Patent Description:
Among connectors for mediating high-speed transmission of signals between a circuit board and an expansion board, there is a type of connector in which the connector mounted on the circuit board side is a socket type, the connector mounted on the expansion board side is a plug type, and the terminals of both connectors are electrically connected by fitting the plug type connector to the frontage of the socket type connector. As an example, this type of connector is called mezzanine connector.

As an example of documents disclosing a technique related to this type of connector, <CIT> (hereinafter referred to as "Patent Document <NUM>") can be taken up. The connector described in this document has a box-shaped housing and contacts arranged side by side on its wall surface. The bottom surface of the housing of this connector is provided with a boss inserted into a positioning hole in a circuit board, and contacts are provided at the frontage on the side opposite to the side with the boss in the housing. The reflow mounting of this type of connector on a board is performed by placing the connector at a predetermined position on the board with the cap attached, raising the temperature from ordinary temperature to about <NUM> degrees to melt the solder, and returning it to ordinary temperature.

The problem with this type of mezzanine connector is that when the difference between the thermal expansion coefficient of the material of the circuit board on which the socket type connector is mounted, and the thermal expansion coefficient of the material of the circuit board on which the plug type connector is mounted is large, mounting position deviation of the socket type connector and the plug type connector becomes larger after reflow.

The present disclosure has been made in view of such a problem, and one of the objects is to absorb the difference between the thermal expansion coefficient of the material of the circuit board on which the socket type connector is mounted and the thermal expansion coefficient of the material of the circuit board on which the plug type connector is mounted, and reduce the mounting position error. Patent document <CIT> discloses a connector set including at least one of a header and a socket and a jointer. The jointer extends in a direction and is configured to couple the header and the socket so as to be in parallel with each other. The jointer includes first jointer connecting portions provided at both end portions thereof and extending in a second direction perpendicular to the first direction, and which are configured to engage first connecting portions provided at both end portions of the header, and second jointer connecting portions provided at both end portions of the jointer body and extending in a third direction opposite to the second direction, and which are configured to engage the second connecting portions provided at both end portions of the socket.

The invention corresponds to the connector set as disclosed in claim <NUM>.

Accordingly, there is provided a connector set including: a first connector; a first cap to be attached to the first connector when the first connector is reflow-mounted on a first external substrate; a second connector; and a second cap to be attached to the second connector when the second connector is reflow-mounted on a second external substrate formed of a material with a smaller thermal expansion coefficient than that of the first external substrate, wherein the second cap is formed of a material with a smaller thermal expansion coefficient than that of the first cap.

The first connector includes a first housing with a slot and a plurality of contacts arranged in the slot, the second connector includes a second housing with a header to be fitted in the slot. The first connector is arranged in a direction orthogonal to an extending direction of the slot and held by the first cap, and the second connector is arranged in a direction orthogonal to an extending direction of the header and held by the second cap.

Further, the relation of the ratio α11/α10 of a thermal expansion coefficient α11 to a thermal expansion coefficient α10 and the ratio α21/α20 of the thermal expansion coefficient α21 to a thermal expansion coefficient α20 may be α11/α10 ≈ α21/α20, here the thermal expansion coefficient α11 is the thermal expansion coefficient of the first cap in an arrangement direction of the first connector, the thermal expansion coefficient α10 is the thermal expansion coefficient of the first external substrate, the thermal expansion coefficient α21 is the thermal expansion coefficient of the second cap in an arrangement direction of the second connector, and the thermal expansion coefficient α20 is the thermal expansion coefficient of the second external substrate.

Further, the number of the slots in one first connector may be two, and the number of the headers in one second connector may be two.

Further, among the contacts respectively disposed on both sides of the slots and the headers, the position of the contact on one side and the position of the contact on the other side may be shifted by <NUM>/<NUM> contact.

Further, the first housing and the second housing may have a rotationally asymmetrical shape as viewed from the fitting direction.

