JPS6240754A - Pin mounting structure of pin grid array - Google Patents

Abstract

PURPOSE:To reduce the thickness and cost of a pin grid array by interposing a film substrate and a wiring pattern between the step and the head the head of the stepped pin engaged within a through hole of the substrate. CONSTITUTION:A stepped pin 2 has a large-diameter portion 2a for forming a step near one end side, the one end side is engaged with a through hole 7 of a film substrate 1, and the one end side is then calked to form a head 2b. A metal ring 8, the substrate 1 and a wiring pattern 6 are interposed between the head 2b and the portion 2a to be secured to the substrate 1, and electrically connected with the pattern 6. Thus, a pin grid array of the substrate made of plastic film can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a structure for attaching pins to a pin grid array, and particularly to a structure for attaching pins to a thin plastic film substrate.

(Prior art) Traditionally, dual in-line packages (hereinafter referred to as DIPs) have been the most popular semiconductor device package, but recently, LSI chips have become more highly integrated, and electronic devices have become smaller and more sophisticated. The number of pins in devices has increased due to the increasing demand for devices, and since there is a limit to the increase in the number of pins in DTP, recently, a pin IJ array, which has multiple rows of pins on a ceramic substrate, has been developed and put into practical use. It has been provided.

(Problems to be solved by the invention) However, since conventional pin grid array packages use ceramic substrates, they are expensive, and it is difficult to increase the size of the substrate and miniaturize the circuits. There is a problem. For this reason, relatively inexpensive plastic pin grid arrays have been developed using printed wiring board technology, but high precision cannot be obtained without strict control during the manufacturing process. Incorporating a metal heat sink to increase the heat dissipation rate increases the number of manufacturing steps such as bonding and sealing of joints, and, like those using ceramic substrates, it is difficult to make the pin grid array thinner. there were.

As a means to solve the above problem, the present inventor has proposed a film substrate having an opening and having a wiring pattern formed on its surface;
It consists of a plurality of pins erected on the film substrate and connected to the wiring pattern, and a metal heat sink arranged on the film substrate so as to cover the opening of the film substrate, and the film substrate is connected to the heat sink. We proposed a pin grid array characterized by integrally molding the peripheral edge and pins with a heat-resistant resin. However, since the board is made of a glass film, the bonding strength between the film board and the wiring pattern is low. Therefore, soldering the pattern and pin does not improve its strength. In the case of surface bonding method using soldering, the soldering process is complicated and a cleaning process is required after the process.

(Means for Solving the Problem) As a means for solving the problem, the present invention provides a film substrate having a wiring pattern formed on its surface, and a pin inserted into each through hole passing through the film substrate and the wiring pattern. In the fixed pin grid array, the stepped pin fitted into the through hole of the film substrate has a stepped portion and a head that sandwich the film substrate and the wiring pattern. This provides a pin attachment structure.

In a preferred embodiment, a metal ring is formed coaxially with the 11 through holes on the surface of the film substrate opposite to the wiring pattern, and the metal ring, the film substrate, and the wiring pattern are connected to each other with a stepped ring fitted into the through hole. It is possible to clamp the pin between the stepped portion and the head.

(Function) The present invention makes it possible to swage the film of the pin by caulking the head of the pin so that the film substrate and the wiring pattern are held between the step and the head of the stepped pin fitted into the through hole of the film substrate. It is designed to be attached to the board and connected to the pin wiring pattern. In addition, by forming a metal ring coaxially with the through hole on the opposite surface of the wiring pattern formed on one surface of the film substrate, the metal ring, the film substrate, and the wiring pattern can be held together with pins. It was designed to improve strength. Moreover, this makes it possible to manufacture a pin grid array using a plastic film as a substrate.

(Example) Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

In the diagram showing an embodiment of the pin grid array according to the present invention, I is a film substrate made of a plus deck material such as polyimide resin or epoxy resin, 2 is a stepped pin made of a highly conductive metal material, and 3 is a copper or The heat sink is made of a metal material with good thermal conductivity such as aluminum, and 4 is a sealing part that integrally seals the film substrate, the pins, and the heat sink, and is made of a heat-resistant resin such as polyphenylene sulfide or epoxy resin.

The film substrate 1 has an opening 5 in its center, and a wiring pattern 6 extending radially from the vicinity of the opening 5 is formed on its surface, as shown in FIG. A plurality of through holes 7 are formed through the film substrate 1 . The wiring pattern 6 on the film substrate I has a ring portion 6a formed coaxially with the through hole 7, and on the surface of the film substrate I opposite to the wiring pattern 6,
Ring portion 6a of wiring pattern 6 coaxially with through hole 7
A metal ring 8 having the same shape is formed.

The stepped pin 2 has a large diameter portion 2 that forms a stepped portion near one end.
a, and after fitting one end side into the through hole 7 of the film substrate 1, the one end side is caulked to form a head 2b, and between the head 2b and the large diameter part 2a, a metal ring 8, Film substrate! By sandwiching the wiring pattern 6, it is fixed to the film substrate l and is electrically connected to the wiring pattern 6.

