Electrical connector for circuit boards

An electrical connector is provided which, when attached to a printed circuit board, will not cause removal of a cream solder that has been applied to the circuit board, and which will not flaw the surface of circuit portions. The connector has a resilient arm which undergoes elastic deformation to flex contacts perpendicularly away from the surface of the circuit portions when the circuit board is inserted into the connector. The resilient arm is restored to its original shape when the connector has been correctly fitted on the circuit board, thereby allowing the contacts to contact predetermined circuits. In another embodiment, the resilient arm is replaced by a frame member which is urged into the connector body by the circuit board. This causes the contacts to part perpendicularly from the surface of the circuit portions.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an electrical connector for circuit boards. 
2. Description of the Related Art 
electrical connectors for connecting the circuit on a circuit board with an 
external circuit are available in the art. One type of electrical 
connector for this purpose is fitted onto an edge portion of the circuit 
board to make contact with a connecting portion of the circuit. 
An example of such an electrical connector is illustrated in FIG. 5. The 
connector includes an insulating housing 51 from which two parallel rows 
of contacts 52 extend in cantilevered fashion. A circuit-board receiving 
groove 54 is formed in a projecting portion 53 located at both ends of the 
housing 51, and a portion of the circuit board receiving groove 54 has a 
key portion 55. The two rows of parallel contacts 52, one located above 
the other, include intermediate portions bent in such a manner that the 
opposing contacts in the two rows approach each other leaving a space 
between them which is smaller than the thickness of a circuit board P. 
The circuit board P has a row of connecting circuit portions P1 formed 
along one edge portion thereof. This edge portion is provided with guide 
grooves P3, one on each side of the row of connecting circuit portions Pl, 
which are guided by respective ones of the keys 55. 
When the connector is to be connected, a cream solder is sufficiently 
applied over an area S of the circuit portions P1 of circuit board P, 
after which the circuit board P is inserted between the upper and lower 
rows of the contacts 52 in such a manner that the guide grooves P2 mate 
with the keys 55 of the connector. As a result, the upper and lower 
contacts 52 make contact with the corresponding circuit portions P1. This 
is followed by heating the circuit portions P1 so that each contact is 
soldered and connected to the circuit on the circuit board P. 
The following problems arise in the electrical connector for circuit boards 
in the example of the prior art described above: 
(1) From the moment the contacts 52 start to contact the edge portion of 
the circuit board until the moment the connector has been fitted on the 
circuit board at the correct position, the contacts are in a sliding state 
relative to the circuit portions P1. As a consequence of such sliding, the 
cream solder is removed from the vital portions at which the contacts 52 
make contact with the circuit portions P1. 
(2) If the contacts 52 abut against the circuit portions P1 with a high 
pressure while sliding against the circuit portions P1 as described above, 
the surface of the contact portions P1 is scraped off. 
(3) In the process for fitting the connector onto the circuit board P, the 
pressure which one applies upon the other is constant and therefore it is 
not possible to tell when the connector has arrived at the correct fitting 
position. In addition, since there is an inclination between the two in 
the direction of connector width, there is no assurance that the fitting 
of the connector on the circuit board will be accomplished reliably. 
(4) The connector and the circuit board rely upon the keys 55 and guide 
grooves P3 for a proper fit. In order to achieve reliable positioning, the 
keys 55 and guide grooves P3 must be machined to a high precision. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a simply constructed 
electrical connector for a circuit board in which the cream solder can be 
retained on the circuit board reliably, and in which the surface of the 
circuit portions will not be damaged when the connector is fitted on the 
circuit board. 
In accordance with the present invention according to a first embodiment 
thereof, the foregoing object is attained by providing an electrical 
connector for being fitted on an edge portion of a circuit board and 
having contacts for coming into resilient pressured contact with circuit 
portions of the circuit board, the contacts and the circuit portions being 
soldered and connected together in a contacting state. The contacts extend 
from an insulating housing in cantilevered fashion and have distal ends 
supported by a resilient arm. The resilient arm has a projection which 
comes into abutting contact with the edge portion of the circuit board 
when the connector is fitted on the printed circuit board, and the 
resilient arm is elastically deformed by the abutting contact between the 
projection and the edge portion of the circuit board in such a manner that 
the contacts are spaced away from the surface of the circuit board. The 
projection mates with a locking recess of the circuit board, so that the 
resilient arm loses the elastically deformed state, when fitting of the 
connector on the circuit board at a correction position has been 
completed, whereby the contacts come into resilient pressured contact with 
the circuit portions. 
In use of the connector according to the first embodiment constructed as 
set forth above, the connector is fitted on the circuit board with the 
edge portion of the circuit board being brought into abutting contact with 
the projection. 
