IPC-7095C-2013.pdf - 第170页

ANSI/IPC-T -50 T erms and Deﬁnitions for Interconnecting and Packaging Electronic Circuits Deﬁnition Submission/Approval Sheet The purpose of this form is to keep current with terms routinely used in the industry and the…

A.1 Process Characterization The process characteriza-

tion information is based on void size and follows the rec-

ommendations of the ﬂow diagram shown in Figure A-1.

The combination of void location, void size, and number of

occurrences helps to establish the actions required based on

the standard IPC three class structures. Table A-1 identiﬁes

the recommendations for ball pitches of 1.5, 1.27 and

1.0 mm. Table A-2 identiﬁes the recommendations for ball

pitches of 0.8, 0.65, 0.5 mm. Table A-3 identiﬁes the rec-

ommendations for pitches of 0.5, 0.4 and 0.3 mm using the

via-in-pad technology.

All three tables identify the particular void types and relate

this information to the number of occurrences that there

could be in the three performance classes adopted by IPC.

The evaluation of an increase in the number of voids that

has been set as a target value can be a good aide to deter-

mining a process shift or a required change in some of the

process parameters. A process change should be driven by

an appropriate SPC methodology which should be used

during normal production cycles.

The use of these tables should also be for new product

introduction, product and process qualiﬁcations, equipment

set changes, component qualiﬁcations, response to cus-

tomer feedback and any similar change to the process or

parameters. The sampling plan used should be done at a

printed circuit assembly level, unless the SPC results show

a component related issue i.e., voids in one collapsible

BGA and no voids across the other collapsible BGAs on

the board. In this case, the sampling plan should be

executed at a component level of the suspect component

part rather than examining the assembly process.

Fine Pitch BGAs – The amount of attachment area that

remains after the void is identiﬁed in the ﬁne pitch BGAs

is much less than in the standard pitch BGA. Table A-2 is

intended to show the corrective actions that should be

taken when the X-ray image shows the presence of voiding

in the incoming evaluation of the component or the evalu-

ation after assembly. The ball image is based on the BGA

pitch and, as it gets smaller, so does the land and the resul-

tant attachment area. The recommendations for corrective

action have taken this into account and reduced the void

size to compensate and thus improve the ﬁnal attachment

reliability.

Via-in-Pad Design in Fine Pitch BGAs – As designs get

into ﬁner and ﬁner pitch, the need to obtain sufficient rout-

ing space encourages the use of microvias and via-in-pad

design. The conditions become more critical especially in

the use of designs that require lead-free assembly. Figure

A-2 shows an example as to how the cracks in the solder

joint propagates out from the void that has been created by

the absence on material in the land. This condition can be

overcome if the via is ﬁlled and over-plated so that air

entrapment does not promote this condition. Via-in-pad

designs require a further restriction of void allowance as

shown in Table A-3.

Process control criteria for the number and size of voids

discourage a general presence of voids, which indicates an

out of control process and calls for the need to use the nec-

essary tools for process and material improvement. Void

size is also important as shown in Tables A-1 to A-3 and

Figure A-3. The criteria deﬁne the characteristics for void

acceptability based on size and pitch.

For collapsible solder balls, when attached to the land pat-

tern, the ball takes an elliptical sphere form rather than a

uniform round sphere shape. Therefore, the solder joint

diameter at the ball’s center is typically greater than the

diameter at the ball-to-land interface. The criteria applied

to varying ball sizes and land sizes will result in different

void sizes.

IPC-7095c-a-2

Figure A-2 Voids in BGAs with Crack Started at Corner Lead

crack

BGA ball at 1

corner pin

BGA ball adjacent to 1

corner pin

no crack

IPC-7095c-a-3

Figure A-3 Void Diameter Related to Land Size

Solder Land Area

12% Void Area

January 2013 IPC-7095C

155

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

--`,,```,,,,````-`-`,,`,,`,`,,`---

ANSI/IPC-T-50 Terms and Deﬁnitions for

Interconnecting and Packaging Electronic Circuits

Deﬁnition Submission/Approval Sheet

The purpose of this form is to keep

current with terms routinely used in

the industry and their deﬁnitions.

