PCB Quality Control & Inspection

Quality standards are essential elements of the printed circuit board (PCB) manufacturing. In industrial manufacturing, PCBs are often produced in high volumes. Therefore, any default in the production process would affect the effective functioning of the hundreds or thousands of final products. Besides, when customers make orders, they expect to receive quality and reliable PCB products. To ensure that our customers are satisfied with our products and services’ quality, we have a Quality Management System that is compatible with the IPC standards.

At MKTPCB, we acknowledge the fact that quality is not something inspected into customer orders. We build it into our products from the moment customers make their orders. Our support team is dedicated to guiding our clients towards optimum manufacturability. We also conduct rigorous PCB visualization checks to ensure we provide the best quality products and services.

MKTPCB Quality Standards

We check and ensure our PCB products are up to IPC-A-600 Class 2 standards. This is the PCB standard recommended by IPC and is often specified by our clients. IPC stands for the Institute for Printed Circuit Boards. Basically, it is an international trade association representing all aspects of the PCB industry, such as design, manufacturing, fabrication, and assembly.

The IPC-A-600 standard refers to the ideal, tolerable, and non-compliant terms that are either externally or internally visible on PCBs. It classifies circuit boards into three product classes. Class 2 comprises products where continuous performance and prolonged life are necessary and where continuous service is desired but not a must. Class 3 products, where uninterrupted service is essential, are used in the healthcare, aerospace, and defense sectors.

Manufacturers, especially those serving the US market, must also indicate the UL markings in their products. For this reason, we further inspect our PCB products to UL796. The Underwriters’ Laboratory (UL) is an independent global safety science body zealous to support safe living and working environments. In particular, the body helps to protect workers, products, and workplaces in fundamental ways, improving businesses and workers’ wellbeing. For printed circuit boards, the most crucial standard emphasized by UL making is flammability. All MKTPCB FR4 materials satisfy UL-94 VO plastic flammability tests.

Our Inspection Steps During Production

Step 1: Front-end Manufacturing

Front-end manufacturing is the first production inspection step that ensures that the data we use to design your board is correct.

Step 2: Fabrication Tests

MKTPCB conducts three fabrication tests, namely: visual, non-destructive measurements, and destructive tests. We leverage destructive tests to check our fabrication processes. We implement them on actual boards or on the test coupons, which we include in our production panels. With more than ten years of PCB manufacturing experience, we have developed several test coupons for our production panels to offer simple, non-destructive tests for complicated considerations.

Step 3: Passport

The outcomes of the quality standard checks are briefed for every job in its Passport, which bears data on the materials used, measurements, and approved tests.

Step 4: Traceability

If you require more information on a job, we provide full traceability of the entire production process. We use a data-matrix to check the base materials against customer order details. We then enter the material information (type, manufacturer, laminate, and copper foil thickness) into the project account.

Step 5: Printing and etching internal layers

This step comprises three checks. We carry out the first check after printing and stripping to strip away the unwanted etch resist. Then, we conduct the second inspection after etching to ensure that all the undesired copper has been etched away. Lastly, we conduct the third check to stripe all the etch resist from the PCB at the end of the process.

Every production panel contains its test coupon, confirming that the PCB has been appropriately etched and that the track measurements are right. We then enter the etch resist and the values for track measurements, isolation distances, and annular ring into the Passport document.

Step 6: Inspecting the Internal Layer Copper Patterns

We apply the Automatic Optical Inspection machine to examine the internal layer copper patterns and confirm whether they align with the design information. The equipment ensures that each track width and isolation distance conforms to the design values. Additionally, it also ensures there are no short or open circuits that may make the final product flop.

Step 7: Multilayer Bonding

We use a data matrix to check the materials against the order information. Additionally, we take the thickness-after bonding measurements of every production panel and enter them into the Passport.

Step 8: Drilling

Our drilling equipment automatically checks drill diameters to ensure the holes have the correct measurements. Besides, we use a special test coupon on multilayer PCBs to check the position of the holes relative to the internal layers.

We apply a carbon layer to the holes to make them conducive for electroplating.

We carry out visual checks after printing and stripping to strip away the undesired plating resist. In this step, we also enter the resist type into the Passport.

Step 9: Copper and Tin Plating

This is a non-destructive sample check. We take the copper thickness measurements at five or more points on every panel of a light bar.