When the projection abuts against the edge portion of the circuit board, 
the resilient arm is elastically deformed so that the contacts, whose 
distal ends are being supported by the resilient arm, also are elastically 
deformed so as to be spaced away from the surface of the circuit board. 
The connector is thus fitted on the circuit board at the correct position 
in a state where the contacts are not in contact with the circuit board. 
When this correct position is attained, the projection on the resilient 
arm snaps into engagement with the locking recess of the circuit board, as 
a result of which the arm is restored to its original shape. This allows 
the contacts to perpendicularly contact the surface of the circuit 
portions for the first time. 
Finally, the contacts and circuit portions are heated to solder and connect 
the two together by means of a cream solder applied to the circuit 
portions in advance. 
In accordance with the present invention according to a second embodiment 
thereof, the foregoing object is attained by providing an electrical 
connector for being fitted on an edge portion of a circuit board and 
having contacts for coming into resilient pressured contact with circuit 
portions provided on the edge portion of the circuit board, the contacts 
and the circuit portions being soldered and connected together in a 
contacting state. The contacts are implanted in an insulating housing in a 
cantilevered state and each has an intermediate portion formed to include 
a horizontal portion extending in a direction in which the connector is 
fitted on the circuit board. The insulating housing guides and retains an 
insulating frame member movable relative to the insulating housing in the 
direction in which the connector is fitted on the circuit board. The frame 
member has locking portions which, when the frame member is fitted into 
the insulating housing, engage the horizontal portions of the contacts and 
elastically deform the contacts in a direction which spaces the contacts 
away from the surface of the circuit portions of the circuit board; an 
insertion portion into which the edge portion of the circuit board is 
urged; and projections which, when the edge portion of the circuit board 
in urged into the insertion portion, mate with locking recesses formed in 
the edge portion of the circuit board. After the circuit board is engaged 
with the frame member by urging the circuit board into the frame member, 
the frame member is moved together with the circuit board into the 
insulating housing up to a position at which the connector is correctly 
fitted on the circuit board, as a result of which the locking portions of 
the frame member part from the horizontal portions of the contacts, 
whereby the contacts come into resilient pressured contact with the 
circuit portions of the circuit board. 
According to the second embodiment of the invention constructed as set 
forth above, the circuit board and the connector are connected through the 
following procedure. 
First, the frame member is fitted into the insulating housing. As a result, 
the horizontal portions of the contacts engage the locking portions of the 
frame member, whereby the contacts are caused to part from the surface of 
the circuit board when the connector is fitted on the circuit board. In a 
modification, it is permissible for the frame member to be incorporated 
from the start as one member of the insulating housing. 
Next, the edge portion of the circuit board is pressed into the insertion 
recess of the frame member. When this is done, the projection of the frame 
member mates with the locking recess of the circuit board. As a result, 
the circuit board is brought to the correct position in the transverse 
direction and moves in unison with the frame member. 
When the circuit board is pressed in further, the accompanying frame member 
is moved into the insulating housing and stops when the connector assumes 
a position at which it is correctly and completed fitted on the circuit 
board. In addition, since the locking portions of the frame member are 
spaced away from the area of the horizontal portions of the contacts owing 
to this movement, the contacts come into resilient pressured contact with 
the circuit portions of the circuit board in a direction at right angles 
to the surface of these portions. 
Finally, the contacts and circuit portions are heated to solder and connect 
the two together by means of a cream solder applied to the circuit 
portions in advance. 
Other features and advantages of the present invention will be apparent 
from the following description taken in conjunction with the accompanying 
drawings, in which like reference characters designate the same or similar 
parts throughout the figures thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A first embodiment of the present invention will now be described with 
reference to FIG. 1 and FIGS. 2A through 2C. 
As shown in FIG. 1, numeral 1 denotes a first embodiment of an electrical 
connector to be fitted on a circuit board P. The circuit board P has an 
edge portion on which circuit portions P1 for connecting purposes are 
formed, and is provided with locking holes P2, one on each side of the row 
of circuit portions P1. 
The connector 1 includes an insulating housing 2 on which a plurality of 
contacts 3 arranged in two parallel rows, one above the other, are held in 
cantilevered fashion. The two parallel rows of contacts 3 are bent at 
their intermediate portions in such a manner that opposing contacts 
approach each other, with the spacing between the opposing contacts being 
smaller than the thickness of the circuit board P. 
The contacts 3 face a connector-receiving recess (not shown) formed in a 
rear portion of the insulating housing 2 and are adapted to contact the 
corresponding contacts of a mating connector C [see FIG. 2(A)]inserted 
into the above-mentioned connector-receiving recess. 
