Usually, the inspection items for electroplating products are: film thickness, adhesion, solderability, appearance, package, and salt spray test. For products with special requirements in drawings, there are porosity tests (30U”) using nitric acid vapor method, palladium nickel plated products (using gel electrolysis method) or other environmental tests.
I. Electroplating product inspection – film thickness inspection
1. Film thickness is a basic item for electroplating inspection, and the basic tool used is a fluorescent film thickness meter (X-RAY). Its principle is to use X-rays to irradiate the coating, collect the energy spectrum returned by the coating, and identify the coating thickness and composition.
2. Precautions for using X-RAY:
1) Spectrum calibration is required every time the machine is turned on
2) Cross line calibration is required every month
3) Gold and nickel calibration should be performed at least once a week
4) When measuring, the test file should be selected according to the steel used in the product
5) For new products that do not have a test file, a test file should be established
3. The significance of the test file:
Example: Au-Ni-Cu(100-221 sn 4%@0.2 cfp
Au-Ni-Cu———-test the thickness of the nickel-plated base and then gold-plated on the copper substrate.
(100-221 sn 4%——-AMP copper material number (copper material containing 4% tin)
II. Electroplating product inspection-adhesion inspection
Adhesion inspection is a necessary inspection item for electroplating products. Poor adhesion is the most common defect in electroplating product inspection. There are usually two inspection methods:
1. Bending method: first use a copper sheet of the same thickness as the required test terminal to pad the bending part, use flat-nose pliers to bend the sample to 180 degrees, and use a microscope to observe whether the coating peels or peels on the bending surface.
2. Tape method: Use 3M tape to stick firmly on the surface of the sample to be tested, vertically 90 degrees, quickly tear off the tape, and observe whether there is any peeling of the metal film on the tape. If it cannot be observed clearly by visual observation, a 10x microscope can be used for observation.
3. Result judgment:
a) There should be no falling metal powder and being stuck by the tape
b) There should be no peeling of the metal coating
c) If the base material is not broken, there should be no serious cracking and peeling after bending
d) There should be no blistering
e) The lower metal layer should not be exposed without the substrate being broken
4. When poor adhesion occurs, you should learn to distinguish the location of the peeled layer.You can use a microscope and X-RAY to test the thickness of the peeled coating to determine the workstation with the problem.
III. Electroplating product inspection-solderability inspection
1. Solderability is the basic function and purpose of tin-lead plating and tin plating. If there are post-soldering process requirements, poor soldering is a serious defect.
2. Basic methods of soldering test:
1) Direct tinning method: According to the drawing requirements, directly immerse the solder part in flux and immerse it in a 235-degree tin furnace. After 5 seconds, it should be slowly taken out at a speed of about 25MM/S. After taking it out, cool it to room temperature and observe it with a 10x microscope to determine: the tinned area should be greater than 95%, the tinned part should be smooth and clean, and there should be no solder rejection, desoldering, pinholes, etc., which is considered qualified.
2) Aging before welding. For products with special requirements on some force surfaces, the samples should be aged for 8 or 16 hours using a steam aging tester before the welding test to determine the welding performance of the product under harsh use environments.
IV. Electroplating product inspection – appearance inspection
1. Appearance inspection is the basic inspection item for electroplating inspection. The suitability of electroplating process conditions and possible changes in electroplating solutions can be seen from the appearance. Different customers have different requirements for appearance. Electroplated terminals should be observed with a microscope of at least 10 times. For defects that have occurred, the greater the magnification, the more helpful it is to analyze the cause of the problem.
2. Inspection steps:
1). Take the sample and place it under a 10x microscope, and illuminate it vertically with a standard white light source:
2). Observe the surface condition of the product through the eyepiece.
3. Judgment method:
1). The color should be uniform, without dark or light colors, or different colors (such as blackening, redness, or yellowing). Gold plating should not have serious color differences.
2). No foreign matter (hair, dust, oil, crystals) should be allowed to stick to it
3). It must be dry and not wet
4). Good smoothness, no pits, particles
5). No deformation such as crushing, scratching, and scraping, and damage to the plated parts
6). No exposure of the lower layer. Regarding the appearance of tin-lead, a small amount (no more than 5%) of pits and pits are allowed without affecting the solderability.
7). The plating layer should not have blistering, peeling and other poor adhesion
8). The electroplating position is carried out according to the drawing requirements. Under the premise of not affecting the use function, the QE engineer can decide to relax the standards appropriately
9). For suspected appearance defects, the QE engineer should set the limit sample and appearance auxiliary standards
V. Electroplating product inspection-packaging inspection
The packaging inspection of electroplated products requires the correct packaging direction, the packaging tray and box are clean and tidy, and there is no damage: the label is filled in completely and correctly, and the number of internal and external labels is consistent.
VI. Electroplating product inspection – salt spray test
After the salt spray test, the surface of unqualified electroplated parts will turn black and rust red. Of course, different types of electroplating will produce different results.
The salt spray test of electroplated products is divided into two categories: one is the natural environment exposure test; the other is the artificial accelerated simulated salt spray environment test. The artificial simulated salt spray environment test uses a test equipment with a certain volume space – the salt spray test chamber, and uses artificial methods in its volume space to create a salt spray environment to assess the salt spray corrosion resistance quality of the product.
Artificial simulated salt spray test includes:
1) Neutral salt spray test (NSS test) is the earliest and most widely used accelerated corrosion test method. It uses a 5% sodium chloride salt solution with a pH value adjusted to a neutral range (6-7) as a spray solution. The test temperature is 35°C, and the salt spray sedimentation rate is required to be between 1 and 2ml/(h· 80cm²).
2) The acetic acid salt spray test (ASS test) is developed on the basis of the neutral salt spray test. It is to add some glacial acetic acid to the 5% sodium chloride solution to reduce the pH value of the solution to about 3, the solution becomes acidic, and the salt spray formed at last also changes from neutral salt spray to acidic. Its corrosion rate is about 3 times faster than the NSS test.
3) The copper salt accelerated acetic acid salt spray test (CASS test) is a fast salt spray corrosion test recently developed abroad. The test temperature is 50℃. A small amount of copper salt-copper chloride is added to the salt solution to strongly induce corrosion. Its corrosion rate is about 8 times that of the NSS test.
The above are the inspection standards and inspection methods for electroplating products, including electroplating product film thickness inspection, adhesion inspection, solderability inspection, appearance inspection, packaging inspection, salt spray test. More electroplating inspection and methods please contact TTS.
Post time: Mar-03-2025