Further, the first housing may include a bottom portion, first wall portions facing each other in a first direction orthogonal to the fitting direction, and second wall portions facing each other in a second direction orthogonal to the fitting direction and the first direction, so as to surround the slot. The slot may be separated into a plurality of slots by a partition wall extending along the first direction, one end portion of the partition wall may be connected to one first wall portion of the two first wall portions on both sides of the first direction, the other end portion of the partition wall may be not connected to the other first wall portion. A gap may be formed between the other end portion of the partition wall and the other first wall portion. The second housing may include a plurality of headers. The plurality of headers may extend in the first direction, and a fitting plate portion to be fitted in the gap may be provided between the adjacent one end portions of the plurality of headers in the first direction.

In accordance with a second embodiment, there is provided a connector set including: a first connector; a first cap to be attached to the first connector when the first connector is reflow-mounted on a first external substrate; a second connector; and a second cap to be attached to the second connector when the second connector is reflow-mounted on a second external substrate formed of a material with a smaller thermal expansion coefficient than that of the first external substrate, the first cap and the second cap are formed of different materials in such a manner that a mounting position error is less than <NUM> when the first cap is reflow-mounted on the first external substrate and the second cap is reflow-mounted on the second external substrate.

In accordance with a third embodiment, there is provided a cap including: a first cap to be attached to a first connector when the first connector is reflow-mounted on a first external substrate; a second connector; and a second cap to be attached to the second connector when the second connector is reflow-mounted on a second external substrate formed of a material with a smaller thermal expansion coefficient than that of the first external substrate, wherein the second cap is formed of a material with a smaller thermal expansion coefficient than that of the first cap.

Here, the relation of the ratio α11/α10 of the thermal expansion coefficient α11 to the thermal expansion coefficient α10 and the ratio α21/α20 of the thermal expansion coefficient α21 to the thermal expansion coefficient α20 may be α11/α10 ≈ α21/α20, here the thermal expansion coefficient α11 is the thermal expansion coefficient of the first cap in an arrangement direction of the first connector, the thermal expansion coefficient α10 is the thermal expansion coefficient of the first external substrate, the thermal expansion coefficient α21 is the thermal expansion coefficient of the second cap in an arrangement direction of the second connector, and the thermal expansion coefficient α20 is the thermal expansion coefficient of the second external substrate.

Hereafter, a socket type connector <NUM>, a plug type connector <NUM>, a first cap <NUM>, and a second cap <NUM> that form a connector set according to one embodiment of the present disclosure will be explained with reference to drawings. A plurality of (four in the example of <FIG>) socket type connectors <NUM> and plug type connectors <NUM> are arranged side by side, and are respectively mounted on a first substrate <NUM> and a second substrate <NUM>. The second substrate <NUM> is formed of a material with a lower thermal expansion coefficient than that of the first substrate <NUM>. For example, the material of the first substrate <NUM> is FR4 (Flame Retardant Type <NUM>), and the material of the second substrate <NUM> is ceramic.

When headers <NUM> of the plug type connectors <NUM> on the second substrate <NUM> are fitted into slots <NUM> of the socket type connectors <NUM> on the first substrate <NUM>, the contacts <NUM> of the socket type connectors <NUM> are electronically connected to the contacts <NUM> of the plug type connector <NUM>, and high speed differential transmission based on PAM (Pulse Amplitude Modulation) becomes possible.

The first cap <NUM> is attached to the socket type connectors <NUM> when the socket type connectors <NUM> are reflow-mounted on the first substrate <NUM>. The second cap <NUM> is attached to the plug type connectors <NUM> when the plug type connectors <NUM> are reflow-mounted on the second substrate <NUM>.

In the following description, the fitting direction of the plug type connector <NUM> to the socket type connector <NUM> is appropriately referred to as the Z direction, the direction orthogonal to the Z direction is appropriately referred to as the X direction, and the direction orthogonal to the Z direction and the X direction is appropriately referred to as the Y direction. In addition, the +Z side may be referred to as an upper side, the -Z side may be referred to as a lower side, the +X side may be referred to as a front side, the -X side may be referred to as a rear side, the +Y side may be referred to as a left side, and the -Y side may be referred to as a right side.

