4608X-102-102 Datasheet, PDF (60/62 Pages) Bourns Electronic Solutions – Resistor Networks Product Selection Guide

Soldering And Cleaning Processes
This application note is designed to provide step-by-step processing recommendations. It covers
the popular soldering process currently in use and provides recommendations and cautions for
each step. Since many variations of time, temperature, processes, cleaning agents and board
types in use, you will want to verify your own system. Bourns does not recommend the backside
mounting of passive components.
The process steps, recommendations and cautions are based on Bourns surveys of users, equip-
ment manufacturers and materials suppliers. No warranty expressed or implied is made in regards
to the following recommendations.
1
Solder Paste
Printing
Reflow; Convection,
IR and Vapor Phase
GENERAL
Use the optimum
solder paste for the pattern,
printing process, and sol-
der joint quality.
RECOMMENDED
Typical solder paste alloy is
63Sn/37Pb. RMA,No-Clean
or Halide Free Water
Soluble fluxes should be
used.
CAUTION
Since solder paste usually
contains a high percentage
of activators, you must
ensure adequate cleaning
to remove all residues.
Consult your solder paste
supplier for cleaning meth-
ods. When cleaning addi-
tives are needed, only
those that are Halide Free
should be used.
2
Adhesive
Application
GENERAL
The adhesive must hold the
unit in correct orientation
upon placement and main-
tain the correct position
during any physical han-
dling before the final sol-
dering process.
RECOMMENDED
To assure positional stabili-
ty, place a single dot of
epoxy under the unit.
Epoxy
CAUTION
Use sufficient adhesive to
assure stability through the
cure process.
Avoid overflow of epoxy
onto solder pads and termi-
nal areas.
Excessive curing before
placement may not allow
full seating of the part
causing incomplete solder
connections.
3
Network
Placement
GENERAL
Use pick-and-place equip-
ment with a vacuum nozzle
ID that allows adequate
suction to pick the unit out
of the pocket cavity.
RECOMMENDED
Ensure nozzle inside diam-
eter and vacuum levels are
adequate to maintain suc-
tion and part alignment.
CAUTION
Ensure parts are placed so
that all leads are centered
on the solder pads.
Align the leads with the sol-
der belt direction of travel
to avoid the part body cre-
ating a thermal shadowing
effect.
Excessive placement force
to the part should be avoid-
ed to minimize the risk of
package damage.
4
Adhesive
Cure
GENERAL
Heat/time cure should be
accomplished using either
an infrared radiation or a
convection oven.
RECOMMENDED
Cure using the temperature
profile specified by the adhe-
sive manufacturer.
CAUTION
Use sufficient cure time to
ensure complete adhesive
transition from fluid to solid.
Care should be taken to
assure the placed units are
not exposed to temperatures
in excess of the manufactur-
er's maximum.
Do not exceed the maximum
temperature rating of the
component.
5
Flux
Application
Flow (Wave)
GENERAL
Use the correct flux to
remove surface oxides,
prevent re-oxidation and
promote wetting.
RECOMMENDED
RMA (Rosin Mildly
Activated) flux or Halide
Free Water Soluble flux is
recommended.
CAUTION
Avoid fluxes with Halide
activators.
336
Specifications are subject to change without notice.