Note: Descriptions are shown in the official language in which they were submitted.
45~g
PHF. 81.607
The invention relates to a method by means of which an elec-
tronic circuit can be manufactured which is disposed in a support of
: an electrically insulating material and is protected by a screen from
electrostatic chargest the support being provided,at least locally
with electrically conducting surfaces which cover the electronic cir-
cuit and between which exists a preferential:path for an electric
current which suppresses the risk of an electric discharge by the elec-
tronic'circuit.
In a known method such as disclosed in:Canadian Patent Appli-
10 :cation S.N. 374,666 filed April 3, 1981 in the:name of Flonic S.A.(now:Canadian:Patent 1,I46,272), the metallizations of the metallized
surfaces of a synthetic material are interconnected through an elec-
tric connection of a kind not described in detail between the
metallizations.
m e invention:has for.its:object to provide a method of the
kind mentioned in the preamble W.hich is suitable for mass production
: and which requi'res only a ccmparatively small number of manufacturing
operations.
For this'puxposer the method according to the:in~ention is
characterized in that thr,ough-hole is'formed in the support and in
that foils of a thermoplastic'material, which are electrically conduc-
. ting or.are cover.d with a conducting:Iayer,.are arranged on:each sideof the support,. between.w,hi.ch foils is placed an electronic circuit
disposed in'a:cav,.ity o the support,. after which the:said foils are
pressed towards:each.other at the:area of the hole, while at the same
. time a quantity of heat:is'supplied,:'by means of which the thermoplas-
. tic material is':caused:to flow and is'pressed at least in:part into
. the holej after Rich the thermoplastic material is cooled underpressure in order that the~said'.preferential:path through solidified
30.. thermoplastic'material in'the hol,e:can:be maintainéd.
A special meth,od. in,'accord,ance w.ith the inv.ention., which
relates to the technology~of manu~actur'ing the support, is moreov.er
characterized in'that the support is':obtained by stacking sev,eral
. therm,oplastic'foils, at least a given number of which are prov,ided
with a first hole which is formed at the area of the.cavity of the
support and whose dimensions cor.respond to those of the said:cavity,
while these foils all are
,,~
- 12~45;29
Pi 81.607 2 03.11.1982
provided wlth a second hole which is formed at the area of the through-
hole of the support and whose dimensions correspond to those of the
through-hole, whereupon, after an electronic circuit has keen disposed
in -the cavity constitute by the said holes together, the support comr
posed of the stacked foils is covered on Roth sides with thermoplastic
foils covered with a conductive layer, after which all the foils are trans-
formed by pressure and supply of heat into a laminated structure.
A special method according to the invention, which is particularly
suitable for the manufacture of identification cards having electrical
contact regions which are accessible from the exterior, is moreover charac-
terized in that at least one of the foils which are electrically conducting
or are covered with a conducting layer, is provided with orifices which
are arranged opposite the electrical contact regions which are accessible
from the exterior, and in that the said contact regions are covered with
lS a mask, after which the quantity of heat is supplied to the thermoplastic
material, whereupon the mask is removed after the solidification of the
thermoplastic material.
In order that the invention may be readily carried into
effect, it will now be descriked more fully, by way of example, with
20 reference to the accompanying drawings, in which :
Figure 1 is a sectional view of a part of an identification
card according to the prior art,
Figure 2 is a sectional view of the same part of a card accor-
ding to the invention before the material has keen caused to flow,
Figure 3 is a sectional view of again the same part of a card
according to the invention in the finished state.
Figure 4 is a perspective view of an identification card.
Figure 4 represents a circle B limiting a part of a card.
This part is shown in a sectional view taken on the line A in Figure 1.
3~ Figure 1 shows the part comprising an integrated circuit in a
conventional embodiment of an identification card.
The electronic circuit comprises an integrated circuit chip
mounted in a small printea wiring circuit 14 of small thickness. The chip
is enclosed in the interior of this circuit at the level of the part of
35 excessive thickness 10.