Individuals or companies are

invited to comment. Please

complete this form and return to:

IPC

3000 Lakeside Drive, Suite 309S

Bannockburn, IL 60015-1249

Fax: 847 615.7105

SUBMITTOR INFORMATION:

Name:

Company:

City:

State/Zip:

Telephone:

Date:

❑ This is a NEW term and deﬁnition being submitted.

❑ This is an ADDITION to an existing term and deﬁnition(s).

❑ This is a CHANGE to an existing deﬁnition.

Term Deﬁnition

If space not adequate, use reverse side or attach additional sheet(s).

Artwork: ❑ Not Applicable ❑ Required ❑ To be supplied

❑ Included: Electronic File Name:

Document(s) to which this term applies:

Committees affected by this term:

Office Use

IPC Office Committee 2-30

Date Received:

Comments Collated:

Returned for Action:

Revision Inclusion:

Date of Initial Review:

Comment Resolution:

Committee Action: ❑ Accepted ❑ Rejected

❑ Accept Modify

IEC Classiﬁcation

Classiﬁcation Code • Serial Number

Terms and Deﬁnition Committee Final Approval Authorization:

Committee 2-30 has approved the above term for release in the next revision.

Name:

Committee: Date:

IPC 2-30

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

--`,,```,,,,````-`-`,,`,,`,`,,`---

Put IPC MEMBERSHIP to WORK for your COMPANY

Keep on top of industry developments …

and how they will affect your company

• Enjoy 24/7 privileges to FREE members-only online resources, including a

searchable archive of original articles and presentations on the latest technical

issues and industry/market trends.

• Receive FREE exclusive statistical reports available for the EMS, PCB, laminate,

process consumables, solder and assembly equipment industries.

• IPC events, including IPC APEX EXPO

, technical conferences, workshops,

training and certication programs and executive management summits provide

unparalleled educational and networking opportunities.

• Stay abreast of global environmental directives, legislation and regulations, and

how these specically impact each segment of our industry’s supply chain.

Save enough money to easily pay for your

membership

• Get discounts of up to 50 percent on IPC standards, publications and training

materials.

• Save money on online subscription licenses of IPC standards through the world’s

largest standards reseller — IHS.

• Enjoy dramatic discounts on registration fees for meetings, technical

conferences, workshops and tutorials.

• B enet from preferred pricing on exhibit space at IPC trade shows and events.

“

Graphic PLC has enjoyed the privilege of being

an IPC member for more than 30 years and the

technical beneﬁts derived to focus us as a world

player in the manufacture of PCBs have superceded

the cost of membership many times.”

Rex Rozario, OBE

Chairman

Graphic Plc.,UK

“ Being a part of the fast-changing global electronics

marketplace requires constant intelligence about

market trends, standards and solutions to the

challenges throughout the supply chain. IPC is an

invaluable partner in providing that intelligence

through conferences, white papers and technical

standards.”

Andy Hyatt

Executive Vice President

Business Development

Creation Technologies

A trusted leader for more

than 50 years, IPC is the

premier source for industry

standards, training, market

research and public policy

advocacy — supporting the

needs of the estimated $1.7

trillion global electronics

industry.

For less than $3.00 a

day, IPC members enjoy

unlimited access to the

tools, information and

forums needed to thrive in

an ever-changing electronic

interconnect industry.

“ I have a responsibility to

my customers and my

shareholders. Between the

savings on standards, training

materials, APEX and industry

data, IPC membership

provides immediate 100%

return on investment for us. It

would be irresponsible not to

be a member.”

Joseph F. O’Neil

President

Hunter Technology Corp

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

--`,,```,,,,````-`-`,,`,,`,`,,`---