Step 10: Outer Layer Etching

We carry out visual checks to etch away all the unwanted copper. Additionally, we do sample checks in this step. Every production panel contains its test coupon that shows that the PCB has been appropriately etched and that the track measurements are correct. We enter the etch resist we used, track values, isolation spaces, and annular ring into the Passport document.

Our Quality Inspection Process for Sourced Components

At MKTPCB, we have laid out a 5-step quality inspection procedure to ensure products are 100% functional:

First Article Inspection (FAI)

MKTPCB acknowledges FAI as the initial step of quality inspection prior to the mass production of circuit boards. We put up this step to avoid producing large quantities of defective products due to processing and operational issues.

We inspect every resistor, capacitance, and inductance using an LCR meter. Besides, we use QC with BOM and Assembly drawing to verify chips.

Automatic Optical Inspection (AOI)

The AOI process verifies the placement of electronic components and solder joints after SMT. The primary objective is to get the highest quality control and detect and remove defects in the assembling process’s earlier stages.

X-Ray Inspection

In this step, we use short wavelengths of 0.0006-80nm to penetrate various PCB materials. Designs with BGA and QFN packages have solder joints that are not easily visible by human eyes. We employ X-ray machines to inspect such packages in the final printed circuit board assembly.

Final Quality Assurance (FQA)

After carrying out FAI, AOI, and X-Ray inspections, our quality engineers conduct the last visual quality inspection process for all products. This process ensures that products have gone through all the assembling processes and are of good quality.

Function Test

Finally, we also conduct functional tests on all automated test equipment to simulate different loads, typically normal, peak, and abnormal loads. This is a complicated process that involves various tool-based and programming tests. Additionally, this step requires customer technical support.

Guided by IPC Standards

To help PCB designers, manufacturers, and the end-users have a common interest, the Association Connecting Electronics Industries (IPC) was instituted. Established in 1957, IPC standards are meant to standardize the PCB manufacturing and assembly requirements.

Through the application of IPC standards, MKTPCB designs reliable boards that function even in adverse conditions, condense our marketing time, and instill confidence in our final products when applied in various industries.

But does the use of quality standards matter? Absolutely. Let us assume you created boards without recognized standards:

You would not always obtain a board that satisfies your requirements.
You would experience the danger of multiple interpretations of the same concept.
You would be unable to achieve the right quality level.
You would be unable to compare ‘like for like products or manufacturers.
Your projected marketing time would be a gamble instead of relying on good factory selection and design.

Now that we are reading from the same page regarding the importance of standards, are the IPC standards practical? Yes! Through IPC standards, designers, manufacturers, and end-users enjoy numerous benefits like high-quality products and services, improved competitiveness, minimized rework and filed failures, reduced redundant scrap, high throughput, and profitability.

Our PCB Specifications

Our rich experience in PCB manufacturing and assembly has taught us that unit cost is not the first and final concern. It would be best if you also prioritized the durability and reliability of your end products. At MKTPCB, we endeavor to add value to our PCB products while keeping the cost factor at a minimum. Although IPC standards act as a strong foundation, our stipulations prescribe requirements that sometimes go above and beyond the IPC standards. Still, we manage to do this in a way that introduces more protection layers to our products.

One of the requirements we stress is that each PCB hole should be plated per IPC 6012 class 3 requirements. We try to apply this principle to all products, regardless of whether they are healthcare products or not. When a PCB undergoes the thermal processes, it tends to expand in the z-axis- a wrongly plated hole will most likely act as a weak point, leading to PCB failure.

We also emphasize the open circuit repair requirement. We have established that a repaired circuit always affects the final product, be it on the impedance needed, or in some instances, on the general reliability of the fixed trace. If the repair is done on the inner layers, it may not be visible, but it will still hinder the final product.

Besides, we have other standards such as a minimum solder mask thickness and cleanliness level above what IPC states. We have a definite profile, holes, and different mechanical feature tolerances, which back the end product’s durability and reliability.

Certifications

A certificate is to prove that all customer specification requirements are maintained in PCB manufacturing, including the following items.

All PCBs shipped comply with purchasing specifications and drawings.
Where there is no specification in the drawings and materials supplied, we use the IPC manual.
The laminate and prepreg we use in fabrication comply with IPC-4101.
Our final products are 100% electrically tested and approved.
Final PCBs meet all the requirements of UL 796 and flammability rating 94V0.
The non-operational printed circuit board and packing material should be discarded according to local laws.

