Thomas Keppel Cloetingh, 67, of Phoenixville and Amelia Island, Fla., an entrepreneur and philanthropist, died Thursday, Nov. 19, of complications from Lewy body dementia at his Chester County home.

Mr. Cloetingh was diagnosed with the brain disease in 2017. Earlier this month, he was placed in hospice care.

Born in Grand Rapids, Mich., he was raised in the Philadelphia suburbs. He graduated from Lower Merion High School in 1971 and earned a bachelor’s degree from George Washington University in 1975 and an MBA from Drexel University in 1977.

Mr. Cloetingh was founder and CEO of the Wayne-based Signal Holdings LLC, a provider of protection programs and repair services for cell phones. His brother Stephen was an executive vice president.

Between 1984 and 2008, when the firm was sold to business partner Assurant Inc., the Cloetingh brothers built Signal Holdings into a business with annual revenue of about $330 million and 700 employees in four Pennsylvania locations. After the $250 million sale, the Cloetinghs became part of the merged company’s senior management before moving on, the Philadelphia Business Journal wrote in 2008.

“Tom used his brilliance, judgment, integrity, persistence, steady work ethic, and sheer good luck to found and grow the business, and at the same time, invent an industry, before selling to Assurant,” his family said in a statement.

The business originated as a start-up focused on the nascent mobile phone insurance market. At that time in the 1980s, the phone industry was dominated by large landline carriers and consumers who used landlines.

Signal Holdings adjusted as mobile phones transitioned from brick-size phones to smaller flip phones and finally to smartphones. The company sold a partial stake in the business to Stone Point Capital in 2002, before the deal with Assurant. Mr. Cloetingh was adamant that layoffs be avoided, and most employees were kept on by Assurant.

Mr. Cloetingh retired 18 months after the 2008 sale.

Beginning in retirement, Mr. Cloetingh was a philanthropist in the fields of education, health, and the environment.

He supported Philabundance, Penn Medicine Memory Center’s Lewy body research, refurbishment of the Colonial Theater in Phoenixville, and Good Works, a Coatesville nonprofit that helps low-income homeowners repair their houses.

“He was dedicated to creating healthy, inclusive, and just communities where individuals have the resources to overcome challenges, achieve their goals, and live meaningful lives,” the family said.

Mr. Cloetingh met Joan Edwards and married her in 1976. They had three children whom they raised in Phoenixville. He was passionate about creating a family with strong values. He had a “work hard, play hard” approach to life.

While juggling his business responsibilities, he made it a point to be present for his family. He cheered at his children’s athletic matches, prioritized getting home for weekday dinners, and loved hosting large family gatherings.

“He especially loved Thanksgiving. He loved cooking the turkey,” said his brother Stephen.

Although genial and soft-spoken, Mr. Cloetingh had a contagious belly laugh, his family said.

He enjoyed golfing, skiing, and following the Philadelphia sports teams, and was a longtime holder of season tickets to the Eagles and Flyers. “It’s a good way to hold the family together,” he liked to say.

Besides his wife and brother Stephen, he is survived by children Jeffrey Scott Cloetingh, Julie Cloetingh Cady, and Gregory Thomas Cloetingh; six grandchildren; two other brothers; and two sisters.

Services were Nov. 24. Interment will be private.