JPH0553067B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a pin grid array, and particularly to a pin grid array having a thin plastic film as a substrate.

(Prior technology) Traditionally, dual in-line packages (hereinafter referred to as DIPs) have been the most popular package for semiconductor devices, but with the recent increase in the integration density of LSI chips and the miniaturization and high performance of electronic devices, As demand increased, the number of pins in devices increased, and DIP had the problem of not being able to handle this increase as there was a limit to the increase in the number of pins. For this reason, pin grid arrays in which multiple rows of pins are erected on a ceramic substrate have recently been developed and put into practical use.

(Problem to be solved by the invention) However, the conventional pin grid array
Since a ceramic substrate is used, there are problems in that the cost is high, the substrate becomes large, and it is difficult to miniaturize the circuit. For this reason, pingrid arrays have been developed using relatively inexpensive plastic substrates 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 conduction has problems such as increasing the manufacturing process such as bonding process and sealing process of the joint part, as well as making the pin grid array thinner as with ceramic substrates. was difficult.

As a means to solve the above problem, the present inventor has provided the following:
a plastic film substrate having an opening and a wiring pattern formed on its surface; a plurality of pins standing upright on the film substrate and connected to the wiring pattern; We have developed a pin grid array, which consists of arranged metal heat sinks, and is made by integrally molding the film substrate together with the periphery of the heat sink and the pins using a heat-resistant resin.

However, in this pin grid array, the board is made of a thin plastic film with low mechanical strength, so the bonding strength between the board and the pins is weak, and even if the wiring pattern and pins are soldered, the wiring pattern on the board Since the bonding strength is low, it does not contribute to improving the bonding strength between the pin and the board, and if surface bonding method using soldering is adopted, the soldering process becomes complicated and a cleaning process is also required after processing. It became clear that there were some problems.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to increase the bonding strength between a plastic film substrate and pins, thereby making it possible to manufacture a highly reliable and highly accurate pin grid array at low cost.

(Means for Solving the Problems) As a means for solving the above-mentioned problems, the present invention provides a substrate made of a plastic film with a wiring pattern formed on its surface, and a plastic film inserted into each through-hole passing through the substrate and the wiring pattern. In a pin grid array comprising a plurality of pins fixed and connected to the wiring pattern, and a resin sealing part that encapsulates and integrates the board and the insertion side of the pin inserted and fixed to the board, the through hole A pin having a stepped portion on the insertion end side is used, and the substrate and wiring pattern are held between the stepped portion and a head formed on the insertion end side.

In a preferred embodiment, 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 each other by a stepped pin fitted into the through hole. It is held between the stepped part and the head.

(Function) The present invention uses a pin with a step on the head side, fits the head into a through hole penetrating the film substrate and the wiring pattern, and caulks the tip to connect the step and the head. When the board and wiring pattern are held together,
The wiring pattern mechanically reinforces the board, contributing to improving the bonding strength between the pins and the board, and the pins are attached to the film board and connected to the wiring pattern at the same time. In addition, a metal ring is formed coaxially with the through hole on the opposite surface of the wiring pattern formed on one surface of the film substrate, and when these are sandwiched between the stepped part and the head of the pin, the film substrate is connected to the metal ring and the wiring. It is reinforced by being held between the pins and the pattern, and improves the degree of bonding between the pins and the substrate when the pins are inserted and fixed in an upright position. Further improve reliability.

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

The figure shows an embodiment of a pin grid array according to the present invention, in which 1 is a film substrate made of a plastic material such as polyimide resin or epoxy resin;
3 is a stepped pin made of a metal material with good conductivity, 3 is a heat sink made of a metal material with good thermal conductivity such as copper or aluminum, and 4 is a sealing part that seals the film substrate, pin and heat sink together, and is made of polyphenylene. It is made of heat-resistant resin such as rensulfide and 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. and film substrate 1
A plurality of through holes 7 are formed through the. The wiring pattern 6 on the film substrate 1 has a ring portion 6a formed coaxially with the through hole 7, and on the surface of the film substrate 1 opposite to the wiring pattern 6,
A metal ring 8 is formed coaxially with the through hole 7 and having the same shape as the ring portion 6a of the wiring pattern 6.

The stepped pin 2 has a large diameter portion 2a forming a step near one end, and after the one end is inserted into the through hole 7 of the film substrate 1, the one end is caulked to form a head 2b. , is fixed to the film substrate 1 by sandwiching the metal ring 8, the film substrate 1, and the wiring pattern 6 between the head 2b and the large diameter portion 2a, 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 5 on the side facing the opening 5 of the film substrate 1, and a protrusion 10 on the peripheral edge 3a. The film substrate 1 and the pins 2 are integrally formed by sealing and molding the film substrate 1 and the pins 2 with heat-resistant resin. In addition, 11 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 or mother board. Each of them is integrally molded with the sealing 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 portion 4 includes the head 2b of the pin 2.
A hole 12 is formed that reaches this hole 12.
is the movable pin 1 that presses and fixes the pin 2 during encapsulation molding.
9. 20 is a heat sink 3 and a sealing part 4
This is a moisture-proof protective film that prevents moisture from entering through the joints.