MKTPCB is fully ISO9001:2000, ISO14001, Ts16949, UL and RHoS certified. You can trust with all your PCB needs if you need quality and cost-effective service.

What is ISO9001:2000 Certification?

ISO9001:2000 is a business-level certification based on standards developed and issued by the International Organization for Standardization (ISO) labeled “Quality Management Systems Requirements.” This standard is an improved version of the ISO9001:1994 standard to adhere to more logical formats, be more environmentally friendly, and emphasize customer satisfaction by getting in touch with customers throughout the production process and checking customer satisfaction.

ISO9001:2000 can be classified as a non-industry-specific certification that offers guidelines and requirements for executing and sustaining a quality management system. It contains clauses related to topics like documentation and personal dedication necessary to maintain a certified quality management system.

Only authorized bodies give certifications. The certifying body is responsible for carrying out yearly audits where sections of a company are assessed for continued accreditation. Besides, a certification audit is done every three years to review the whole company.

Under the requirements of ISO9001:2000, MKTPCB is devoted to offer products that exceed and enhance customer satisfaction rates consistently.

What is UL Certification?

UL is an abbreviation for Underwriter Laboratories, a third-party certification body that has been in operation for more than a century. UL was established in 1894 in Chicago. The body certifies products with the mission of making the world a safer place for both employees and end-users. Apart from testing, they lay industry standards for use when introducing new products to the market. It is estimated that over 14 billion products with the UL seal enter the global market annually.

UL standards require manufacturers to thoroughly test their PCBs and power supply products by following the proper industry procedures to reduce product risks. UL categorization services vary from specific threats like performance within specified conditions, and regulatory codes, to other general desirable standards. This enables consumers to be aware of the various product standards.

Since we became UL certified, MKTPCB has been championing quality testing services. Currently, we conduct various quality tests, like First Article Inspection (FAI), Automated Optical Inspection (AOI), X-ray Inspection, Final Quality Assurance (FQA), and Function Tests on our components and products. The aim is to offer high-quality PCB products and services to our global pool of clients.

What is RoHS?

RoHS stands for Restrictions of Hazardous Substances and refers to a set of preventive laws of using six hazardous materials in PCB manufacturing. These materials include Lead (Pb), Mercury (Hg), Cadmium (Cd), Hexavalent Chromium (Cr VI), Polybrominated Biphenyls (PBB), and Polybrominated Diphenyl Ethers (PBDE).

Initially, RoHS standards were only applicable in Europe, but they are now applied globally. These standards cover the entire electronic industry and some electrical products. They define the maximum concentration of hazardous substances in electronic products.

MKTPCB offers custom boards and assemblies with surface finishes in line with the RoHS requirements, like lead-free HASL, ImAG, ENIG, and others. In addition, we offer RoHS compatible laminate material that withstands extreme temperatures in assembly processes.

Outgoing Report

Cover and Document list

Certification Of Compliance
Final Product Inspection Report
Hole Size and Outline Dimension
Micro-section Report
Solderability and Thermal Stress Report
E-Test Report
RoHS Compliance Statement
Ionic Contamination Report
Impedance Test Report

Certificate of Compliance

Certification Items

This certificate is to serve as proof that all requirements of customer’s specification are maintained in fabrication of this including the followings.

1. All PCBs shipped comply with purchasing specifications and/or drawings.

2. Where no spec in the drawings and/or materials supplied, IPC is available.

3. Laminate and prepreg used in fabrication are in compliance with IPC-4101.

4. All finish boards have been 100% electrically tested and passed.

5. Finish boards meet all requirements of UL 796 and flammability rating 94V0.

6. Non-operational printed circuit board and packing material should be discarded according to local laws.

All information listed on this document is hereby certified in writing to be true.