The insulating housing 2 is provided with two resilient arms 4 arranged one 
above the other in symmetrical fashion. The arms 4 project from both sides 
of the upper and lower rows of contacts 3 and extend in the same direction 
as the contacts 3, the distal ends of the arms being connected by 
connecting portions 5. The upper and lower resilient arms 4 together 
support the distal ends of the upper and lower contacts 3 from their inner 
sides. 
The opposing inner surfaces of the resilient arms 4 are provided with 
projections which engage with the locking holes P2 of the circuit board P. 
The procedure for fitting the electrical connector of the first embodiment 
on the circuit board P will now be described. 
(1) First, before the connector is attached, a cream solder W is applied 
over an area S (see FIG. 1) of the circuit portions P1 of circuit board P. 
This is shown in FIG. 2(A). 
(2) Next, the connector 1 is fitted on the circuit board P from the edge 
portion thereof provided with the circuit portions P1. At this time, the 
projections 6 provided on the upper and lower resilient arms 4 of the 
connector come into abutting contact with the edge portion of the circuit 
board P, as a result of which the upper and lower resilient arms 4 are 
spread apart owing to elastic deformation [see FIG. 2(B)]. As a result, 
the bent intermediate portions of the upper and lower contacts 3 are 
elastically deformed so as to be spaced away from the top and bottom 
surfaces of the circuit board P. 
(3) The circuit board P thus receives the connector 1 at a correct position 
where the contacts 3 are not in contact with the board. At this position, 
as shown in FIG. 2(C), the projections 6 of the resilient arms 4 engage 
with the corresponding locking holes P2, whereby the arms 4 are maintained 
at this position and return simultaneously to their normal state in which 
they are no longer elastically deformed i.e., no longer deflected away 
fromthe board. As a result, the contacts 3 come into resilient pressured 
contact with the circuit portions P1 of circuit board P at right angles to 
the surface of the circuit portions. 
(4) Finally, the cream solder at the portions of contact between the 
contacts 3 and the circuit portions P1 is heated to solder and connect the 
contacts to the circuit portions. 
In this embodiment of the invention, both the contacts and the resilient 
arms supporting them are provided above and below the circuit board. 
However, it is of course permissible to provide the contacts and the 
resilient arms on only one side of the circuit board. 
Further, the resilient arms need not be formed integral with the insulating 
housing, as illustrated. It is permissible to form the resilient arms 
separately of the housing and then combine them with the housing. 
Furthermore, if the portion of each resilient arm which supports the 
contacts is formed to have a groove for retaining each contact at a 
prescribed position, then the contacts can be positioned more accurately 
in the direction of connector width and the contact positions can be 
stabilized to be precisely aligned on the circuit portions of the board. 
The present invention as illustrated in this embodiment as described above 
is so adopted that the contacts do not contact the circuit portions of the 
circuit board until the connector and circuit board assume correct 
positions when fitted together. When the circuit board and connector are 
correctly fitted together, contact at such time is achieved at right 
angles to the surface of the circuit portions. Therefore, when the 
connector is attached, the cream solder on the circuit portions is not 
removed but is maintained intact from the beginning in reliable fashion. 
Furthermore, since the contacts do not slide on the circuit portions, the 
surface of each circuit portion is not flawed and therefore the 
reliability of connection is improved. 
A second embodiment of the present invention will now be described with 
reference to FIG. 3 and FIGS. 4(A) through 4(C). 
A shown in FIG. 3, numeral 11 denotes a second embodiment of an electrical 
connector to be fitted on the circuit board P. The circuit board P is the 
same as that used in the first embodiment shown in FIG. 1, and therefore 
identical portions are designated by like reference characters and need 
not be described again. 
As in the first embodiment, the electrical connector 11 includes an 
insulating housing 12 on which a plurality of contacts 13 arranged in two 
parallel rows, one above the other, are held in cantilevered fashion. The 
two parallel rows of contacts 13 ar bent at their intermediate potions in 
such a manner that opposing contacts approach each other, with the spacing 
between most-constricted portions 13a of the opposing contacts being 
somewhat smaller than the thickness of the circuit board P. these 
structural features are similar to those of the first embodiment. In this 
embodiment, the intermediate portion of each contact 13 is formed to have 
a horizontal portion 13b at a position offset toward the base end of the 
contact from the most-constricted portion 13A. 
As in the first embodiment, the contacts 13 face a connector-receiving 
recess (not shown) formed in a rear portion of the insulating housing 12 
and are adapted to contact the corresponding contacts of a mating 
connector C [see FIG. 4(A)] inserted into the above-mentioned 
connector-receiving recess. 
