pertains to the process of evaluating the solderability of terminations
(i.e., component leads, lugs, terminals, wires, etc.). Industry
standards for performing solderability testing include the following: 1)
Mil-Std-883 Method 2003
- "Solderability"; 2) IPC/JEDEC
J-STD-002 - "Solderability Tests for Component
Leads, Terminations, Lugs, Terminals and Wires";
IPC/JEDEC J-STD-003 - "Solderability Tests for Printed Boards";
JESD22-B102; and 5) Part 21 of the IEC 60749.
surface is defined by its solder wetting characteristics.
the formation of a relatively uniform, smooth, and unbroken film of
solder that exhibits excellent adherence on the soldered surface.
on the other hand, is the condition wherein the solder coating has
contacted the surface but did not adhere completely to it, causing the
surface or a part thereof to be exposed.
condition wherein the solder recedes after coating a surface, creating
irregular mounds of solder, but leaving behind
several ways by which solderability testing is done, but the
used methods are: 1) the Dip and Look Method; and 2) Wetting
Balance Analysis. In both of these tests, the samples undergo an
accelerated 'aging' process before being tested for solderability, to
take into consideration the natural aging effects of storage prior to
Dip and Look
which is widely used in process QA and reliability monitoring, is a
qualitative test process, i.e., judgment on whether a sample passes or
fails the test is based on the physical and visual attributes that it
on the other hand, is a quantitative test, i.e., it measures the wetting
imposed by the molten solder on the test surface as it is dipped into
and held in the solder bath as a function of time and plotted. The plot
starts with the wetting force being negative (non-wet condition), which
rises until it crosses the
of wetting force, indicating that wetting has occurred. The time it
takes for wetting to occur is one parameter used to assess
are, however, no established industry-standard pass/fail criteria for
wetting balance analysis, which is why it is used primarily as an
engineering tool and not as a production monitor. Wetting force
on the density and surface tension of the solder.
Mil-Std-883 Method 2003 - Solderability Testing
is one of the oldest and most widely used standards for solderability
testing. It will be used as the basis in the discussion below to provide
more details on how solderability testing is normally done.
|You May Like These|
|Disturbed Friends - This game should be banned|
|Smart Ass, the game where it's OK to yell out the answer, even when it's not your turn|
Method 2003 employs the Dip and Look Method, requiring the following
1) a solder pot of sufficient size that can maintain solder at a
specified temperature; 2) a dipping mechanism capable of controlling the
rates of immersion and emersion, as well as dwell time, of the
terminations; 3) an optical and lighting system that facilitates
inspection at a minimum magnification of 10X; and 4) steam aging
equipment for 'aging' the samples prior to testing.
the following steps:
of the samples as defined by the acquisition document, but which must
not include wiping, cleaning, scraping, or abrasive cleaning of the
terminations to be tested;
samples in a steam ager, which consists of exposing the surfaces to be
tested to water vapor for 8 hours and drying them either by baking at
100 deg C for no more than 1 hour in a dry atmosphere or air drying them
at ambient temperature for a minimum of 15 minutes;
application of flux
which consists of immersing the terminations in static solder at a
uniform temperature of 245 +/- 5 deg C; and 5)
of the terminations
criterion for acceptable solderability is
of the dipped portion of the terminations by a new and continuous solder
coating. Thus, pinholes, voids, porosity, nonwetting, or dewetting
exceed 5% of the total dipped area.
Mil-Std-883 Method 2003 (please see the said spec for complete details)
Test or PCT; Temperature
Heat Resistance Test (SHRT);
Reliability Modeling; Qualification
Package Failures; Die
All Rights Reserved.