Final Product Inspection Report

(B) Material
1	Raw Material		FR4,Tg170 EMC EM827	YES	√
2	Core Thickness		0.13±0.018mm	YES	√
3	Copper Thickness (OZ)		(1/3)/1/1/1/1/1/1/(1/3)	YES	√
(C) Marking & Circuitry
1	Min Line Width		0.102-0.152mm	0.13mm	√
2	Min Spacing		0.162-0.244mm	0.20mm	√
3	Front & Back registration		+/- 0.076mm	YES	√
(D) Surface treatment thickness
1	Process		Immersion Gold	OK	√
2	HAL		/	/	/
3	lead-Free HAL		/	/	/
4	Immersion Gold	Ni	3-6um	4.326um	√
4	Immersion Gold	Au	0.050um(min)	0.059um	√
5	Immersion Silver		/	/	/
6	Immersion Tin		/	/	/
7	Gold Finger	Ni	/	/	/
7	Gold Finger	Au	/	/	/
8	OSP		/	/	/
(E) Soldermask & Component Marking
1	S/M Material & Color		SR-500 G40 & Green	YES	√
1	Applied on		C/S S/S	YES	√
2	S/M Tape Test/Solvent Test		No peeloff	YES	√
3	S/M Registration		No Misregistration	YES	√
4	C/M Material (Color)		White	YES	√
4	Applied on		C/S S/S	YES	√
5	C/M Tape Test / Solvent Test		No peeloff	YES	√
6	C/M Registration		No Misregistration	YES	√
(F) Profile
1	Overall Thickness		1.6±0.16mm	1.56-1.64mm	√
2	Bow & Twist (max)		0. 75%	0.22%	√
(G) Functional Test
1	Electrical Test		No Open/Short	YES	√

(H) Hole Size & Outline Dimension Report

Finished Hole Size (Unit: inch)

Code	Qty	Requirement	Actual	Acc/ Rej	Remarks
1	1700	0.008+/-0.003	0.007	ACC
2	2833	0.010+/-0.003	0.010	ACC
3	2	0.032+/-0.003	0.031	ACC
4	30	0.034+/-0.003	0.034	ACC
5	24	0.035+/-0.003	0.035	ACC
6	10	0.040+/-0.003	0.041	ACC
7	10	0.045+/-0.003	0.046	ACC
8	2	0.052+/-0.003	0.052	ACC
9	2	0.071+/-0.003	0.072	ACC
10	14	0.138+/-0.003	0.138	ACC
11	4	0.080+/-0.002	0.080	ACC
12	2	0.128+/-0.002	0.129	ACC

Code	Qty	Requirement	Actual	Acc/ Rej	Remarks
13	14	0.060+/-0.003	0.062	ACC
13	14	0.040+/-0.003	0.039	ACC
14	16	0.060+/-0.003	0.060	ACC
14	16	0.040+/-0.003	0.040	ACC
15	2	0.075+/-0.004	0.075	ACC
15	2	0.025+/-0.003	0.025	ACC
16	2	0.175+/-0.004	0.174	ACC
16	2	0.025+/-0.003	0.025	ACC
17	1	0.250+/-0.004	0.249	ACC
17	1	0.025+/-0.003	0.025	ACC

Dimension Measurement (Unit: mm)

No.	Requirement	Tolerance	Actual	Acc/ Rej
1	5.00	+/-0.13	5.00	ACC
2	110.00	+/-0.13	109.99	ACC
3	100.00	+/-0.13	100.02	ACC
4	1.524	+/-0.13	1.56	ACC
5	52.817	+/-0.13	52.80	ACC
6	154.00	+/-0.13	154.01	ACC

V- cut Measure (Unit:mm)

Items

Requirement

Actual

Acc/Rej

Angle

30±5°

30°

ACC

Thickness

0.4±0.1

0.39

ACC

Beveling Measure (Unit:mm)

Items

Requirement

Actual

Acc/Rej

Angle

Deepness

Micro-section Report

Hole Wall Microsection Data (Unit: μm)

Request	Minimum:18.0						Average: ≥20.0
No.	A	B	C	D	E	F	minimum	Average
1	34.0	30.0	32.0	32.0	31.0	32.0	30.0	32.0
2	32.0	31.0	33.0	34.0	30.0	33.0	30.0	32.0
Result	ACC

Blind Hole Wall Copper Data (Unit: μm)

Request	Minimum: /						Average:/
No.	A	B	C	D	E	F	minimum	Average:
1							0.0	#DIV/0!
2							0.0	#DIV/0!
Result	/

Buried Hole Wall Copper Data (Unit: μm)

Request	Minimum: /						Average:/
No.	A	B	C	D	E	F	minimum	Average:
1							0.0	#DIV/0!
2							0.0	#DIV/0!
Result	/

