IPC-CM-770D-1996.pdf - 第76页

IPC-CM-770 Januaty 1996 INSERTED OMPONENT ELASTOMERIC SEAL P IPC-1-00238 Figure 16-1 Low Profile Pluggable Devices Figure 16-2 Low Profile Devices mm, 1.32 mm, 1.57 mm, 1.83 mm and 2.54 mm which should be maintained for …

January

1996

IPC-CM-770

Figure 15-1

Surface Mount Receptacle

Figure 15-1

Box-contact Surface Mount Receptacle

Stake-to-the-Board Devices

that are mounted horizon-

tally or vertically. They are usually manufactured as either

dual or multimetal devices, or as singular metal devices.

B. Low Profile Pluggable Devices

assumes positive reten-

tion to the printed board prior to soldering. They usually

are designed with a cup and spring extension that allows

solder to be drawn to the top surface of the board, produc-

ing a solder fillet on the component side land without over-

flow into the socket.

C. Low Profile Grip Type Devices

are miniature connec-

tors with a singular metal device that has a portion acting

as a temporary retention device for discrete component

leads,

that they may be eventually soldered and, if nec-

essary,eventually removed easily without damage to the

board or to the component being removed.

16.1.1 Individual Component-Lead Sockets

16.1.1.1 Low Profile Sockets

One such device is a plug-

gable socket that assumes positive retention in the board

prior to soldering, and spring to board electrical contact

after soldering. The design of the cup and spring extension

allows solder to be drawn to the top surface of a two-sided

board, producing a solder fillet on the top land without

overflow into the socket. Soldering may be done by the

usual methods of wave soldering or hand soldering.

The socket shown is of two-part design having a heat

treated spring assembled into a drawn cup. Spring provides

multiple cycle life with high contact forces.

Many of these components come with an elastomer seal to

keep out contaminants during the soldering, washing cycles

as well as throughout its life and care must be taken during

insertion into the board

as not to destroy this seal. The

seal is normally left in position throughout the life of the

socket and discrete components are mounted or inserted

through it without detrimental effects. See Figures 16-1 and

16-2.

The profile of this type of device above the printed board

usually is less than

0.8

mm and can be used on centerline

spacings as close as 2.54 mm minimum center to centerline

distance. Product is available for nominal hole sizes of

1.07

4-1

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IPC-CM-770

Januaty

1996

INSERTED

OMPONENT

ELASTOMERIC

SEAL

IPC-1-00238

Figure 16-1 Low Profile Pluggable Devices

Figure 16-2 Low Profile Devices

mm, 1.32 mm,

1.57

mm, 1.83 mm and 2.54 mm which

should be maintained for retention purposes in soldering

operations.

Devices of this type can accommodate round lead sizes

from 0.254 mm to 1.65 mm and square or rectangular

devices with equivalent diameters.

Four styles of product can be used in each of the hole sizes.

Closed Bottom

to accommodate standard applications

which are compatible with hand, wave or vapor phase sol-

dering. (See Figure 16-3.)

Open Bottom

for feed thru applications which are hand

soldered.

Knockout Bottom

for feed thru applications which

allow the use of wave or vapor phase soldering-the pres-

heared bottom is removed after soldering to complete the

feed thru application.

Bullet Nose

design allows greater positional tolerance

for high speed applications on bench or numerically con-

trolled equipment.

16.1.1.2 Low Profile Grip Type Device

This type of

miniature connector is a singular metal device having a

portion acting as a temporary retention device for compo-

nent leads

that they may be eventually soldered and, if

necessary, eventually removed easily without damage to

the board. They are designed to reduce or eliminate many

of the problems associated with component mounting prior

to solder reflow or solder processing.

They give a mechanical through connection that will resist

impact, vibration and thermal shock. They are retained in

IPC-1-00383

Figure 16-3 Closed Bottom Socket

the board by flaring of the lower edge, the upper edge hav-

ing been flared in manufacture. They may be used in plated

through or non-plated through-holes, multisided or single-

sided boards and may be hand or machine inserted. See

Figure 16-4.

Before flaring After flaring

Cross

section

IPC-I-O0240

Figure 16-4 Low Profile Grip Type Device

These devices help resist component movement which in

turn reduces solder defect failures. They assist in the reduc-

tion of damage when replacing components.

IPC-I-O0242

Figure 16-5 Use of Low Profile Grip Devices

In many cases, it is not necessary to use spacers since the

device retains a firm hold on conductors throughout normal

produc- tion handling at the depth inserted. Heat sensitive

components are held at a safe distance from the board. See

Figures 16-5 and 16-6.

16.1.2 Multiple-Lead Component Sockets

Sockets are

4-8

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Januaw

1996

IPC-CM-770

FlJNNEL

FLAT

HOLLED

IPC-1-00243

Figure 16-6 Styles of Low-Profile Grip Devives

provided for an extremely wide assortment of component

types. The major use, however, is for semiconductor pack-

age styles. These semiconductors and most other compo-

nent styles are defined extensively in EIA (Electronic

Industry Association) standards and won't be repeated

within this document.

Although sockets are normally associated with the inserted

component names, they most generally fall into several

broad socket contact categories which vividly describe

their type.

Component named sockets utilizing these different contact

types are listed in Table 16-1. Contact styles vary with each

socket dependent on the supplying vendor. Figure 16-7

shows a cross section of various socket types available.

16.1.2.1 DIP Sockets

Sockets of this type are designed

for low cost, high density production packaging. They have

universal mounting and packaging capabilities. Sockets are

available with a "solder tail" in 14-, 16-, 24- and 28-lead

configurations. They are generally designed to resist solder

wicking into the socket cavity. Sockets of this type may be

inserted into a printed board manually or automatically.

Many are designed with standoffs which allow for ease and

thorough cleaning after application to the printed board and

are ventilated to assist cooling of components. IC leg tar-

get areas or lead-in should be large and target areas

1.1

1.5

mm or larger are not uncommon. Large "lead-in"

facilitates IC leg entry.

Many factors affect IC socket performance. Consider con-

tact plating materials (gold, tin and tin-lead alloys); socket

body construction; insulating materials (thermoplastic and

thermoset plastics); standard profile-8.3 mm versus low

profile-4.44 mm; and the retention force needed for a par-

ticular application.

Housing length is dependent upon the number of lead con-

figurations. Average force to insert a package or a printed

board varies from 7 pounds on an 8-position part to 13

pounds on a 16-position part. (See Figure 16-8.)

TContact

Houslng

Slngle Wlpe

Devlce-

~ Single wipe. slde gulde

~ Dual wlpe D ~

Box

~ Screw machlne

losed Posltlon

Rest

Posltlon

Cam

Horlzontal beam

"J"

lead

~ Bellows

~ Zero Insertion J ~ Leaf

IPC-1-00244

Figure 16-7 Contact Configurations

4-9

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