The heat dissipation plate 3 has a recess 9 having approximately the same area as the opening N5 on the side facing the opening 5 of the film substrate l, and a protrusion IO formed on the peripheral edge 3a, so that the peripheral edge 3a is connected to the film substrate l. The pin 2 is sealed with a heat-resistant resin and is integrated with the film substrate (2) and the pin 2. In addition, 1
1 is a standoff, which is used to leave a certain distance between the pin grid array and the mother board when it is attached to a pin socket, mother board, etc., and is sealed at each of the four corners of the pin grid array. It is integrally molded with part 4. Note that the standoffs 11 can be formed not only at the corners of the film substrate but also at any arbitrary position. In addition, the sealing part 4
A hole 12 reaching the head 2b of the pin 2 is formed in the hole 12, and this hole 12 is formed by a movable pin 19 that presses and fixes the pin 2 during encapsulation molding. Reference numeral 20 denotes a moisture-proof protective film for preventing moisture from entering through the joint between the heat sink 3 and the sealing portion 4.

The pin grid array having the above structure can be manufactured as follows. That is, copper foil is laminated on both sides of the base film of the film substrate l, a photoresist is applied on the surface of the copper foil and dried, and a wiring pattern is formed on one surface and a through hole 7 is formed on the opposite surface. After each metal ring pattern corresponding to the position to be formed is exposed, etching is performed by a known method to form the wiring pattern 6 and the metal ring 8.

Next, after dissolving and removing the photorenost, gold plating is laminated on the north side of the wiring pattern 6 using nickel plating as a base by electroplating, and through-holes are formed and punched and cut to a predetermined size.

In this example, nickel plating and gold plating are laminated on the wiring pattern formed by etching the copper foil, but it is not necessary to do so. It would be better if it was formed with metallic metal plating.

Further, the following method may be adopted as a method for manufacturing the film substrate 1. That is, the base film is slitted, degreased, and dried. Catalyst paste is applied to both surfaces of the base film to facilitate attachment of chemical copper plating. After drying, stamping is performed to form wiring patterns 6 and The metal ring 8 is formed by masking the areas other than the area where the metal ring 8 is to be formed by screen printing resist ink, and then applying copper plating using a chemical copper plating method.
In this method, the base of the wiring pattern 6 is formed, and the copper plating serving as the base of the wiring pattern 6 is laminated with electrolytic copper plating and electrolytic silver plating to complete the wiring pattern. In this case, since the surface of the wiring pattern 6 can be formed on the same level as the surface of the trace resist ink layer, a smooth film substrate with no irregularities on the surface can be obtained, and no flakes are formed during encapsulation molding.

To attach a pin to the film substrate 1, a stepped pin 2 prepared in advance is inserted into the through hole 7 of the film substrate 1, and the end of the pin 2, which will become the head 2b, is vibrated or hammered. Just caulk it. This results in
A metal ring 8 is provided between the head 2b of the pin 2 and the large diameter portion 2a.
Film substrate! and the wiring pattern 6 is sandwiched, and the pin 2
is fixed to the film substrate l, and the wiring pattern 6
electrically connected to.

After that, as shown in FIG. 4, the cavity I of the lower mold 15 is
Placed in 7, film substrate! The heat dissipation plate 3 is set so as to cover the opening of the heat dissipation plate 3, the upper mold 18 is lowered and the mold is closed, a heat-resistant resin is injected into the cavity 17 and sealed, and then the side where the heat dissipation plate 3 is exposed is closed. By coating the surface with epoxy or polyimide resin,
A pin grid array having the structure shown in FIG. 1 can be manufactured.

Note that the shape of the pin does not necessarily have to be one step, but as shown in Figure 5, two or more steps are provided so that the heat-resistant resin wraps around the space between the two steps.
The pulling force of the pin may be improved.

(Effects of the Invention) As is clear from the above description, according to the present invention, a metal ring is formed on the surface of the substrate opposite to the wiring pattern,
When the pin is caulked, the base film that forms the through hole is prevented from deforming, and a situation where the pin cannot be held is prevented. Therefore, a thin film substrate is used, and the film substrate is integrated with the pin and the heat sink. The pin grid array can be encapsulated and molded, the pin grid array can be made thinner and lower in cost, and moreover, the pin grid array can be manufactured with high dimensional accuracy of about 50 μm and high reliability.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a pin grid array according to the present invention, FIG. 2 is a partially enlarged sectional view thereof, FIG. 3 is a plan view of a film substrate used for manufacturing the pin grid array of FIG. 1, and FIG. 1 is a sectional view of a main part of a mold during encapsulation molding in the manufacturing process of the pin grid array shown in FIG. 1, and FIG. 5 is a sectional view of a main part of a pin grid array showing a modification of the present invention. 1-film substrate, 2-pin, 3-heat sink, 3a-periphery of heat sink, 4-heat-resistant resin, 5-opening, 6-wiring pattern, 7-through hole, 8-metal ring, lO- protrusion. wstai) Figure 2 Figure 4 Figure 5

Claims (2)

[Claims] (1) In a pin grid array consisting of a film substrate with a wiring pattern formed on its surface, and pins inserted and fixed in through holes penetrating the film substrate and the wiring pattern, the pins are inserted into the through holes of the film substrate. A pin mounting structure for a pin grid array, characterized in that a film substrate and a wiring pattern are held between a step portion and a head of a stepped pin. (2) A metal ring is formed coaxially with the through hole on the surface of the film substrate opposite to the wiring pattern, and the metal ring, the film substrate, and the wiring pattern are connected to the stepped portion of the stepped pin fitted into the through hole. A pin mounting structure for a pin grid array according to claim 1, wherein the pin grid array is held between a head and a head.