GB2295927A

GB2295927A - Mounting of an integrated circuit on a printed circuit board

Info

Publication number: GB2295927A
Application number: GB9424746A
Authority: GB
Inventors: Gareth Rhys Baron
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-12-08
Filing date: 1994-12-08
Publication date: 1996-06-12
Also published as: GB9424746D0

Abstract

Springs 3 on an integrated circuit package 1 make contact with pads 4 on a printed circuit board 2. Spring clips 5 hold the package 1 and a heat sink 7. A dust seal 8 may provide electromagnetic shielding. <IMAGE>

Description

THE 'SPRING CLIP GRID ARRAY FIELD OF THE INVENTION THIS INVENTION relates to the mounting of integrated circuit(s), herein after simply called, "IC", on a printed circuit board or a printed wiring board, herein after referred to as, "PCB" The invention consists of three distinct pans, the Spring Clip Grid Array IC Package, herein after referred to as 'SCGA", the Spring Clip Grid Array Holder, hereinafter referred to as, "SCGA Holder". and a thermal management method, herein after referred to as, "Heat Sink" BAC1;GROUND TO THE INVENTION Currently ICs are packaged in a compound which will protect the small piece of circuitry from the harsh chemical elemenis surrounding it.This compound is usually made up of a chemically inert compound which will seal the device in a vacuum or in a chemical which will not cause corrosion or other electrical defects to the device. This chemically inert package is usually known as the IC Body or IC Package and will be herein after referred to as "IC Package" Due to the technoloi ical advances and ever more higher circuitry integration onto ICs a packaging problem has arisen. The main problem consists of the ability to bring out the connections from the inside of the IC Package to the outside world where it can be connected to a PCB.

Thus the invention is aimed at the mounting of VLSI (Very Large Scale Integration) ICs and tJLSI (Ultra Large Scaie integration) devices on a PCB.

another problem of ICs is that thev generate a lot of heat when operational. A part of his invention provides for a heat sink.

OBJECT OF THE iNVENTION The object of this invention is to provide a better means of packaging for an IC and to allow for easier fitting of such a device to a PCB and/or to provide a better method of thermal management.

DESCRIPTION OF THE INVENTION According to this invention there is provided a SCGA packaging and an SCGA Holder and a Heat Sink..

To get a better 'feel' for the invention the reader is referred to the drawings (Figures 1, 2 and 3).

A BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of the invention is described below. by way of an example only, and with reference to the accompanying drawings in which Figure 1 - is a representation of SCGA Package Figure 2 is a slice-through projection the SCGA Package. the SCGA Holder and the PCB Figure; is an top view of the SCGA Holder with the PCB visible underneath the SCGA Holder.

The SCGA package (Figure 1) comprises of the IC package (1) which encases the IC and the Springs (3) which connect the IC to the PCB. kiso shown in Figure 1 is the PCB (2) and the SCGA Holder Nlounting Holes (12)..

The SCGA Holder is shown in more detail in Figure 2. This diagram shows a slicethrough projection of the SCGA the SCGA Holder and the Heat sink. The SCGA is connected to the PCB (2) by the means of the Springs (3) to the metal contacts on the PCB (4), herein after referred to as "Pads" The SCGA Package (1) is held in place by the Spring Clips (5). These Spring Clips are barbed so that the SCGA package will not lift off the PCB. The Spring clip (5) is connected to the PCB by solder (10). This solder will also hold the SCGA Holder frame (6) in place as the Spring clip will be bonded to it. A further part of the SCGA Holder (6) is the Dust Seal (8). One further feature of the SCGA is the Heat sink (7) and a thermal transfer compound (9) which is connected to it.

In Figure 3 the top view of the SCGA Holder can be seen. This consists of the SCGA Holder itself (6), the PCB (2), the Dust Seal (S), the Pads (4), the Spring Clip (5) and the location marker (11).

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO Tlì E DWWlNGS Referring to Figure 1, the IC Package (1) will be pressed against the PCB (2). The Springs underneath the IC Package (3) will compress and make an electrica! connection to the Pads (4) (not shown in Figure 1). The Pads (4) will then connect to the other components on the PCB via copper printed wire links herein after referred to as "Tracks" A further feature provides for the soldering of the Springs (3) to the PCB Pads (4). This may be done by a hot plasma soldering technique or another method of soldering.

The Spring (3) consists of an angled piece of metal, which has good electrical conductive and mechanical spring properties. The Spring is pressed against the Pads where it will form a good connection. When the Spring is soldered to the board the Spring will not be in a compressed state. This allows for the technique of surface mount soldering to a PCB (as the above paragraph).

Referring to Figure 2. the SCGA Holder consists of the Holder Frame (6) the Spring Clip (5) and the Dust Seal (8) which will seat the IC Package (1). As can be seen in the figure the Spring Clip (5) has barbs on it for ease of insertion. This is angled so that as the IC package gets further pushed into the SCGA Holder the latching mechanism becomes more tight. Thus giving the IC Package better retention in the SCGA Holder. This retention force is obtained from the pushino-up force from the Springs (3) against the Spring Clip (5) and hence will form a snug fit. It may be worth pointing out that the Spnng Clip (S) is heid in place by a solder joint (10). This also hoids the Holder Frame in place.

In Figure 2. The SCGA Holder also provides for a Heat Sink (7). This is so that the IC can be cooled off when operational. A heat transfer compound (9) should be mounted between the IC Package and the Heat sink so that there is a better thermal conductivity (this compound is beyond the scope of this document).

In Figure 2, The SCGA Holder also has a dust seal (8) on the Holder Frame. This is to stop any particles of dust from getting underneath the contacts and causing malfunction of the connections. This dust seal may be made of a spongy compound (such as rubber) which will not perish under normal operation conditions. Another feature of the Dust Seal is to provide Electro-magnetic shielding. In this case the Dust Seal must be conductive and be connected to a power point on the PCB via a Pad or some other electrical/magnetic connection. This may be through the SCGA Holder.

Refering to Figure 3, a view from above the SCGA Holder can be seen. Th.s consists of the Pads (it), The PCB (2) the Spring Clip (5) the Dust Seal (8) and the Position Locator (11). The Position Locator is used to prevent incorrect insertion of an IC into the SCGA Holder.

Other embodiments of this invention may be devised without departing from the scope or spirit of the present invention.

Claims

CLAllSIS

1) A new form of IC packaging as in Figures ! and 2.

2) A nenv way of PCB mounting of ICs as in Figures 2 and 3.

3) New Mounting techniques of ICs in either a socket or on surface mount assembly.

4 A Higher packaging density of pins per IC than conventional Dual In Line ICs 5) Low inductance connections via the Springs to a PCB.

6) A provision for heat sinkiny of ICs using the SCGA Holder.

7) A provision for a low insertion force when inserting an IC depending on the materials used for the Springs (3).

S) Vibration resistance.

9) A path for upgradability - The invention provides for a large number of IC pinouts.

10) Electro-magnetic shielding via the Dust Seal (8).

11) A device holder substantially as described herein with reference to figures 1, 2 and 3 of the accompanying drawings.