HANDLING - MOUNTING - USE

for Surface Mount SOP Sockets



HANDLING

As with any close pitch surface mount device, good lead alignment and coplanarity are essential. You can avoid mounting problems by observing the following:

  • Your sockets will be shipped in a protective package. It is recommended that you keep them protected until you are ready to mount them.

  • Your sockets will be shipped in a protective package. It is recommended that you keep them protected until you are ready to mount them.

  • During handling, avoid coming in contact with the terminals. This will minimize the potential for damage or contamination which may adversely effect solderability.


MOUNTING

To assist you in the creation of your PC board artwork and component layouts, a disk of DXF files is available. These design aids can be imported into most popular CAD software. Contact A P Products for your copy...ask for the disk titled "SKTDES01".

We suggest using one of two methods for mounting your sockets. The most conventional way is to reflow solder them in either a convection or a combination convection/infrared oven. The use of an exclusively infrared oven may not yield the desired solder joint quality and, in fact, may lead to damage to the socket.

Though your final reflow soldering profile will be unique for your product, here's a suggested starting point.




Zone
Upper Setting
Lower Setting
#1
175
175
#2
125
125
#3
125
125
#4
180
180
#5
150
150
#6
150
150
#7
220
220
#8
255
300
Line Speed = 28 Inches/Min

Suggested Convection/I.R. Reflow Soldering Profile
for Meritec Surface Mount SOP Sockets




When soldering, these points should be noted:


  • Solder mask must be present between the device pads. Be aware that a number of PC board manufacturers are not yet capable of applying it satisfactorily between the closely spaced pads of a TSOP or SSOP pattern.

  • The solder paste stencil should be of a high quality, .006" thick stainless steel.

  • A suggested solder paste is #6-SN63-465-C, Series 400 available from ESP, Inc. Its fine grained consistency and use of water soluble flux has yielded good results.

  • Use a flux with an activity level strong enough for surface mounted devices.

  • Apply flux sparingly...excessive flux may wick up into the terminal area, restricting terminal movement.

  • Observe the expiration date on the flux or solder paste container.

  • Take care to assure that solder paste is applied only to the solder pads. Close-pitch devices such as these bridge easily.

  • Because the socket terminals are PbSn plated, the use of lead-free solders is NOT recommended. Their use may result in unexpected cosmetic or structural problems in the solder joint.

  • The plastic components of the socket may be damaged if exposed to a temperature exceeding 230 degrees C.


A viable alternative to soldering is conductive epoxy. They are available in both isotropic or anisotropic versions. The former is equally conductive in all directions...the latter is conductive across its thickness only. Though anisotropic is preferred, isotropic CAN be used to mount the larger pitch PSOP socket. The following should be observed:

  • The applied thickness of a paste epoxy must be <.003" (0.08mm) to prevent wicking up into the terminal slot during curing.

  • As with reflow soldering, the use of a convection or combination convection/infrared oven is suggested. Satisfactory results may also be achieved with the careful application of a heat gun.

  • Cure per epoxy manufacturer's instructions, but do not exceed the temperature limit defined above.

One further suggestion regarding the use of anisotopic epoxy... A common requirement for a quality connection with these materials is the application of pressure during the cure cycle. This forces the conductive particles together, forming the electrical path. If, at a later time, it is exposed to a temperature exceeding the epoxy's softening point, the film may relax and the conductive path will be broken. So...consider carefully what subsequent processes your product may undergo and what it's end use is...you may feel more secure using solder.

Hand soldering is NOT recommended. Tip temperature of soldering irons may degrade or distort the plastic components of the socket. If a resin core solder is used, the flux may wick up into the terminal area, causing intermittent opens between the terminal and the SOP device.

Whether you are soldering or using anisotropic epoxy to mount your sockets, Meritec recommends that the lock be in the unlocked position during the heat cycle.



USE

The Meritec SOP Sockets have a positive locking lid design. The lock is attached to the left lid and slides back and forth in a direction parallel to the hinge pins. Your sockets will be shipped in the locked condition.



To open them, first slide the lock sideways (approximately 1mm) to the unlocked position.



Both lids are now free to be opened by rotating them on their respective hinges.



Place the SOP component into the socket.


The lids must be closed simultaneously to assure proper seating of the SOP component. If this is not observed, the component will shift off center in the socket resulting in an unsatisfatory electrical connection. Now, while maintaining a downward pressure on the lock, slide it sideways to its locked position.

The Meritec socket was designed to accommodate as generously as possible, the full range of dimensions published in the current JEDEC "SOP" specifications. The following drawing and table define the acceptable dimensional limits of "SOP" packages for use with Meritec sockets.






Dimensional Limits of SOP Packages
for Mating With Meritec Surface Mount SOP Sockets
DIM 40 TSOP
Min - Max
48 TSOP
Min - Max
56 TSOP
Min - Max
44 PSOP
Min - Max
56 SSOP
Min - Max
PL
PL*
PH
BL
BW
SH
E
LP
LW
LT
LL

LC
0,777 - 0,795
0,786 - 0,795
-------- - 0,047
-------- - 0,732
-------- - 0,402
0,002 - --------
0,006 - 0,014
0,0197 Nom
0,0065 - 0,0100
0,0045 - 0,0075
0,020 - 0,028
0° - 5°
-------- - 0,004
0,777 - 0,795
0,786 - 0,795
-------- - 0,047
-------- - 0,732
-------- - 0,481
0,002 - --------
0,006 - 0,014
0,0197 Nom
0,0065 - 0,0100
0,0045 - 0,0075
0,020 - 0,028
0° - 5°
-------- - 0,004
0,777 - 0,795
0,786 - 0,795
-------- - 0,047
-------- - 0,732
-------- - 0,559
0,002 - --------
0,006 - 0,014
0,0197 Nom
0,0065 - 0,0100
0,0045 - 0,0075
0,020 - 0,028
0° - 5°
-------- - 0,004
0,620 - 0,637
0,628 - 0,637
-------- - 0,116
-------- - 0,531
-------- - 1,118
0,004 - --------
0,026 - 0,034
0,050 Nom
0,014 - 0,020
0,0045 - 0,0075
0,030 - 0,033
0° - 8°
-------- - 0,004
0,620 - 0,637
0,628 - 0,637
-------- - 0,073
-------- - 0,531
-------- - 0,941
0,004 - --------
0,037 - 0,045
0,0315 Nom
0,011 - 0,016
0,0045 - 0,0075
0,030 - 0,033
0° - 6°
-------- - 0,004
All Dimensions in Inches

PL
PL*
PH
BL
BW
SH
E
Package Length
Package Length (Shifted)*
Package Height
Body Lenght
Body Width
Standoff Height
Edge Offset
LP
LW
LT
LL

LC
Lead Pitch
Lead Width
Lead Thickness
Lead Lenght
Lead Angle
Lead Coplanarity

* These are the dimensional limits if the lids of the socket are NOT closed simultaneousely and the package is permitted to shift... See preceeding text.

On occasion, you may encounter "SOP" components which are still within JEDEC specs, but fail to make satisfactory connection with the Meritec socket. This is most likely to occur with respect to dimensions "PL" and "LW" in the table above, and is an indicator of marginal component quality.

Fortunately, most component manufacturers embrace quality philosophies (such as Taguchi's) which are more advanced than the "goalpost" thinking of 2 decades ago. So long as your component manufacturer is capable of producing with a Cpk of 1.33 or greater to the JEDEC specifications, you should have good results using the Meritec sockets.

We hope that you've benefited from these application tips. If you require further assistance, please contact A P Products.




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Last update March 1, 1998