IPC-CM-770D-1996 - 第71页

IPC-CM-770

Januaty

1996

I I

insulation displacement slot, press fit pin, or solder. Note

IPC-I-O0062

Figure 15-1 Typical Polarization

that housing can be designed to provide some board

support.

15.3.1.1 Plug (Card Edge) Connectors

These connec-

tors use conductors at the edge of the board as a portion of

the connector. The arrangement may be similar to that in

15.3.1.2

or directly to cable or discrete wire connector.

Examples are shown in Figures

15-3

and

15-4.

15.3.1.2 Receptacle Connectors

A

most common and

versatile arrangement is the use of a card cage.

A

large

board is provided with male pins and appropriate intercon-

nection circuits or solderless wrapping connections. Subcir-

2

54

mm

(O

100

In)

(O

400

In)

10 16

mm

TYP

Dia

Ref

IPC-I-O0228

L

Figure 15-2 Connector with Keying and Polarization

15.2.3 InputdOutputs

In order to minimize board space

required by connectors, consideration must be given to

high pin count connectors, or connectors with reduced cen-

terline spacing.

15.2.4 Processing

The processing a connector is

exposed to plays a major role in selection. Elevated tem-

perature exposure adds constraints to plastic selection. Mis-

matches in the coefficient of thermal expansion (CTE)

I

IPC-I-O0229

Figure 15-3 Card Edge Connector to Ribbon Cable

between the connector and substrate affect selection and

lead design. Cleaning processes effect connector selection

due to design considerations and chemical compatibility.

15.3 Part Type Descriptions

When discussing board

I!

-,

mounted connectors, they can be divided into two general

categories, card edge, integral, and two-part. Variations of

;i

each type include through and surface mount, male and

y

female and press-fit.

15.3.1 Integral (One-Piece) Connectors

Card edge or

integral connectors use the conductor paths of the printed

board as contacts. The connector serves to provide a suit-

Figure 15-4 Card Edge Connector for Discrete Wiring

able interface between the printed board and a cable, dis-

crete wires, or another printed board. Generally, the non- cuits are connected to this mother board by card connectors

separable interface is created by means of a crimp, as shown in Figure

15-5.

A

similar design can be used with

- -

.

.\

IPC-I-

4-2

COPYRIGHT Association Connecting Electronics Industries

Licensed by Information Handling Services

COPYRIGHT Association Connecting Electronics Industries

Licensed by Information Handling Services

January

1996

IPC-CM-770

internal connectors, but the special board preparation usu-

ally results in higher costs.

wrap, press-fit pin or solder. Housing enhancements may

include card support, printed board, or connector latches

(locks) and polarizationkeying features. (See Figure

15-7.)

-1-00085

Figure 15-5 Card Guide Connector

15.3.2 Discrete-Contact (Two-Part) Connectors

In

recent years, two-part connector systems have become

quite popular as a means of interconnecting mother boards

to daughter boards. The system consists of a permanently

mounted male on one board and a mating permanently

mounted female on the other board. Male headers can be

soldered or press fit into the board. Another variation is to

put pins into the board (solder or press fit), and then press

a shroud over the pins to form a header. Female recep-

tacles are usually soldered to the board. Both straight and

right angle versions are common. Examples of a two-part

system are shown in Figure

15-6.

r

Figure 15-6 Two-piece Connector System

15.3.2.1 Pin Contact (Male) Connectors

Contacts char-

acterized by a pin at the separable interface are male con-

nectors. The opposite or permanent inter- face may utilize

such methods as crimp, insulation displacement slot, wire

IPC-1-00232

Figure 15-7 Header Connectors

15.3.2.2 Socket-Contact (Female) Connectors

Female

connectors consist of some type of socket terminals within

a dielectric housing. There are an infinite variety of styles

to provide necessary requirements. The terminals can be

arranged for mating of boards which are parallel or at right

angles to each other. Examples of female receptacles are

shown in Figure

15-8.