As shown in <FIG>, the socket type connector <NUM> has a first housing <NUM>, solder tab terminals <NUM> and contacts <NUM>. As shown in <FIG>, the plug type connector <NUM> has a second housing <NUM>, solder tab terminals <NUM> and contacts <NUM>. The first housing <NUM> of the socket type connector <NUM> and the second housing <NUM> of the plug type connector <NUM> are formed by injecting resin in the X direction which is the longitudinal direction. The first housing <NUM> of the socket type connector <NUM> and the second housing <NUM> of the plug type connector <NUM> have a rotationally asymmetrical shape. In the present disclosure, the socket type connector <NUM> corresponds to, for example, the first connector defined in claims and the plug type connector <NUM> corresponds to, for example, the second connector defined in claims.

More specifically, the first housing <NUM> of the socket type connector <NUM> is provided with two slots <NUM>. The two slots <NUM> extend in the X direction. The first housing <NUM> has a bottom portion <NUM> that becomes the bottom of the housing <NUM>, wall portions <NUM> and wall portions <NUM> respectively facing each other in the X direction and the Y direction so as to surround the slots <NUM>, and a partition wall <NUM> separating the two slots <NUM> in a frontage surrounded by the wall portions <NUM> and the wall portions <NUM>. The wall portions <NUM> extend in the Y direction, and the wall portions <NUM> extend in the X direction. In the present disclosure, the wall portions <NUM> and the wall portions <NUM> correspond to, for example, the first wall portions and the second wall portions that are defined in claims, respectively.

The end portion of the partition wall <NUM> on the -X side is connected to the wall portion <NUM> on the -X side. The end portion of the partition wall <NUM> on the +X side is not connected to the wall portion <NUM> on the +X side, and a gap <NUM> is formed between the end portion of the partition wall <NUM> on the +X side and the wall portion <NUM> on the +X side.

A round hole <NUM> is provided in the middle of the wall portion <NUM> on the -X side in the Y direction. A long hole <NUM> is provided in the middle of the wall portion <NUM> on the +X side in the Y direction. The +X side of the long hole <NUM> is open. Rectangular grooves <NUM> are provided on the +Y side and the -Y side of the holes in the wall portion <NUM> on the -X side and the wall portion <NUM> on the +X side. The rectangular grooves <NUM> are recessed from the upper surfaces of the wall portions <NUM> toward the bottom portion <NUM>. Holes are perforated at the bottoms of the rectangular grooves <NUM>, and the solder tab terminals <NUM> are fitted and fixed in the holes. As shown in <FIG>, the solder tab terminal <NUM> has an elongated substrate portion <NUM> and two projecting piece portions <NUM> rising from two end portions of one long side of the substrate portion <NUM>. The two projecting piece portions <NUM> are fitted into the holes at the bottom of the rectangular groove <NUM> of the first housing <NUM>.

As shown in <FIG>, on the lower sides of the inner surfaces of the wall portions <NUM> on the +X side and the -X side on the slots <NUM> sides, there are engaging pieces <NUM> projecting to the slots <NUM> sides.

Grooves <NUM> are provided in the inner surfaces of the wall portions <NUM> and the side surfaces of the partition wall <NUM>. Contacts <NUM> are accommodated in the grooves <NUM>. As shown in <FIG>, the contact <NUM> has a linear portion <NUM> extending in one direction, a terminal portion <NUM> at one end of the linear portion <NUM>, and a fork portion <NUM> at the other end of the linear portion <NUM>. The terminal portion <NUM> is bent into a doglegged shape. The fork portion <NUM> is bifurcated. Solder <NUM> is caulked and fixed to the fork portion <NUM>. The contact <NUM> is held in the grooves <NUM> of the wall portion <NUM> and the partition wall <NUM>, and the fork portion <NUM> of the contact <NUM> and the solder <NUM> are exposed to the opposite side to the groove <NUM> side through the hole in the bottom portion <NUM>.