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 1, 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 to light, it is etched by a known method to form the wiring pattern 6 and the metal ring 8. Next, after dissolving and removing the photoresist, gold plating is laminated on the wiring pattern 6 using nickel plating as a base layer by electroplating, and further, through-holes are formed and drilling and cutting to predetermined dimensions are performed. .

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, and the wiring pattern may be coated with silver plating or other corrosion-resistant and highly conductive materials. It may be formed by metal plating.

Furthermore, 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 metal ring 8
The base of the metal ring 8 and the wiring pattern 6 is formed by screen printing resist ink to mask the parts other than the parts where the wiring pattern 6 is to be formed, and then applying copper plating using a chemical copper plating method. In this method, the wiring pattern is completed by laminating electrolytic copper plating and electrolytic silver plating on top of the copper plating. In this case, since the surface of the wiring pattern 6 and the surface of the resist ink layer can be formed on the same level, a smooth film substrate with no unevenness on the surface can be obtained, and no burrs are formed during encapsulation molding.

To attach pins to the film substrate 1,
A stepped pin 2 prepared in advance may be inserted into the through hole 7 of the film substrate 1, and the end portion of the pin 2 that will become the head 2b may be caulked by vibration or hammering. As a result, the metal ring 8, the film substrate 1, and the wiring pattern 6 are sandwiched between the head 2b and the large diameter portion 2a of the pin 2, and the pin 2 is fixed to the film substrate 1, and the wiring pattern 6
electrically connected to.

Thereafter, as shown in FIG. 4, the lower mold 15 is placed in the cavity 17, the heat sink 3 is set so as to cover the opening of the film substrate 1, the upper mold 18 is lowered to close the mold, and the heat resistant Cavity resin 17
A pin grid array having the structure shown in FIG. 1 can be manufactured by injecting and encapsulating the resin, and then coating the exposed surface of the heat sink 3 with epoxy or polyimide resin.

Note that the shape of the pin does not necessarily have to be a single step, and as shown in FIG.
c, two or more step portions are provided, and the resin wraps around the space between two adjacent step portions, that is, the annular groove 2c, and the pin 2 and the resin sealing portion 4 are
The bonding strength with the pin and 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, the plastic film substrate is held between the stepped portion and the head of the stepped pin together with the wiring pattern formed on its surface. , the wiring pattern plays the role of reinforcing the plastic film,
The pins can be firmly fixed without deforming the plastic film substrate, improving the bonding strength between the substrate and the pins, and improving the reliability of the pin grid array.

Furthermore, if a metal ring is formed on the opposite side of the board from the wiring pattern, and the pin is fixed to the board with the metal ring and the wiring pattern interposed, the metal ring and the wiring pattern will reinforce the board. Deformation of the film substrate is prevented when the pins are caulked, a situation in which the film substrate cannot be held is prevented from occurring, and the bonding strength between the pins and the substrate can be further improved. Therefore, even if it is a thin plastic film substrate, it can be integrally molded with pins and a heat sink, making it possible to make the pin grid array thinner and lower in cost.Moreover, it has high dimensional accuracy of about 50 μm and is reliable. An excellent effect can be obtained in that a pin grid array with a high pin-grid array can be manufactured.

[Brief explanation of the drawing]

1 is a sectional view of a pin grid array according to the present invention, FIG. 2 is a partially enlarged sectional view thereof, and FIG. 3 is a plan view of a film substrate used for manufacturing the pin grid array of FIG. FIG. 4 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. DESCRIPTION OF SYMBOLS 1... Film substrate, 2... Pin, 2a... Large diameter part, 2c... Annular groove, 3... Heat sink, 3a...
Peripheral part of heat sink, 4... Resin sealing part, 5... Opening, 6... Wiring pattern, 7... Through hole, 8...
Metal ring, 10...protrusion.

Claims (1)

[Scope of Claims] 1. A substrate made of plastic film with a wiring pattern formed on its surface, a plurality of pins inserted and fixed into through holes penetrating the wiring pattern of the substrate and connected to the wiring pattern, and the substrate. and the insertion side of the pin inserted and fixed into the substrate, the pin has a stepped part on the insertion end side into the through hole, and the stepped part and the insertion end side are provided. 1. A pin grid array comprising: a head formed on a pin sandwiching the substrate and the wiring pattern; 2. The substrate has a metal ring formed coaxially with the through hole on the surface opposite to the wiring pattern, and the metal ring, the substrate and the wiring pattern are held between the stepped portion and the head of the pin. A pin grid array according to claim 1. 3. The pin according to claim 1 or 2, wherein the pin has an annular groove in a large diameter portion forming a stepped portion, and the stepped portion including the annular groove is sealed in a resin sealing portion. Pin grid array.