole, 4...Land part, 5...Adhesive layer, 6...Concave part for absorbing land thickness, 7...Land thickness absorption hole.

Claims (1)

[Scope of Claims] 1. A conductive circuit connected to an electronic component to be mounted, and a metal plating portion serving as an external connection terminal on the front and back sides of an intermediate layer having a recess for mounting a semiconductor for the electronic component, A surface layer having at least six or eight contact through holes and a back layer having an opening for inserting the electronic component are formed from a resin substrate, and these layers are integrated by an adhesive layer. In the printed wiring board for a thin IC card configured, the intermediate layer includes a contact through hole for electrically connecting the conductor circuit connected to the electronic component and the metal plating part on the surface layer side, and each of these a land located at the end of the contact through hole on the back layer side; and a recess located in the back layer at a portion corresponding to the land on the intermediate layer side to absorb the thickness of the land. A printed wiring board for thin IC cards, characterized in that it is formed by counterbore processing.