As shown in <FIG> and <FIG>, the first cap <NUM> has a box shape with a width in the X direction and the Y direction slightly larger than that of four socket type connectors <NUM> arranged side by side. A first opening <NUM> for accommodating and holding the socket type connectors <NUM> is provided on the -Z side of the first cap <NUM>. The first cap <NUM> has a top plate portion <NUM> that constitutes a ceiling of the first cap <NUM>, wall portions <NUM> and wall portions <NUM> respectively facing each other in the X direction and the Y direction across the first opening <NUM>.

A hooking spring <NUM> and a spring accommodation portion <NUM> are provided at a position corresponding to each slot <NUM> of four first housings <NUM> inside the wall portion <NUM> on the -X side and the wall portion <NUM> on the +X side. As shown in <FIG>, the lower end portion <NUM> of the hooking spring <NUM> projects outward in a triangular shape.

A positioning pin is provided at a position corresponding to the round hole <NUM> between the adjacent spring accommodation portions <NUM> inside the wall portion <NUM> on the -X side. The positioning pin has a shape to be put in the round hole <NUM>. A positioning long pin is provided at a position corresponding to the long hole <NUM> between the adjacent spring accommodation portions <NUM> inside the wall portion <NUM> on the +X side. The positioning long pin has a shape to be put in the long hole <NUM>.

The attachment of the first cap <NUM> to the socket type connector <NUM> and the reflow mounting thereof are performed as follows. First, the four socket type connectors <NUM> are arranged so that the orientation of the gaps <NUM> of a part of the socket type connectors <NUM> and the orientation of the gaps <NUM> of the remaining socket type connectors <NUM> are reversed (for example, the gaps <NUM> of two socket type connectors <NUM> in the middle are on the -X side, and the gaps <NUM> of two socket type connectors <NUM> at both ends are on the +X side).

Next, the first cap <NUM> is attached to the four socket type connectors <NUM> so that the positioning pins are inserted into the round holes <NUM> on the -X side, the positioning long pins are inserted into the long holes <NUM> on the +X side, and the hooking springs <NUM> are fitted inside the wall portions <NUM> on the -X side and the +X side. As shown in Fig. 14A and Fig. 14B, when the first cap <NUM> is attached to the four socket type connectors <NUM>, the lower end portions <NUM> of the hooking springs <NUM> of the first cap <NUM> engage with the engaging pieces <NUM> of the connectors <NUM>, and the socket type connectors <NUM> are supported from the inside in the X direction by the hooking springs <NUM> of the first cap <NUM>.

Next, the four socket type connectors <NUM> gathered by the first cap <NUM> are placed on a predetermined position of the first substrate <NUM>, and are put into a reflow device. The temperature in the device is changed from <NUM> to <NUM> to <NUM>. When the temperature exceeds <NUM>, the solder <NUM> at the tip end portion of the contact <NUM> is melted, and when the temperature returns to ordinary temperature, the solder <NUM> solidifies. The contact <NUM> of the socket type connector <NUM> and the pad of the first substrate <NUM> are connected to each other by the solidification of the solder <NUM>. After the socket type connector <NUM> is attached to the first substrate <NUM>, the first cap <NUM> is removed from the socket type connector <NUM>.

As shown in <FIG> and <FIG>, the second housing <NUM> of the plug type connector <NUM> is provided with two headers <NUM>. The two headers <NUM> extend in the X direction. The end portions on the -X side, +X side, -Y side, and +Y side of the bottom portion <NUM> that becomes the bottom of the two headers <NUM> of the second housing <NUM> project outside the portion that supports the headers <NUM>. A fitting plate portion <NUM> is provided between the end portions of two adjacent headers <NUM> on the -X side in the second housing <NUM>.