Copper Thickness Data (Unit: μm)

Layer	Base copper	Finish Copper Requirement (From Customer or IPC)		Actual	Result
Top Side	1/3OZ	≥38. 4		48.0	ACC
L2	1OZ	min:	24.9	29.0	ACC
L3	1OZ	min:	24.9	31.0	ACC
L4	1OZ	min:	24.9	30.0	ACC
L5	1OZ	min:	24.9	29.0	ACC
L6	1OZ	min:	24.9	30.0	ACC
L7	1OZ	min:	24.9	31.0	ACC
Bottom Side	1/3OZ	≥38. 4		46.0	ACC

Soldermask Thickness Data (Unit: μm)

Speciment Location	Request	Actual	Result
Circuit Surface	10(min.)	24.0	ACC
Circuit Corner	5(min.)	20.0	ACC

Dielectric Measurement Record (Unit: μm)

Layer	Request	Actual	Result
L1-L2	94+/-18	90.0	ACC
L2-L3	130+/-25	125.0	ACC
L3-L4	341+/-50	335.0	ACC
L4-L5	130+/-25	125.0	ACC
L5-L6	340+/-50	350.0	ACC
L6-L7	130+/-25	124.0	ACC
L7-L8	93+/-18	100.0	ACC

Solderability & Thermal Stress Test Report

Test Method: Follow IPC-TM-650 Standard

Item 1: Solderability Test

Condition	Temperature	Time	Result		Accept/Reject	Remark
	255℃±5℃	4S±0.5S	Blow-hole	Non-Wetting
	235℃±5℃		NO	NO	ACC

Item 2: Thermal Stress Test

Condition	Temperature	Time	Result						Acc/Rej
	288℃	10S,3Times	Discolor	Delamination	Measling	S/M peel off	Blister	Crack	Acc/Rej
	288℃	10S,3Times	NO	NO	NO	NO	NO	NO	ACC

E-Test Report

Test Method: Fixture Flying Probe
Test condition
A	Testing coverage rate	100%
B	Voltage	≥300V
C	Continuity Test	≤30Ω
D	Insulation Test	≥30MΩ

RoHS Compliance Statement

Statement items
No.	Substance	Control Limit
1	Lead (Pb)	Under 1000ppm
2	Mercury (Hg)	Under 1000ppm
3	Cadmium (Cd)	Under 100ppm
4	Hexavalent Chromium	Under 1000ppm
5	Polybrominated biphenyls (PBB)	Under 1000ppm
6	Polybrominated diphenyl ethers (PBDE)	Under 1000ppm
7	Bis(2-ethylhexyl) phthalate (DEHP)	Under 1000ppm
8	Butyl benzyl phthalate (BBP)	Under 1000ppm
9	Dibutyl phthalate (DBP)	Under 1000ppm
10	Diisobutyl phthalate (DIBP)	Under 1000ppm

Impedance Test Report

Test Result
NO.	Request (Ω)	Layer	Referance layer	Line width (mm)	Line Space (mm)	Actual test data			Accept/Reject
NO.	Request (Ω)	Layer	Referance layer	Line width (mm)	Line Space (mm)	Max(Ω)	Min(Ω)	Average(Ω)	Accept/Reject
1	50+/-5	L1	L2	0.152	/	50.82	48.77	49.80	ACC
2	50+/-5	L1	L3	0.460	/	52.02	47.50	49.76	ACC
3	100+/-10	L1	L2	0.130	0.198	102.37	97.94	100.16	ACC
4	90+/-9	L1	L2	0.150	0.178	90.82	87.98	89.40	ACC
5	50+/-5	L1	L2	0.384	0.203	51.15	48.42	49.79	ACC
6	50+/-5	L3	L4/L2	0.127	/	50.08	48.63	49.36	ACC
7	100+/-10	L3	L4/L2	0.117	0.211	100.54	99.51	100.03	ACC
8	50+/-5	L6	L5/L7	0.127	/	50.07	49.95	50.01	ACC
9	100+/-10	L6	L5/L7	0.117	0.211	100.17	98.37	99.27	ACC
10	50+/-5	L8	L7	0.152	/	51.04	47.68	49.36	ACC
11	50+/-5	L8	L6	0.460	/	51.09	49.50	50.30	ACC
12	100+/-10	L8	L7	0.130	0.198	100.82	98.73	99.78	ACC