This circuit 14 is included in a stack of foils 11 of polyvinyl
chloride designated as PVC, these foils being hot-pressed in order that
they are welded together to form a foiled block which forms a support 18 of
-
~Z~4529
P~-IF 81.G07 3 03.11.1982
small thickness mainly consisting of an insulating material, that is to
say the insulating material of the printed wiring circuit 14 and the in-
sulating material of the PVC foils 11. Orifices 16 formed in toe surface
foils 7 and 8 render accessible the contact regions carried by the cir-
cuit 14. prolongation 12 of reduced thickness of the circuit 14, whichprolongation is provided with holes 13, ensures that the printed wiring
circuit is anchored in the PVC material of the adjacent foils which pene-
trate into the holes 13, as is indicat~l in Figure 3, during the hot-
pressing process by means of which the foils are welded together. When
o such a stack of foils is used, there is a possibility of providing therein
cavities of a fairly complicated form if this is desired, by providing
first holes of a different form in each foil, which renders it possible
to adapt with accuracy the PVC block to the form of the eircuit 14.
The support 18 of Figure 1 does not comprise an electrostatic
screen. In order to provide it with such a screen, electrically conducting
surfaces are disposed at least locally on the faces of the said bcdy.
For example, conducting foils may ke disposed on the upper faces 21 and
the lower faces 22 of this bcdy. However, instead of subsequently pro-
viding such foils on a body 18 already treated, during the manufacture
of this bcdy surface foils, such as for example, the foils 1 and 8 or
the foils 2 and 7, may ye replaced by conducting foils. A thin conduc-ting
foil may also be interposed, for example, ketween the foils 1 and 2 on
the one hand and the foils 7 and 8 on the other hand.
The term "support" is to be understood to mean the part of the
^ ` 25 card constituted in this case by the foils 2 7 situated between the
conducting foils constituting the screen.
In order to interconnect electrically the conducting foils
each situated on a face of the bcdy, first at least one hole is formed in
the said bcdy. This hole having a size of akout 2 mm is shown at 15 in
Figure 2. In order to simplify the drawing, it is located beside the
printed wiring circuit 14, but it is clear that it may be located at any
area of the card. It is even advantageous to provide it at a fairly large
distance from the printed wiring circuit and especially at a fairly large
distance from any magnetic -tracks provided on the surface of the card in
35 order that the transfer of defonnations caused by the presence of this
hole during the hot-pressing process to these elements is limited to a
minimum.
Subsequently,the conducting surfaces are providecl in the form of a
~2~4529
PHF 81.607 4 03.11.1982
first foil 19 of a thermoplastic material, a conducting material or a
material coated with a conductive layer applied to a face of the said
kody, and of a second foil 20 of the same material applied to the other face
of the bcdy. The Applicant has used successfully foils of PVC having a
thickness of 35 em , which are aluminium-plated and are interposed ke-
tween the layers 1 and 2 on the one hand and ketween the layers 7 and 8
on the other hand. It is also possible to use foils of a thermoplastic
material which is rendered conducting due to a charge of conducting par-
ticles. In the em~cdiment shown, which shows only one possibility gong
many other possibilities,the PVC foils enumerated 1 to 8 have the follow-
ing respective thickness in microns :
foil 1 120 (together)
foil 2
foil 3
foil 4 580 (together)
foil 5
foil 6
foil 7 150 (together)
foil 8
Consequently, these foils constitute together with the two
foils of 35 em a stack having a thickness of 920 em which is reduced by
hot-pressing to 760 em whilst forming a laminated structure.
By the same pressing process, the foils 19 anl 20 are pressed one
towards the other whilst causing the thermoplastic material to flow, which
25 material is pressed into the hole 15. The PVC keing a thermoplastic
material, in practice the foils 1 and 19, just like the foils 20 and 8, a
given quantity of material of which flows horizontally during the flowing
process, together fill the hole 15. Figure 3 shows how these foils are
pressed towards the centre of the support and how parts of conducting sur-
30 faces of the foils 19 and 20 are displaced so that they come into contactwith each other along a surfae 17. Successfully used pressing conditions
are the following : PVC foil plates which are stacked and comprise a
plurality of supports arranged keside each other so that a plurality of
cards are formed in a single step are arranged between the heating plates
35 of a press. A pressure of 10 k~r is exerted for 25 seconds wi-thout
heating and then a heat treatment at 160 C is carried out for 7 minutes
at a pressure of 140 kar, after which the material is cooled for 6 minutes
at a pressure of 170 kar. Consequently this process essentially consists in
~2~SZ9
PliF S1.~07 5 03.11.1982
that for at least a given period of time a pressure is exerted and a tem-
perature increase is effected at the same time. These conditions of pres-
sure end temperature are otherwise the same as in the case of a PVC
card not provided with a screen and consequently are known to those skilled
in the art. The effect obtained in the case of the invention is fairly
s~lrprising because it could be exFected that all the foils participate in
the process of filling the hole 15 whilst not establishing electrical
connections between the foils 19 and 20.