A round hole <NUM> is provided in the middle of the end portion of the bottom portion <NUM> on the -X side in the Y direction. A second long hole is provided in the middle of the end portion of the bottom portion <NUM> on the +X side in the Y direction. The +X side of the second long hole is open. Rectangular holes <NUM> are provided on the +Y side and the -Y side of the holes in the end portions of the bottom portion <NUM> on the -X side and the +X side. Solder tab terminals <NUM> are fitted and fixed in the rectangular holes <NUM>.

Grooves <NUM> are provided in the side surfaces of the two headers <NUM> on the +Y side and the -Y side. Contacts <NUM> are accommodated in the grooves <NUM>. The contacts <NUM> are held in the grooves <NUM> of the headers <NUM>, and the fork portions <NUM> of the contacts <NUM> and solder <NUM> are exposed on the opposite side to the grooves <NUM> side through holes in the bottom portion <NUM>.

As shown in <FIG> and <FIG>, the second cap <NUM> has a box shape with a width in the X direction and the Y direction slightly larger than that of four plug type connectors <NUM> arranged side by side. A second opening <NUM> for accommodating and holding the plug type connectors <NUM> is provided on the +Z side of the second cap <NUM>. The second cap <NUM> has a top plate portion <NUM> that becomes a ceiling of the second cap <NUM>, wall portions <NUM> and wall portions <NUM> respectively facing each other in the X direction and the Y direction across the second opening <NUM>.

There are holding piece portions <NUM>,which project inside, at positions corresponding to the gaps between the headers <NUM> of the second housings <NUM> on the inner side of the wall portion <NUM> on the -X side. There are holding piece portions <NUM>,which project inside, at positions corresponding to the gaps between the headers <NUM> of the second housings <NUM> on the inner side of the wall portion <NUM> on the + X side.

Positioning pins are provided at positions corresponding to the round holes <NUM> of the second housings <NUM> between the adjacent holding piece portions <NUM> of the wall portion <NUM> on the -X side. The positioning pin has a shape to be put in the round hole <NUM>. Positioning long pins are provided at positions corresponding to the second long holes of the second housings <NUM> between the adjacent holding piece portions <NUM> of the wall portion <NUM> on the +X side. The positioning long pin has a shape to be put in the second long hole.

The attachment of the second cap <NUM> to the plug type connectors <NUM> and the reflow-mounting thereof are performed as follows. First, the four plug type connectors <NUM> are arranged so that the combination of the fitting plate portions <NUM> on one side and the fitting plate portions <NUM> on the other side fits the gap of the four socket type connectors <NUM>.

Next, the second cap <NUM> is attached to the four plug type connectors <NUM> so that the positioning pins are inserted into the round holes <NUM> on the +X side and the positioning long pins are inserted into the second long holes on the -X side. When the second cap <NUM> is attached to the four plug type connectors <NUM>, the holding piece portions 227and <NUM> of the second cap <NUM> abut against the headers <NUM> of the plug type connectors <NUM>, and the four socket type connectors <NUM> are supported from the outside in the X direction by the holding piece portions 227and <NUM> of the second cap <NUM>.

Next, the four plug type connectors <NUM> gathered by the second cap <NUM> are placed on a predetermined position of the second substrate <NUM>, and are put into a reflow device. The temperature in the device is changed from <NUM> to <NUM> to <NUM>. When the temperature exceeds <NUM>, the solder <NUM> at the tip end portion of the contact <NUM> is melted, and when the temperature returns to ordinary temperature, the solder <NUM> solidifies. The contact <NUM> of the plug type connector <NUM> and the pad of the second substrate <NUM> are connected to each other by the solidification of the solder <NUM>. After the plug type connector <NUM> is attached to the second substrate <NUM>, the second cap <NUM> is removed from the plug type connector <NUM>.