15.4 Through-Hole Mount Connectors

Through-hole

mount connectors are designed to mount to the printed

board with the leads extended through the board. The leads

are then typically soldered in place to permanently mount

the connector to the board. A variety of connectors,

employing a compliant section in a pin are available. The

compliant section allows installation in a plated through-

hole without the need for soldering. The interference fit

between the compliant section of lead and plated-through-

hole achieves a reliable gas tight interconnection. Installa-

tion of this type requires the use of an arbor press with

suitable tooling. An example can be seen in Figure

15-9.

Connectors may be mounted to the printed board by solder-

ing, welding, crimping, press fitting or other means; leads

may be extended through-hole or contact may be made to

circuit lands provided on the board, holes may be plated

through or simply drilled. The exact method will depend on

the connector design. Board size and weight are important

factors in choosing connector mounting hardware, and in

deciding whether the board will be mounted horizontally or

vertically. It is common practice to mount the connector

4-3

COPYRIGHT Association Connecting Electronics Industries

Licensed by Information Handling Services

COPYRIGHT Association Connecting Electronics Industries

Licensed by Information Handling Services

IPC-CM-770

Januaty

1996

lnrulallon Support

Wir.

Crimp

Rac*ptmclo

IPC-1-00233

Figure 15-8 Female Receptacles

IPC-1-00235

I

Figure 15-9 Connector with Press Fit Contacts

either to a mother board or to card racks or frames, then

insert the component board into the connector using appro-

priate guiding and support mechanisms. In general, if the

board is mounted horizontally, or if vibration is to be

encountered, the board should be attached to the connector

or supported by mechanical means other than contact

friction.

Press fit headers require special tooling to apply the header

to a board. Tooling can vary from simple hand fixtures to

elaborate presses depending on part size and connector

design.

Connectors with low line densities can be installed manu-

ally. Higher concentrations will require card ejectors, jacks,

or guide pins. So-called zero insertion force connectors are

available which require an auxiliary force to make connec-

tions after the card is inserted into the connector.

Note: Many versatile connectors are available for the

printed board designer to transfer signals or power to the

boards. Careful attention to the uses and requirements of

these devices will result in reliable interconnections.

Connectors with integral retention to the board are favored

for manufacturing ease. Connectors that cannot be snapped

or clinched in place prior to soldering require mechanical

fastening. This is primarily for positioning and the connec-

tor must then be soldered to assure electrical integrity.

15.4.1 Component Preparation

Examination of the

leads is recommended. The assembler should look for

grossly bent leads, poor plating, and loose debris.

15.4.2 Land Patterns

Connectors are available for a

variety of land patterns including inline and staggered.

Commercially available pitches are

0.127

mm and greater.

15.4.3 Lead Configuration After Assembly

Connector

leads are generally selectively crimped for retention.

15.4.4 Mounted Component Configurations

Lead and

hole location become more critical as the number of I/Os

increase. Chamfered leads are recommended for large con-

nectors. As in any multi-lead device, the true position of

pattern clusters becomes critical for reliable installation and

ease of manufacturing. The use of a secondary reference

such as a hardware hole is recommended. Connector manu-

facturers should be contacted for installation aids

availability.

15.5 Surface Mounting

Surface-mount connectors are

designed with compliant leads which are usually reflow

soldered to the lands located on the surface of a board.

Although not as popular, alternate methods of attachment

at the non-separable interface include pressure and conduc-

tive epoxy. Connectors designed for surface mount carry

the implicit qualities associated with high-temperature,

dimensionally stable materials. Examples of surface mount

connectors are shown in Figures

15-10

through

15-13.

Connectors for surface mounted substrates differ from

through mounted connectors in several important aspects.

The plastic insulator material must be chosen to withstand

4-4

COPYRIGHT Association Connecting Electronics Industries

Licensed by Information Handling Services

COPYRIGHT Association Connecting Electronics Industries

Licensed by Information Handling Services