The efect obtained shown in Figure 3 can be explained by the
fact that during the heat treatment the surface foils are first heated and
begin to flow before the internal foils have begun to soften sufficiently
to flow also. If otherwise a small quantity of material of these foils
should ke introduced at 17 ketween the conducting surfaces,this would
not have serious disadvantages kecause it is not necessary to have a free
ohmic connection at the level of the contact 17, it being essential
that the leakage path provided for an electrostatic charge is shorter at
this level than at the level of the electronic circuit 14 to be protected.
The second hole 15 is advantageously formed during the operation by
which the first hole for the printed wiring circuit 14 is formed, while
20 the hot-pressing process is the process by which the manufacture of the
cards according to the prior art is terminated; the method according to
the invention consec~lently does not introduce any additional manufacturing
operation and the obtained card is therefore very inexFensive.
As a result of the inhomogeneity due to the absence of a
25 thermoplastic material on the contact regions carried ky the electronic
circuit it is possible that the finished card is slightly inflected.
In order to avoid this, kefore causing the material to flow,
the said regions are locally covered with a mask 27 made of a material
different from that of thermoplastic foil 7, 8, whilst, after the material
30 has been caused to flow, the mask 27 covering the regions is removed.
The material of the mask has to be different from that forming
the foils in order that it can be removed selectively. It can advantageous-
ly be an ink applied by silk-screen printing on the printed wiring circuit
14 and removable by peeling. The thickness of the screening layer appliecl
35 by silk-screen printing is chosen so that the thickness of the mask is
such that it is at the level of the outer surface of the card after hot-
pressing. The Applicant utilizes successfully the ink designa-ed as SD 2951
of the society Werner Peters KG represented in France by the Société
5.29
PHF 81.607 6 03.11.1982
SUPRAT~X. The term "removable by peeling" is to be understood to mean that
this material, although it is fairly resistant for the protection of the
contacts during the manufacturing manipulations, is rendered non-adherent
by the thermal shock due to the hot-pressing process and can be very
readilly removed subsequently by peeling. According to the invention, a
novel application thereof is that it serves as a liner and prevents the
lateral displacement of the layers 7, 8 during pressing and flowing.
An identification card according to the invention consequently
comprises a support 18 of small thickness constituted in this exarnple by
the foils 2 to 7, in a first hole of which is disposed the printed wiring
`~; circuit 14 mainly of insulating material in which is ~eG4~ ten an inte-
grated circuit on the two surfaces 21, 22 of which are placed foils 19,20
which are conducting or covered with a conducting layer, these foils 19,
20 being made of thermoplastic material, the b^dy being provided with a
second hole 15 art the foils having a deformation which forms a part of
excessive thickness extending inwardly in the said hole together with
given parts of the conducting surfaces of the foils 19, 20 situated each
on opposed surfaces in contact with each other along a surface 17.
when the foils 19, 20 are made of a metallized thermoplastic
material, for exarnple, of alurninium-plated PVC, the alurninium does not
adhere to thc PVC of the adjacent foil. A solution, which after all is
:^ ver~7 satisfactory, consists in that it is smeared with a glue. However,
this constitutes a complication in the manufacture. Consequently,it is
preferable to realize the metallization through a stencil plate in order
2s that the metallization is perforated over the major part of the surface
of the foil. Thus, the PVC is caused to appear at numerous points of the
surface, as a result of which the foil can ye welded to the adjacent foil
during the hot-pressing process. It is also possible to perforate with a
punch the foils 19, 20 so that the foils 1 and 2 on the one hand and 7
arid 8 on the other hand are welded together through the perforations of
the foils 19, 20.
.