When the plug type connector <NUM> and the socket type connector <NUM> are connected in a correct orientation, the fitting plate portion <NUM> of the plug type connector <NUM> is fitted to the gap <NUM> of the socket type connector <NUM>. When the plug type connector <NUM> and the socket type connector <NUM> are connected in an incorrect orientation, the fitting plate portion <NUM> of the plug type connector <NUM> interferes with the partition wall <NUM> of the socket type connector <NUM>. When the plug type connector <NUM> and the socket type connector <NUM> are oriented in opposite directions, the fitting plate portion <NUM> and the partition wall <NUM> interfere with each other, so that reverse insertion of plug type connector <NUM> and the socket type connector <NUM> is prevented.

As shown in <FIG>, when the plug type connector <NUM> and the socket type connector <NUM> are connected in the correct orientation, the contacts <NUM> of the plug type connector <NUM> and the contacts <NUM> of the socket type connector <NUM> come into contact with each other. Further, as shown in <FIG>, among the contacts <NUM> disposed oppositely on both sides of each of the header <NUM> and the slot <NUM>, the position of the contact on the -Y side and the position of the contact <NUM> on the +Y side are shifted in the X direction by <NUM>/<NUM> contact. The reason why the position of the contact <NUM> on the -Y side and the position of the contact <NUM> on the +Y side are shifted in the X direction by <NUM>/<NUM> contact is to effectively prevent crosstalk.

Here, the first cap <NUM> and the second cap <NUM> are formed of different materials. The thermal expansion coefficient of the material of the second cap <NUM> is smaller than the thermal expansion coefficient of the material of the first cap <NUM>. More specifically, when the thermal expansion coefficient of the first cap <NUM> in the Y direction, which is the arranging direction of the four socket type connectors <NUM>, is α11, the thermal expansion coefficient of the first substrate <NUM> in the Y direction is α10, the thermal expansion coefficient of the second cap <NUM> in the Y direction is α21, and the thermal expansion coefficient of the second substrate <NUM> in the Y direction is α20, α11/α10≈α21/α20. This is to settle the difference between the mounting position of the contact <NUM> of the socket type connector <NUM> on the first substrate <NUM> and the mounting position of the contact <NUM> of the plug type connector <NUM> on the second substrate <NUM> to be less than <NUM>.

The reason why the mounting position error of the socket type connector <NUM> and the plug type connector <NUM> can be reduced by setting the thermal expansion coefficient of the second cap <NUM> smaller than the thermal expansion coefficient of the first cap <NUM> is as follows.

As shown in <FIG>((A) and (B-<NUM>)), in the reflow mounting, the first cap <NUM>, the first housing <NUM>, and the first substrate <NUM>, as well as the second cap <NUM>, the second housing <NUM>, and the second substrate <NUM> expand in the Y direction when the temperature in the reflow device becomes high, and contract when the temperature returns to ordinary temperature.

With the expansion of the first cap <NUM>, the distance between the adjacent contacts <NUM> in the first housing <NUM> of the socket type connector <NUM> widens, and the positions of the contacts <NUM> of the socket type connector <NUM> at the time when temperature exceeds the melting temperature of the solder <NUM> and reaches <NUM> become the mounting positions of the contacts <NUM> on the first substrate <NUM>. Similarly, the positions of the contacts <NUM> of the plug type connector <NUM> at the time when the temperature reaches <NUM> become the mounting positions of the contacts <NUM> on the second substrate <NUM>.

As described above, ceramic, which is the material of the second substrate <NUM>, has a smaller thermal expansion coefficient than that of FR4, which is the material of the first substrate <NUM>. For this reason, assuming that the first cap <NUM> and the second cap <NUM> are materials with almost the same thermal expansion coefficient as that of the first substrate <NUM>, the first substrate <NUM> contracts while returning from <NUM> to <NUM>, and the interval between the contacts <NUM> of the socket type connector <NUM> also returns to the original interval. On the other hand, the second substrate <NUM> hardly contracts, and the interval between the contacts <NUM> of the plug type connector <NUM> remains widened by expansion. As a result, the mounting position error of the socket type connector <NUM> and the plug type connector <NUM> becomes large.

