Specifications subject to change without notice.
15801 Chemical Lane, Huntington Beach, CA 92649-1595
Tel: (714) 898-0960
•
Fax: (714) 896-0971
•
www.rho mbus-ind.com
Rhombus
Industries Inc.
SM-TECH 3/2001
SURFACE MOUNT APPLICATIONS
SM-1
GENERAL OVERVIEW:
Surface mount technology has been used on hybrid circuits for many years. Its greatest recent ad-
vance has been its use on printed circuit board (PCB) assemblies. Components are attached to the PCB
by soldering them directly to metalized solder pads (footprints) on its surface, rather than by insertion
through plated holes drilled into the PCB. The benefits of this technology as applied to PCB’s are sub-
stantial:
Ease in automation results in higher production throughput and better yields.
Closer spacing of components coupled with the ability to use both sides of the PCB for
component mounting results in significant savings in board real estate.
Closer spacing of components on the PCB surface significantly reduces the length of
signal traces thereby reducing stray capacitance and inductance, and improving the
overall performance characteristics of the circuit.
Reduced board cost by elimination of plated through-holes, a major portion of PCB costs.
Board rework costs and time are significantly reduced.
Many manufacturers have setup production lines that provide for both through-hole and surface
mount components to be utilized on the same PCB. This has been a necessity in the past since many
components have only recently been available in standard surface mount versions. It also provides for a
relatively smooth and calculated transition into the technology of surface mounting.
Many OEMs have wanted to enter the surface mount arena but were reluctant, due to the large
investments necessary for both equipment and personnel. To circumvent this large up-front investment,
they have contracted to assembly houses which specialize in this technology. This route provides any
OEM the ability to reap the many benefits of surface mount technology.
RHOMBUS SURFACE MOUNT PRODUCTS:
Through the use of our own in-house developed, and built automatic handling equipment, and induc-
tive components designed and built specifically for use on our new product lines, Rhombus is able to offer
cost effective, highly reliable product lines for through-hole as well as surface mount applications.
Rhombus has an extensive offering of surface mount delay lines and pulse transformers. All of our
new style delay line products are offered in either GULL WING or J-STYLE surface mount configura-
tions at no extra cost. Please refer to our Product Master List in the catalog index (section 1) for types
and availability.
EVALUATION PROGRAM:
Rhombus has conducted extensive reliability and qualification testing both in-house and at the
facilities of our major surface mount customers. The products have been designed for, and extensively
used in both vapor-phase and infrared reflow systems. The evaluation/qualification program was con-
ducted on the AIDM-XXX, AMDM-XXX, and the AITD-XXX series of products. These devices represent
the span of component densities, and construction details that would be used in any and all surface
mount applications including custom designs. All internal components used in our new product lines are
assembled to Alloy 42 lead frame utilizing 10Sn 90Pb solder. This reflects a solidus temperature of 268
Specifications subject to change without notice.
15801 Chemical Lane, Huntington Beach, CA 92649-1595
Tel: (714) 898-0960
•
Fax: (714) 896-0971
•
www.rho mbus-ind.com
Rhombus
Industries Inc.
SM-TECH 3/2001
SURF ACE MOUNT APPLICA TIONS
FIGURE 26: Recommended footprint, 14- pin G- Style. FIGURE 27: Recommended footprint, 8- pin G- Style.
degrees Centigrade (268°C = 514°F Solidus) and a liquidus temperature of 298 degrees Centigrade (290°C = 554°F
Liquidus). The transfer molded package utilizes the highest Electrical Encapsulation Grade epoxy currently available and
has been carefully checked for compatibility with all internal components and lead frame members. Rhombus has also
incorporated all of the above qualities into our auto-insertable through-hole series.
RECOMMENDED SOLDER PADS (Delay Lines):
Standard Gullwing SMD
Rhombus developed its Gull Wing lead configuration to fit on STANDARD versions (see 14-Pin below) of
industry accepted solder pads for SOL (small outline large .300 Wide) devices:
Figure 26 represents the 14-pin GULL WING solder pad we recommend and
is basically the equivalent of the industry standard SO-28 footprint utilizing
every other pad (i.e. lead centers are .100" instead of .050").
Figure 27 represents the 8-pin GULL WING solder pad we recommend and is
basically the equivalent of the industry standard SO-16L wide footprint utilizing
every other pad (i.e. lead centers are .100" instead of .050" ).
.100
(2.54)
.050
(1.27)
TYP. TYP.
.460
(11.68)
.320
(8.13)
.070
(1.78)
TYP.
.100
(2.54)
.050
(1.27)
TYP. TYP.
.460
(11.68)
.320
(8.13)
.070
(1.78)
TYP.
SM-2
.400 (10.16)
.430 (10.92)
.030
(0.76)
TYP.
.008 R
(0.20)
.100
(2.54)
TYP.
.050
(1.27)
TYP.
.020
(0.51)
TYP.
.010
(0.25)
TYP.
.505
(12.83)
MAX.
.285
(7.24)
MAX.
.785
(19.94)
MAX.
.050
(1.27)
TYP.
.020
(0.51)
TYP.
.100
(2.54)
TYP.