A frame member 14 is coporated in the simulating housing 12 of this 
embodiment. The frame member 14 has a pair of upper and lower resilient 
arms 14A provided on on two opposing sides thereof and extending 
longitudinally of the contacts 13, and a connecting portion 14b connecting 
the base ends of the pair of resilient arms 14A at the two opposing sides 
of the frame member 14. The upper and lower resilient arms 14A have distal 
ends whose mutually opposing surfaces are provided with projections 14C. 
When the circuit board P is inserted between the upper and lower resilient 
arms 14A, the projections 14C mate with the locking holes P2 of the 
circuit board P to effect positioning in the transverse direction (i.e., 
the direction along the edge of the circuit board) and lock the frame 
member 14 relative to the circuit board P by joining the two together. The 
base end of each resilient arm 14A is formed to have block-shaped guided 
portion 14D adapted to be guided and held by projecting guide portions 12A 
of the housing 12. 
The connecting portion 14B of the frame member 14 has upper and lower 
surfaces provided with guide grooves 14E serving as locking portions which 
receive the corresponding horizontal portions 13B of the contacts 13. The 
guide grooves 14E are set in such a manner that the distance between the 
bottom surfaces of the upper and lower guide grooves is somewhat larger 
than the thickness of the circuit board P at the circuit portions P1. 
The procedure for fitting the electrical connector of the second embodiment 
on the circuit board P will now be described. 
(1) First, before the connector is attached, a cream solder W is applied 
over an area S (see FIG. 3) of the circuit portions P1 of circuit board P. 
This is shown in FIG. 4(A). 
(2) Next, the frame member 14 is mounted within the insulating housing 12 
and is retained in guidable fashion. In this state the horizontal portions 
13B of the contacts 13 slidably engage with the guide grooves 14E serving 
as the locking portions of the frame member 14. As a result, the contacts 
13 elastically deform in a direction which spaces them away from the 
surface of the circuit on the circuit board P [see FIG. 4(A)]. 
(3) Thereafter, the circuit board P is pressed into the frame member 14 
from the edge thereof provided with the circuit portions P1. When this is 
done, the projections 14C provided on the upper and lower resilient arms 
14A of the frame member 14 come into abutting contact with the circuit 
board P, as a result of which the upper and lower resilient arms 14A are 
elastically deformed and spread apart. As the circuit board P is pressed 
in further, the projections 14C snap into engagement with the locking 
holes P2 of the circuit board P [see FIG. 4(B)]. Thus, the circuit board P 
and frame member 14 are joined together. At this time the circuit board P 
is automatically positioned in the transverse direction by the mating of 
the projections 14C with the holes P2. 
(4) When the circuit board P is pressed in still further, the frame member 
14 joined to it moves a predetermined distance into the insulating housing 
12 until it abuts against a stopper (not shown). During this movement, the 
guide grooves 14E of the frame member 14 come into contact with the 
horizontal portions 13B of the contacts 13 and the contacts 13 remain out 
of contact with the surface of the circuit portions as before. Then, when 
the frame member 14 has completely traversed the predetermined distance, 
the horizontal portions 13B part from the guide grooves 14E serving as the 
locking portions, and the contacts 13 come into resilient pressured 
contact with the circuit portions P1 from a direction at right angles 
thereto [see FIG. 4(C)]. 
(5) Finally, the cream solder at the portions of contact between the 
contacts 13 and the circuit portions P1 is heated to solder and connect 
the contacts to the circuit portions. 
In accordance with the second embodiment of the invention, the contacts, 
the resilient arms of the frame member which support the contacts, and the 
locking portions are provided above and below the circuit board. However, 
it is of course permissible to provide these elements on only one side of 
the circuit board. 
In this embodiment, the locking portions of the frame member are formed as 
guide grooves in the preferred example in order to improve the accuracy of 
guiding and positioning. However, the frame member may be formed merely to 
have a planar surface for elastically deforming the horizontal portions of 
the contacts. 
According to the present invention as illustrated in the second embodiment 
as described above, the arrangement is such that the contacts do not 
contact the circuit portions of the circuit board until the connector and 
circuit board assume correct positions when fitted together. When the 
circuit board and connector are correctly fitted together, contact at such 
time is achieved at right angles to the surface of the circuit portions. 
Therefore, when the connector is attached, the cream solder on the circuit 
portions is not removed but is maintained intact from the beginning. 
Soldering can be performed even more reliably than in the first 
embodiment. Furthermore, since the contacts do not slide on the circuit 
portions, the surface of each circuit portion is not flawed and therefore 
the reliability of connection is improved. 
As many widely different embodiments of the present invention can be made 
without departing from the spirit and scope thereof, it is to be 
understood that the invention is not limited to the specific embodiments 
thereof except as defined in the appended claims.