In contrast, as shown in <FIG>(B-<NUM>), when the thermal expansion coefficient of the second cap <NUM> is made smaller than the thermal expansion coefficient of the first cap <NUM>, the interval of the contacts <NUM> of the plug type connector <NUM> at the time of reaching <NUM> becomes smaller than that in the state where the thermal expansion coefficients are the same. Accordingly, the mounting position error of the socket type connector <NUM> and the plug type connector <NUM> at the time when the temperature returns from <NUM> to <NUM> becomes smaller.

The details of the present embodiment have been explained above. The connector set according to the present embodiment includes: a socket type connector <NUM>; a first cap <NUM> to be attached to the socket type connector <NUM> when the socket type connector <NUM> is reflow-mounted on the first substrate <NUM>; a plug type connector <NUM>; and a second cap <NUM> to be attached to the plug type connector <NUM> when the plug type connector <NUM> is reflow-mounted on the second substrate <NUM>, wherein the second substrate <NUM> is formed of a material with a smaller thermal expansion coefficient than that of the first substrate <NUM>, and the second cap <NUM> is formed of a material with a smaller thermal expansion coefficient than that of the first cap <NUM>. Accordingly, it is possible to absorb the difference between the thermal expansion coefficient of the material of the circuit board on which the socket type connector <NUM> is mounted and the thermal expansion coefficient of the material of the circuit board on which the plug type connector <NUM> is mounted, and reduce the mounting position error.

Further, the connector according to the present embodiment includes a plurality of socket type connectors <NUM> to be mounted on a first substrate <NUM>, and a plurality of plug type connectors <NUM> to be mounted on a second substrate <NUM>. The socket type connector <NUM> includes a first housing <NUM> with a slot <NUM>, and a plurality of contact <NUM> arranged in the slot <NUM>. The plug type connector <NUM> includes a second housing <NUM> with a header <NUM> to be fitted into the slot <NUM>, and a plurality of contacts <NUM> arranged in the header <NUM>. Then, the first housing <NUM> of the socket type connector <NUM> and the second housing <NUM> of the plug type connector <NUM> have a rotationally asymmetrical shape as viewed in a fitting direction. Thus, it is possible to provide a connector that is unlikely to cause reverse insertion.

Further, in the present embodiment, the slots <NUM> of the socket type connector <NUM> and the headers <NUM> of the plug type connector <NUM> are in two rows. For this reason, compared with one row in the conventional connector, it is possible to make it difficult to apply stress to the solder <NUM>.

Claim 1:
A connector set comprising:
a first connector and a first external substrate (<NUM>);
a first cap (<NUM>) to be attached to the first connector (<NUM>) to hold the first connector (<NUM>) when it is reflow-mounted on the first external substrate; and
a second connector (<NUM>) and a second external substrate (<NUM>); and a second cap (<NUM>) to be attached to the second connector (<NUM>) to hold the second connector (<NUM>) when it is reflow-mounted on the second external substrate formed of a material with a smaller thermal expansion coefficient than that of the external first substrate, wherein
the first connector (<NUM>) comprises:
a first housing (<NUM>) with a slot (<NUM>); and
a plurality of contacts (<NUM>) arranged in the slot (<NUM>), the first connector (<NUM>) arranged in a direction orthogonal to an extending direction of the slot (<NUM>)
the second connector (<NUM>) comprises a second housing (<NUM>) with a header (<NUM>) to be fitted in the slot (<NUM>), and a plurality of contacts (<NUM>) arranged in a direction orthogonal to an extending direction of the header (<NUM>), wherein when
the header (<NUM>) is fitted into slots (<NUM>), the contacts (<NUM>) of the first connector (<NUM>) are electronically connected to the contacts (<NUM>) of the second connector (<NUM>), characterised in that,
the second cap (<NUM>) is formed of a material with a smaller thermal expansion coefficient than that of the first cap (<NUM>).