IEC 60749-15 pdf download – Semiconductor devices – Mechanical and climatic test methods – Part 15: Resistance to soldering temperature for through-hole mounted devices
1 Scope
This part of lEC 60749 describes a test used to determine whether encapsulated solid statedevices used for through-hole mounting can withstand the effects of the temperature to whichthey are subjected during soldering of their leads by using wave soldering or a soldering iron.
ln order to establish a standard test procedure for the most reproducible methods,the solderdip method is used because of its more controllable conditions. This procedure determineswhether devices are capable of withstanding the soldering temperature encountered in printedwiring board assembly operations,without degrading their electrical characteristics or internalconnections.
This test is destructive and may be used for qualification， lot acceptance and as a productmonitor.
This test is,in general, in conformity with lEC 60068-2-20 but, due to specific requirements ofsemiconductors, the clauses of this standard apply.
General
The heat is conducted through the leads into the device package from solder heat at thereverse side of the board. This procedure does not simulate wave soldering or reflow heatexposure on the same side of the board as the package body.
3 Test apparatus
3.1Solder pot
A solder pot of sufficient size to contain at least 1 kg of solder shall be used.The solder potdimensions shall allow full immersion of the leads without touching the bottom.The apparatusshall be capable of maintaining the solder at the temperature specified in Table 1.
3.2Dipping device
A mechanical dipping device shall be used that is capable of controlling the rates ofimmersion and emersion of the leads and providing the dwell time as specified in Table 1.
3.3 Heatsinks or shielding
lf applicable, heatsinks or shielding shall be attached to the devices prior to the test and shallbe as specified in the relevant specification.
4Materials
4.1Solder
The solder specification shall be as follows.Chemical composition
for SnPb solder the composition in percentage by weight shall be as follows:Tin:59 % to 65 %;
Lead:the remainder.Chemical composition
– for Pb-free solder the composition in percentage by weight shall be as follows:
Silver:3 % to 4 %;
Copper:0.5 % to 1 %;Tin:the remainder.
The solder shall not contain impurities which will adversely affect its properties.
Other solders and their applicable bath temperatures may be used as specified in the relevantspecification.
4.2Flux
lf flux is applied prior to solder dipping, the flux shall consist of 25 % by weight of colophonyin 75 % by weight of isopropyl alcohol, unless otherwise detailed in the relevant specification.”
5Procedure
5.1 Pre-conditioning of specimens
Any special pre-conditioning of the specimens prior to testing shall be as specified inthe relevant specification.This preparation may include operations such as bending or otherrelocation of leads,and the attachment of heat sinks or protective shielding prior tosolder dipping.
5.2Preparation of the solder bath
The molten solder shall be stirred to assure that the temperature is uniform.The dross shallbe skimmed from the surface of the molten solder just prior to dipping the part.
5.3Use of flux
Where detailed in the relevant specification,all leads of the specimen shall be dipped in fluxprior to solder dip; excess flux shall be removed by draining for a suitable time.
5.4Solder dip
The part shall be attached to the dipping device (see 3.2) and the leads immersed in themolten solder until the body of the device under test reaches the dimensions specified inTable 1.The parameters for solder temperature,dwell time， number of immersions and ratesof immersion and emersion are defined in Table 1. Unless otherwise detailed in theprocurement specification, Condition A shall be used.After the dipping process, the part shallbe allowed to cool in air and，if flux has been used，residues shall be removed withisopropanol or ethanol.
5.5Precautions
Prior to and after the solder immersion，precautionary measures shall be taken to preventundue exposure of the part to the heat radiated by the solder bath.
5.6Measurements
Hermeticity tests for hermetic devices，visual examination and electrical measurements thatconsist of parametric and functional tests, shall be made as specitied in the relevantspecification.
5.7 Failure criteria
A device shall be defined as a failure if hermeticity for hermetic devices cannot bedemonstrated，if parametric limits are exceeded or if functionality cannot be demonstratedunder nominal and worst-case conditions specified in the relevant specification. Mechanicaldamage such as cracking, chipping or breaking of the package (10x -20x magnification) willalso be considered a failure, provided such damage was not induced by fixturing or handling.
6 summary
The following details shall be specified in the relevant specification:a) use of heatsinks or shielding, if applicable (see 3.3);
b) flux composition if applicable (see 5.3);
c) older composition if other than detailed in this standard (see 4.1);d) pre-conditioning of specimens, if applicable (see 5.1);
e) condition(A or B), time and depth of immersion, if other than as specified in Table 1;f) method of hermeticity tests, visual examination and electrical measurements (see 5.6);g) failure _criteria of hermeticity tests，visual examination and electrical measurements(see 5.7);
h) sample size.
IEC 60749-15 pdf download – Semiconductor devices – Mechanical and climatic test methods – Part 15: Resistance to soldering temperature for through-hole mounted devices
